Investigation and treatment after non-ST segment elevation acute coronary syndrome for patients presenting to rural or urban hospitals in Aotearoa New Zealand: ANZACS-QI 75
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In Aotearoa New Zealand, patients with non ST-segment elevation acute coronary syndrome (NSTEACS) may present to one of three main groups of hospitals: urban hospitals i) with (interventional) or ii) without (non-interventional) routine access to percutaneous intervention (PCI), or iii) rural hospitals.[[1,2]] Hospitals without routine access to PCI typically have smaller catchments that include a higher proportion of Māori.[[3]] Rural hospitals usually have fewer resources and are at a distance (40 minutes to 4 hours by road) to urban hospitals.[[4]]
Patients who present to hospitals without access to PCI will receive initial treatment at that facility. Stable patients in urban hospitals or larger rural hospitals may be admitted to that facility while awaiting transfer for invasive coronary angiography (angiography hereafter) and further treatment. Unstable patients or those who present to rural hospitals that have fewer resources may require early transfer to a larger hospital. Patients may undergo several hospital transfers to receive definitive care.[[5]]
For patients with NSTEACS, guidelines recommend that angiography is performed within 3 days for all but very low-risk patients (Aotearoa New Zealand target is 70%), that there should be an assessment of left ventricular function (Aotearoa New Zealand target is 85%) and secondary preventative medications are prescribed (Aotearoa New Zealand target is 85%).[[6–8]]
Recent data from Aotearoa New Zealand show that patients with ST elevation myocardial infarction (STEMI) and NSTEACS that present to urban non-interventional or rural hospitals were less likely to receive angiography, but there are no differences in mortality (up to 1 year) and few differences in readmissions to hospitals with adverse cardiac events, heart failure or major bleeding.[[1,2]] However, regardless of the type of hospital at presentation, Māori have higher mortality following STEMI and NSTEACS compared to non-Māori, non-Pacific peoples and have reduced access to invasive cardiac investigations.[[9]] These inequities are more pronounced for Māori that live in rural areas.[[9,10]] There are few data on the investigations and treatments provided to patients that present to Aotearoa New Zealand rural hospitals with NSTEACS.
The aim of this study was therefore to determine if there were differences in the inpatient investigations and treatments that patients received during an admission with NSTEACS associated with the category of hospital (rural, urban non-interventional or urban interventional) that the patient presented to, and to explore any interactions with ethnicity.
Methods
All first admissions to Aotearoa New Zealand public hospitals for patients aged 20 or older with NSTEACS entered in the All New Zealand Acute Coronary Syndrome Quality Improvement (ANZACS-QI) programme between 1 January 2014 and 31 December 2019 were included in the study.
The ANZACS-QI ACS-CathPCI registry was used, which captures in-depth data on the subset of patients that have acute coronary syndrome (ACS) and receive a coronary angiogram in Aotearoa New Zealand public hospitals (approximately 60% of patients with NSTEACS).[[1,2,11,12]]
Hospitals were identified using the facility code assigned by the New Zealand Ministry of Health and divided into three urban–rural hospital categories (Table 1):[[1,2]]
1. Urban hospitals with routine access to PCI (urban interventional)
2. Urban hospitals without routine access to PCI (urban non-interventional), or
3. Rural hospitals
Patients were assigned to the first hospital of presentation. To account for the movement of patients between hospitals, admission events were bundled together.[[12]]
View Tables 1–4, Figures 1–3.
Clinical performance measures
Clinical performance measures that were considered included: invasive coronary angiography performed within 3 days of first presentation; an assessment of the left ventricular ejection fraction (LVEF); and whether the following medications were prescribed at discharge—aspirin, dual antiplatelet therapy (DAPT), statin, angiotensin-converting enzyme inhibitor or angiotensin receptor blocker (ACEi/ARB) and beta-blockers. These were selected as key indicators of quality care and are consistent with Aotearoa New Zealand ACS targets, as well as Australasian and international guidelines and existing literature.[[6–8]]
Data collected
Age, sex, prioritised ethnicity categorised as Māori, Pacific and non-Māori, non-Pacific peoples (using the Ministry of Health’s protocols),[[13]] body mass index (BMI), smoking status, history of diabetes, congestive heart failure (CHF), prior cardiovascular disease, renal dialysis, admission heart rate (HR) and systolic blood pressure (SBP), low density lipoprotein cholesterol concentration (LDL), initial Killip group,[[14]] cardiac arrest on arrival, estimated glomerular filtration rate (eGFR), Grace score[[15]] and anticoagulant use were collected.
Clinical information included: the time from arrival at the hospital of presentation to angiography (in days); assessment of the LVEF, either by echocardiogram or left ventricular angiogram; findings from angiogram and LVEF assessment; whether PCI was performed; and if there was a referral for (inpatient or outpatient) coronary artery bypass grafting.
The prescription of, or documented contra-indication, to aspirin, another antiplatelet agent, statin, angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB) or beta-blockers were recorded. Patients were considered to have been prescribed dual antiplatelet therapy if they had both aspirin and a second antiplatelet agent prescribed at discharge.
Statistical analysis
Data were summarised using mean and standard deviation (SD) for continuous data and frequency and percentage for categorical data, overall and by hospital category.
Logistic regression, separately for each performance measure, was used to estimate the odds ratios (OR) with 95% confidence intervals (95% CI) comparing urban non-interventional and rural hospitals with urban interventional hospitals (reference group). A binary outcome was created for the prescription of a medication where “prescribed” or “contra-indication” were re-categorised as “true”.
For all models, the following potential confounders of hospital category were included: sex, ethnicity, age, type of NSTEACS, current smoker, prior cardiovascular event, history of diabetes, BMI, HR, SBP, Killip group, LDL, eGFR, history of CHF, health region (Northern, Te Manawa Taki, Central, Southern) and anticoagulant use. LVEF assessment and the findings from this assessment were both considered additional confounders in the models for angiography that occurred within 3 days and prescription of secondary preventative medications. Angiography within 3 days was considered a confounder in the models for LVEF assessment and the prescription of secondary prevention medications.
All model assumptions were checked. Complex non-linear associations were dealt with by categorisation as follows: age (20–44 years, 45–59 years, 60–69 years, 70–89 years and 90+ years); BMI (<18, 18.5–24.9, 25–29.9, 30–34.9 and 35+), heart rate (<50, 50–99, 100–149 and >150 beats per minute); SBP ( <100, 100–149, 150–200 and 201+ mmHg) and LDL (0–1.9, 2–3.9, 4–5.9 and 6+ mmol/L).
Backwards elimination was used to identify and remove non-significant confounders; however, important confounders (age, ethnicity) were retained regardless of significance. Likelihood ratio tests were used to assess the significance of each variable in the model. Only a priori interactions (age and ethnicity) were investigated.
Large amounts (>10%) of missing data within a single variable were categorised and coded as a separate category and included in the regression models. A sensitivity analysis was performed comparing this method with multiple imputation (Appendix 4).
All analyses were performed in R (version 4.1.1) using R-Studio (22.02.3 Boston, MA).[[16]]
Ethics
The ANZACS-QI study is part of a programme of research originally approved by the Northern Region Ethics Committee in 2003 (AKY/03/12/314), with subsequent approval by the National Multi Region Ethics Committee in 2007 (MEC07/19/EXP) and with annual re-approval since as part of a vascular research programme (2022 EXP 13442). Individual patient consent was not required as all data are de-identified.[[11]]
Results
There were 26,779 patients with NSTEACS between 2014 and 2019. Patient characteristics are presented in Table 2. Most patients (66.2%) presented to urban interventional hospitals, with a quarter of patients presenting to urban non-interventional (25.6%) and 8.2% to rural hospitals. A lower percentage of patients that presented to urban interventional hospitals were Māori, compared to urban non-interventional and rural hospitals (8.1%, 17.0% and 13.0% respectively); however, the reverse occurred for Pacific peoples (7.1%, 1.4% and 1.7%). Compared with interventional hospitals, patients that presented to non-interventional and rural hospitals were also more likely to be older (mean age: 65.6 years, 66.4 years and 67 years respectively) and female (30.4%, 34.8% and 33%).
Findings (including ORs) for the process measures angiography within 3 days and assessment of LVEF are shown in Table 3 and Figure 1. There was a significant (p<0.001) interaction between ethnicity and category of hospital for both these two outcome measures.
Invasive coronary angiography within 3 days
Overall, 72.7% of patients received angiography within 3 days; of this, a higher percentage were patients that presented to urban interventional hospitals (78.5%) than rural (60.8%) and urban non-interventional hospitals (63.8%).
For patients presenting to urban interventional hospitals, a lower percentage of Māori (74.3%, OR: 0.78, 95% CI: 0.68 to 0.89) and Pacific peoples (69.3%, OR: 0.75, 95% CI: 0.65 to 0.86) received this investigation compared with non-Māori, non-Pacific peoples (79.8%). For all patients that presented to rural or urban non-interventional hospitals, fewer patients received angiography within 3 days.
Figure 2 shows the time to angiography for each ethnicity and hospital of presentation category.
Assessment of LVEF
Overall, 74.1% of patients received an assessment of LVEF. This percentage was higher for urban interventional (78.5%) compared with rural (66.6%) and urban non-interventional hospitals (65.4%).
A higher percentage of Māori (82.7%, OR: 1.30, 95% CI: 1.12 to 1.51) and Pacific (85.5%, OR: 1.35, 95% CI: 1.14 to 1.62) patients that presented to urban interventional hospitals received an assessment of LVEF compared with non-Māori, non-Pacific peoples (77.5%). However, fewer Māori who presented to urban non-interventional hospitals (68.8%, OR: 0.61, 95% CI: 0.53 to 0.71) and rural hospitals (63.2%, OR: 0.40, 95% CI: 0.31 to 0.52) received this investigation. Similarly, compared to non-Māori, non-Pacific peoples presenting to urban interventional hospitals, fewer non-Māori, non-Pacific peoples who presented to rural hospitals (66.6%, OR: 0.56, 95% CI: 0.50 to 0.62) or urban non-interventional hospitals (64.7%, OR: 0.54, 95% CI: 0.50 to 0.58) received an assessment of the LVEF.
The measured LVEF and the angiography findings were similar across the three categories of hospital and are shown in Appendix 1.
Prescription of secondary prevention medications
Figure 3 and Table 4 present the number, percentage and the unadjusted and adjusted ORs for the prescription of secondary prevention medications at discharge. There were no interactions identified.
Most patients received secondary prevention medications. Nearly all patients had a prescription for aspirin (96.1%), with slightly fewer patients who presented to rural hospitals (95.5%, OR: 0.66, 95% CI: 0.52 to 0.85) or urban non-interventional hospitals (95.1%, OR: 0.89, 95% CI: 0.75 to 1.05) receiving this prescription. A higher percentage of patients that presented to rural hospitals or urban non-interventional hospitals were prescribed beta-blockers (88.3%, OR: 1.34, 95% CI: 1.16 to 1.54 and 86.3%, OR: 1.40, 95% CI: 1.28 to 1.53 respectively) compared with urban interventional hospitals (84.3%).
Adjusting for hospital category of presentation, with the exception of ACEi/ARB (Māori 74.3%, Pacific 78.9%, non-Māori non-Pacific 71.0%), there were no clinically significant differences in the percentage of patients that received a prescription of secondary preventative medication between the three ethnic groups (Appendix 2 and 3).
There were large amounts of missing data (23.5%) for the BMI variable. There were no major differences in the interpretation in any of the outcomes after substituting missing values using multiple imputation (Appendix 4).
Discussion
This national study using the ANZACS-QI registry shows that fewer patients (61% and 63%) who presented to rural hospitals or urban non-interventional hospitals had angiography within 3 days of presentation (and therefore the opportunity for intervention) compared with patients who presented to urban interventional hospitals (78.5%). Only patients presenting to urban interventional hospitals met the Aotearoa New Zealand target of 70%.[[8]] In urban interventional hospitals, Māori and Pacific patients were less likely to receive this investigation within 3 days than non-Māori, non-Pacific patients.
A higher percentage of Māori and Pacific patients that presented to urban interventional hospitals received an assessment of the LVEF compared with non-Māori, non-Pacific patients. However, regardless of ethnicity, patients that presented to rural hospitals or urban non-interventional hospitals were less likely to receive this investigation. The Aotearoa New Zealand target (85%) was only met for Pacific peoples presenting to urban interventional hospitals. Overall, the rates of prescribing for secondary prevention medication at discharge were high.
Invasive coronary angiography
That patients presenting with NSTEACS to rural hospitals or urban non-interventional hospitals waited longer to receive angiography is consistent with Aotearoa New Zealand data in patients diagnosed with STEMI.[[1]] Other Aotearoa New Zealand studies show a similar trend, where patients that presented with NSTEACS in district health boards (DHBs) without PCI capabilities were also less likely to have angiography within 3 days.[[17]] These studies did not differentiate rural from urban hospitals and some DHBs will have included hospitals with and without interventional facilities (e.g., Southern).
Inequities in providing timely angiography for Māori and other Indigenous peoples are well documented.[[9,18]] Our study shows that, regardless of where they present, Māori with NSTEACS wait longer for angiography compared to non-Māori, non-Pacific patients. This disadvantage is worsened for Māori and Pacific peoples who live in urban non-interventional and rural catchments. One potential explanation is the historical lack of angiographic capacity in hospitals that serve large Māori and Pacific populations. We might anticipate this situation could improve with the recent addition of cardiac catheter laboratories to both Whangārei and Middlemore hospitals.[[19]] It is also likely that institutional racism and biases at multiple levels contribute to the inequities for Māori and Pacific peoples seen in our study.[[2,9,20]]
Assessment of LVEF
Access to echocardiography varies throughout Aotearoa New Zealand. Hospitals that do not have cardiothoracic services are less likely to offer this investigation.[[21–23]] Our study shows that patients from urban non-interventional or rural catchments are significantly less likely to have LVEF assessment during their admission, even though all patients were transferred to an interventional centre. This is likely due to a service focus on delivering angiography and maintaining rapid patient throughput in these interventional centres, with patients waiting in rural and urban non-interventional hospitals where access to echocardiography is limited. This finding of fewer patients receiving LVEF assessment in non-interventional hospitals has been previously seen in Australian and Aotearoa New Zealand data.[[24]] The percentage of patients that presented to these non-interventional hospitals in Aotearoa New Zealand and received an LVEF assessment lags behind many other countries and regions (e.g., Israel 72–87.9%, Europe 78–93%, China 81%).[[25,26]]
A higher percentage of Māori and Pacific patients who presented to urban interventional hospitals received an assessment of LVEF compared with non-Māori, non-Pacific peoples; however, this was not apparent for Māori who presented to rural hospitals or urban non-interventional hospitals. This is the opposite situation to coronary angiography. The discrepancy could be explained by the presence of well-developed echocardiographic services but the lack of angiography capacity in hospital catchments with large Māori and Pacific populations. Māori patients are also more likely to present with NSTEACS complicated by cardiac arrest or heart failure. In this situation, echocardiography (but not angiography) is prioritised.[[20]] Where echocardiography is less available, this prioritisation is not possible.
Secondary prevention medication
Regardless of the type of hospital patients presented to, the majority received discharge prescriptions for guideline-directed secondary preventative medications.
While the high overall rate of prescription of these medications is consistent with other Aotearoa New Zealand studies,[[27,28]] our results are in contrast to international data that shows patients from smaller regional and rural places who have NSTEACS were less likely to receive guideline-directed medications.[[24]] The lack of meaningful difference in prescribing at the point of discharge between hospital categories doesn’t explain the small increase in 2-year mortality seen in a previous study,[[2]] although long-term maintenance of these medications for patients who live in rural areas requires further examination.
Patients were more likely to get a prescription for beta-blockers if they presented to rural hospitals or urban non-interventional hospitals. International guidelines acknowledge the role of beta-blockers after NSTEACS in patients with reduced ejection fraction,[[6]] but the role of beta-blockers is uncertain in patients with preserved ejection fraction.[[29]] This uncertainty may be reflected in the prescribing of specialist cardiologists but not of more generalist doctors, who are also less likely to know the patient’s LVEF due to the unavailability of echocardiography. In those that did get echocardiography, there were no differences in the measured LVEF between hospital groups.
Strengths and weaknesses
The strength of this study is the use of the ANZACS-QI Cath-PCI registry. This has a high level of capture of patients that receive angiography.[[12]] A potential limitation is that any investigations (e.g., echocardiography) or treatments (including secondary prevention medications) that patients who didn’t receive angiography (approximately 40% of patients with NSTEACS) may have accessed were not able to be included in the analysis.[[2,17]] Additionally, patients were not risk stratified to determine when angiography should occur according to guidelines (e.g., high-risk patients should have angiography within 24 hours).[[6]] This could be reviewed in future studies. A composite medication outcome wasn’t used for this study and so no comparison could be made with the Aotearoa New Zealand target of 85% for this outcome measure.
This study focusses on which type of hospitals patients present to, rather than the rural–urban category of their usual residence. Future studies using the Geographic Classification for Health are planned.[[3]]
Only investigations and treatments performed during the index admission were considered and it is unknown whether patients had investigations after discharge. Additionally, some patients may have been assessed using non-invasive means, such as CT coronary angiogram.[[12]]
Policy implications
For patients who present to rural hospitals or urban non-interventional hospitals, especially those who are Māori or Pacific, there are ongoing inequities in the timing of angiography and the assessment of LVEF. However, despite these inequities, the category of hospital that a patient presented to didn’t impact mortality or major adverse cardiac events up to 1 year post-NSTEACS.[[2]] This lack of difference in outcomes might reflect the high prescription rates of secondary medications observed in all three categories of hospital.
The success of quality improvement programmes such as ANZACS-QI is well documented, and ongoing reporting of guideline-driven performance measures should consider differentiation of rural and urban areas and include analyses by ethnicity. These differences are often larger than the differences between regions.[[2,30]]
Addressing the mechanisms that facilitate timely (but not necessarily immediate) inter-hospital transfer for investigations in patients with NSTEACS should be a priority for Te Whatu Ora – Health New Zealand and Te Aka Whai Ora – Māori Health Authority to ensure that evidence-based investigations and interventions are performed. In particular, clinicians in urban hospitals with ready access to echocardiography should ensure that this is performed before the patient is discharged back to a provincial or rural location, where this investigation might be harder to access. A robust national registry for echocardiography is also required.
Conclusion
Patients who present to rural hospitals or urban non-interventional hospitals are less likely to receive angiography within 3 days or an assessment of LVEF. Fewer Māori received angiography within 3 days regardless of the category of hospital presentation. There are high levels of the prescribing of secondary prevention medications across all three hospital categories.
View Appendices.
Summary
Abstract
Aim
Compare the care patients with non-ST segment elevation acute coronary syndrome (NSTEACS) received in Aotearoa New Zealand depending on the rural–urban category of the hospital they are first admitted to.
Method
Patients with NSTEACS investigated with invasive coronary angiogram between 1 January 2014 and 31 December 2019 were included. There were three hospital categories (routine access to percutaneous coronary intervention [urban interventional], other urban [urban non-interventional] and rural) and three ethnicity categories (Māori, Pacific and non-Māori/non-Pacific). Clinical performance measures included: angiography ≤3 days, assessment of left ventricular ejection fraction (LVEF) and prescription of secondary prevention medication.
Results
Of 26,779 patients, 66.2% presented to urban-interventional, 25.6% to urban non-interventional and 8.2% to rural hospitals. A smaller percentage of patients presenting to urban interventional than urban non-interventional and rural hospitals were Māori (8.1%, 17.0% and 13.0%). Patients presenting to urban interventional hospitals were more likely to receive timely angiography than urban non-interventional or rural hospitals (78.5%, 60.8% and 63.1%). They were also more likely to have a LVEF assessment (78.5%, 65.4% and 66.3%). In contrast, the use of secondary prevention medications at discharge was similar between hospital categories.
Māori and Pacific patients presenting to urban interventional hospitals were less likely than non-Māori/non-Pacific to receive timely angiography but more likely to have LVEF assessed. However, LVEF assessment and timely angiography in urban non-interventional and rural hospitals were lower than in urban interventional hospitals for both Māori and non-Māori/non-Pacific.
Conclusion
Patients presenting to urban hospitals without routine interventional access and rural hospitals were less likely to receive LVEF assessment or timely angiography. This disproportionately impacts Māori, who are more likely to live in these hospital catchments.
Author Information
Acknowledgements
Correspondence
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Competing Interests
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Investigation and treatment after non-ST segment elevation acute coronary syndrome for patients presenting to rural or urban hospitals in Aotearoa New Zealand: ANZACS-QI 75
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In Aotearoa New Zealand, patients with non ST-segment elevation acute coronary syndrome (NSTEACS) may present to one of three main groups of hospitals: urban hospitals i) with (interventional) or ii) without (non-interventional) routine access to percutaneous intervention (PCI), or iii) rural hospitals.[[1,2]] Hospitals without routine access to PCI typically have smaller catchments that include a higher proportion of Māori.[[3]] Rural hospitals usually have fewer resources and are at a distance (40 minutes to 4 hours by road) to urban hospitals.[[4]]
Patients who present to hospitals without access to PCI will receive initial treatment at that facility. Stable patients in urban hospitals or larger rural hospitals may be admitted to that facility while awaiting transfer for invasive coronary angiography (angiography hereafter) and further treatment. Unstable patients or those who present to rural hospitals that have fewer resources may require early transfer to a larger hospital. Patients may undergo several hospital transfers to receive definitive care.[[5]]
For patients with NSTEACS, guidelines recommend that angiography is performed within 3 days for all but very low-risk patients (Aotearoa New Zealand target is 70%), that there should be an assessment of left ventricular function (Aotearoa New Zealand target is 85%) and secondary preventative medications are prescribed (Aotearoa New Zealand target is 85%).[[6–8]]
Recent data from Aotearoa New Zealand show that patients with ST elevation myocardial infarction (STEMI) and NSTEACS that present to urban non-interventional or rural hospitals were less likely to receive angiography, but there are no differences in mortality (up to 1 year) and few differences in readmissions to hospitals with adverse cardiac events, heart failure or major bleeding.[[1,2]] However, regardless of the type of hospital at presentation, Māori have higher mortality following STEMI and NSTEACS compared to non-Māori, non-Pacific peoples and have reduced access to invasive cardiac investigations.[[9]] These inequities are more pronounced for Māori that live in rural areas.[[9,10]] There are few data on the investigations and treatments provided to patients that present to Aotearoa New Zealand rural hospitals with NSTEACS.
The aim of this study was therefore to determine if there were differences in the inpatient investigations and treatments that patients received during an admission with NSTEACS associated with the category of hospital (rural, urban non-interventional or urban interventional) that the patient presented to, and to explore any interactions with ethnicity.
Methods
All first admissions to Aotearoa New Zealand public hospitals for patients aged 20 or older with NSTEACS entered in the All New Zealand Acute Coronary Syndrome Quality Improvement (ANZACS-QI) programme between 1 January 2014 and 31 December 2019 were included in the study.
The ANZACS-QI ACS-CathPCI registry was used, which captures in-depth data on the subset of patients that have acute coronary syndrome (ACS) and receive a coronary angiogram in Aotearoa New Zealand public hospitals (approximately 60% of patients with NSTEACS).[[1,2,11,12]]
Hospitals were identified using the facility code assigned by the New Zealand Ministry of Health and divided into three urban–rural hospital categories (Table 1):[[1,2]]
1. Urban hospitals with routine access to PCI (urban interventional)
2. Urban hospitals without routine access to PCI (urban non-interventional), or
3. Rural hospitals
Patients were assigned to the first hospital of presentation. To account for the movement of patients between hospitals, admission events were bundled together.[[12]]
View Tables 1–4, Figures 1–3.
Clinical performance measures
Clinical performance measures that were considered included: invasive coronary angiography performed within 3 days of first presentation; an assessment of the left ventricular ejection fraction (LVEF); and whether the following medications were prescribed at discharge—aspirin, dual antiplatelet therapy (DAPT), statin, angiotensin-converting enzyme inhibitor or angiotensin receptor blocker (ACEi/ARB) and beta-blockers. These were selected as key indicators of quality care and are consistent with Aotearoa New Zealand ACS targets, as well as Australasian and international guidelines and existing literature.[[6–8]]
Data collected
Age, sex, prioritised ethnicity categorised as Māori, Pacific and non-Māori, non-Pacific peoples (using the Ministry of Health’s protocols),[[13]] body mass index (BMI), smoking status, history of diabetes, congestive heart failure (CHF), prior cardiovascular disease, renal dialysis, admission heart rate (HR) and systolic blood pressure (SBP), low density lipoprotein cholesterol concentration (LDL), initial Killip group,[[14]] cardiac arrest on arrival, estimated glomerular filtration rate (eGFR), Grace score[[15]] and anticoagulant use were collected.
Clinical information included: the time from arrival at the hospital of presentation to angiography (in days); assessment of the LVEF, either by echocardiogram or left ventricular angiogram; findings from angiogram and LVEF assessment; whether PCI was performed; and if there was a referral for (inpatient or outpatient) coronary artery bypass grafting.
The prescription of, or documented contra-indication, to aspirin, another antiplatelet agent, statin, angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB) or beta-blockers were recorded. Patients were considered to have been prescribed dual antiplatelet therapy if they had both aspirin and a second antiplatelet agent prescribed at discharge.
Statistical analysis
Data were summarised using mean and standard deviation (SD) for continuous data and frequency and percentage for categorical data, overall and by hospital category.
Logistic regression, separately for each performance measure, was used to estimate the odds ratios (OR) with 95% confidence intervals (95% CI) comparing urban non-interventional and rural hospitals with urban interventional hospitals (reference group). A binary outcome was created for the prescription of a medication where “prescribed” or “contra-indication” were re-categorised as “true”.
For all models, the following potential confounders of hospital category were included: sex, ethnicity, age, type of NSTEACS, current smoker, prior cardiovascular event, history of diabetes, BMI, HR, SBP, Killip group, LDL, eGFR, history of CHF, health region (Northern, Te Manawa Taki, Central, Southern) and anticoagulant use. LVEF assessment and the findings from this assessment were both considered additional confounders in the models for angiography that occurred within 3 days and prescription of secondary preventative medications. Angiography within 3 days was considered a confounder in the models for LVEF assessment and the prescription of secondary prevention medications.
All model assumptions were checked. Complex non-linear associations were dealt with by categorisation as follows: age (20–44 years, 45–59 years, 60–69 years, 70–89 years and 90+ years); BMI (<18, 18.5–24.9, 25–29.9, 30–34.9 and 35+), heart rate (<50, 50–99, 100–149 and >150 beats per minute); SBP ( <100, 100–149, 150–200 and 201+ mmHg) and LDL (0–1.9, 2–3.9, 4–5.9 and 6+ mmol/L).
Backwards elimination was used to identify and remove non-significant confounders; however, important confounders (age, ethnicity) were retained regardless of significance. Likelihood ratio tests were used to assess the significance of each variable in the model. Only a priori interactions (age and ethnicity) were investigated.
Large amounts (>10%) of missing data within a single variable were categorised and coded as a separate category and included in the regression models. A sensitivity analysis was performed comparing this method with multiple imputation (Appendix 4).
All analyses were performed in R (version 4.1.1) using R-Studio (22.02.3 Boston, MA).[[16]]
Ethics
The ANZACS-QI study is part of a programme of research originally approved by the Northern Region Ethics Committee in 2003 (AKY/03/12/314), with subsequent approval by the National Multi Region Ethics Committee in 2007 (MEC07/19/EXP) and with annual re-approval since as part of a vascular research programme (2022 EXP 13442). Individual patient consent was not required as all data are de-identified.[[11]]
Results
There were 26,779 patients with NSTEACS between 2014 and 2019. Patient characteristics are presented in Table 2. Most patients (66.2%) presented to urban interventional hospitals, with a quarter of patients presenting to urban non-interventional (25.6%) and 8.2% to rural hospitals. A lower percentage of patients that presented to urban interventional hospitals were Māori, compared to urban non-interventional and rural hospitals (8.1%, 17.0% and 13.0% respectively); however, the reverse occurred for Pacific peoples (7.1%, 1.4% and 1.7%). Compared with interventional hospitals, patients that presented to non-interventional and rural hospitals were also more likely to be older (mean age: 65.6 years, 66.4 years and 67 years respectively) and female (30.4%, 34.8% and 33%).
Findings (including ORs) for the process measures angiography within 3 days and assessment of LVEF are shown in Table 3 and Figure 1. There was a significant (p<0.001) interaction between ethnicity and category of hospital for both these two outcome measures.
Invasive coronary angiography within 3 days
Overall, 72.7% of patients received angiography within 3 days; of this, a higher percentage were patients that presented to urban interventional hospitals (78.5%) than rural (60.8%) and urban non-interventional hospitals (63.8%).
For patients presenting to urban interventional hospitals, a lower percentage of Māori (74.3%, OR: 0.78, 95% CI: 0.68 to 0.89) and Pacific peoples (69.3%, OR: 0.75, 95% CI: 0.65 to 0.86) received this investigation compared with non-Māori, non-Pacific peoples (79.8%). For all patients that presented to rural or urban non-interventional hospitals, fewer patients received angiography within 3 days.
Figure 2 shows the time to angiography for each ethnicity and hospital of presentation category.
Assessment of LVEF
Overall, 74.1% of patients received an assessment of LVEF. This percentage was higher for urban interventional (78.5%) compared with rural (66.6%) and urban non-interventional hospitals (65.4%).
A higher percentage of Māori (82.7%, OR: 1.30, 95% CI: 1.12 to 1.51) and Pacific (85.5%, OR: 1.35, 95% CI: 1.14 to 1.62) patients that presented to urban interventional hospitals received an assessment of LVEF compared with non-Māori, non-Pacific peoples (77.5%). However, fewer Māori who presented to urban non-interventional hospitals (68.8%, OR: 0.61, 95% CI: 0.53 to 0.71) and rural hospitals (63.2%, OR: 0.40, 95% CI: 0.31 to 0.52) received this investigation. Similarly, compared to non-Māori, non-Pacific peoples presenting to urban interventional hospitals, fewer non-Māori, non-Pacific peoples who presented to rural hospitals (66.6%, OR: 0.56, 95% CI: 0.50 to 0.62) or urban non-interventional hospitals (64.7%, OR: 0.54, 95% CI: 0.50 to 0.58) received an assessment of the LVEF.
The measured LVEF and the angiography findings were similar across the three categories of hospital and are shown in Appendix 1.
Prescription of secondary prevention medications
Figure 3 and Table 4 present the number, percentage and the unadjusted and adjusted ORs for the prescription of secondary prevention medications at discharge. There were no interactions identified.
Most patients received secondary prevention medications. Nearly all patients had a prescription for aspirin (96.1%), with slightly fewer patients who presented to rural hospitals (95.5%, OR: 0.66, 95% CI: 0.52 to 0.85) or urban non-interventional hospitals (95.1%, OR: 0.89, 95% CI: 0.75 to 1.05) receiving this prescription. A higher percentage of patients that presented to rural hospitals or urban non-interventional hospitals were prescribed beta-blockers (88.3%, OR: 1.34, 95% CI: 1.16 to 1.54 and 86.3%, OR: 1.40, 95% CI: 1.28 to 1.53 respectively) compared with urban interventional hospitals (84.3%).
Adjusting for hospital category of presentation, with the exception of ACEi/ARB (Māori 74.3%, Pacific 78.9%, non-Māori non-Pacific 71.0%), there were no clinically significant differences in the percentage of patients that received a prescription of secondary preventative medication between the three ethnic groups (Appendix 2 and 3).
There were large amounts of missing data (23.5%) for the BMI variable. There were no major differences in the interpretation in any of the outcomes after substituting missing values using multiple imputation (Appendix 4).
Discussion
This national study using the ANZACS-QI registry shows that fewer patients (61% and 63%) who presented to rural hospitals or urban non-interventional hospitals had angiography within 3 days of presentation (and therefore the opportunity for intervention) compared with patients who presented to urban interventional hospitals (78.5%). Only patients presenting to urban interventional hospitals met the Aotearoa New Zealand target of 70%.[[8]] In urban interventional hospitals, Māori and Pacific patients were less likely to receive this investigation within 3 days than non-Māori, non-Pacific patients.
A higher percentage of Māori and Pacific patients that presented to urban interventional hospitals received an assessment of the LVEF compared with non-Māori, non-Pacific patients. However, regardless of ethnicity, patients that presented to rural hospitals or urban non-interventional hospitals were less likely to receive this investigation. The Aotearoa New Zealand target (85%) was only met for Pacific peoples presenting to urban interventional hospitals. Overall, the rates of prescribing for secondary prevention medication at discharge were high.
Invasive coronary angiography
That patients presenting with NSTEACS to rural hospitals or urban non-interventional hospitals waited longer to receive angiography is consistent with Aotearoa New Zealand data in patients diagnosed with STEMI.[[1]] Other Aotearoa New Zealand studies show a similar trend, where patients that presented with NSTEACS in district health boards (DHBs) without PCI capabilities were also less likely to have angiography within 3 days.[[17]] These studies did not differentiate rural from urban hospitals and some DHBs will have included hospitals with and without interventional facilities (e.g., Southern).
Inequities in providing timely angiography for Māori and other Indigenous peoples are well documented.[[9,18]] Our study shows that, regardless of where they present, Māori with NSTEACS wait longer for angiography compared to non-Māori, non-Pacific patients. This disadvantage is worsened for Māori and Pacific peoples who live in urban non-interventional and rural catchments. One potential explanation is the historical lack of angiographic capacity in hospitals that serve large Māori and Pacific populations. We might anticipate this situation could improve with the recent addition of cardiac catheter laboratories to both Whangārei and Middlemore hospitals.[[19]] It is also likely that institutional racism and biases at multiple levels contribute to the inequities for Māori and Pacific peoples seen in our study.[[2,9,20]]
Assessment of LVEF
Access to echocardiography varies throughout Aotearoa New Zealand. Hospitals that do not have cardiothoracic services are less likely to offer this investigation.[[21–23]] Our study shows that patients from urban non-interventional or rural catchments are significantly less likely to have LVEF assessment during their admission, even though all patients were transferred to an interventional centre. This is likely due to a service focus on delivering angiography and maintaining rapid patient throughput in these interventional centres, with patients waiting in rural and urban non-interventional hospitals where access to echocardiography is limited. This finding of fewer patients receiving LVEF assessment in non-interventional hospitals has been previously seen in Australian and Aotearoa New Zealand data.[[24]] The percentage of patients that presented to these non-interventional hospitals in Aotearoa New Zealand and received an LVEF assessment lags behind many other countries and regions (e.g., Israel 72–87.9%, Europe 78–93%, China 81%).[[25,26]]
A higher percentage of Māori and Pacific patients who presented to urban interventional hospitals received an assessment of LVEF compared with non-Māori, non-Pacific peoples; however, this was not apparent for Māori who presented to rural hospitals or urban non-interventional hospitals. This is the opposite situation to coronary angiography. The discrepancy could be explained by the presence of well-developed echocardiographic services but the lack of angiography capacity in hospital catchments with large Māori and Pacific populations. Māori patients are also more likely to present with NSTEACS complicated by cardiac arrest or heart failure. In this situation, echocardiography (but not angiography) is prioritised.[[20]] Where echocardiography is less available, this prioritisation is not possible.
Secondary prevention medication
Regardless of the type of hospital patients presented to, the majority received discharge prescriptions for guideline-directed secondary preventative medications.
While the high overall rate of prescription of these medications is consistent with other Aotearoa New Zealand studies,[[27,28]] our results are in contrast to international data that shows patients from smaller regional and rural places who have NSTEACS were less likely to receive guideline-directed medications.[[24]] The lack of meaningful difference in prescribing at the point of discharge between hospital categories doesn’t explain the small increase in 2-year mortality seen in a previous study,[[2]] although long-term maintenance of these medications for patients who live in rural areas requires further examination.
Patients were more likely to get a prescription for beta-blockers if they presented to rural hospitals or urban non-interventional hospitals. International guidelines acknowledge the role of beta-blockers after NSTEACS in patients with reduced ejection fraction,[[6]] but the role of beta-blockers is uncertain in patients with preserved ejection fraction.[[29]] This uncertainty may be reflected in the prescribing of specialist cardiologists but not of more generalist doctors, who are also less likely to know the patient’s LVEF due to the unavailability of echocardiography. In those that did get echocardiography, there were no differences in the measured LVEF between hospital groups.
Strengths and weaknesses
The strength of this study is the use of the ANZACS-QI Cath-PCI registry. This has a high level of capture of patients that receive angiography.[[12]] A potential limitation is that any investigations (e.g., echocardiography) or treatments (including secondary prevention medications) that patients who didn’t receive angiography (approximately 40% of patients with NSTEACS) may have accessed were not able to be included in the analysis.[[2,17]] Additionally, patients were not risk stratified to determine when angiography should occur according to guidelines (e.g., high-risk patients should have angiography within 24 hours).[[6]] This could be reviewed in future studies. A composite medication outcome wasn’t used for this study and so no comparison could be made with the Aotearoa New Zealand target of 85% for this outcome measure.
This study focusses on which type of hospitals patients present to, rather than the rural–urban category of their usual residence. Future studies using the Geographic Classification for Health are planned.[[3]]
Only investigations and treatments performed during the index admission were considered and it is unknown whether patients had investigations after discharge. Additionally, some patients may have been assessed using non-invasive means, such as CT coronary angiogram.[[12]]
Policy implications
For patients who present to rural hospitals or urban non-interventional hospitals, especially those who are Māori or Pacific, there are ongoing inequities in the timing of angiography and the assessment of LVEF. However, despite these inequities, the category of hospital that a patient presented to didn’t impact mortality or major adverse cardiac events up to 1 year post-NSTEACS.[[2]] This lack of difference in outcomes might reflect the high prescription rates of secondary medications observed in all three categories of hospital.
The success of quality improvement programmes such as ANZACS-QI is well documented, and ongoing reporting of guideline-driven performance measures should consider differentiation of rural and urban areas and include analyses by ethnicity. These differences are often larger than the differences between regions.[[2,30]]
Addressing the mechanisms that facilitate timely (but not necessarily immediate) inter-hospital transfer for investigations in patients with NSTEACS should be a priority for Te Whatu Ora – Health New Zealand and Te Aka Whai Ora – Māori Health Authority to ensure that evidence-based investigations and interventions are performed. In particular, clinicians in urban hospitals with ready access to echocardiography should ensure that this is performed before the patient is discharged back to a provincial or rural location, where this investigation might be harder to access. A robust national registry for echocardiography is also required.
Conclusion
Patients who present to rural hospitals or urban non-interventional hospitals are less likely to receive angiography within 3 days or an assessment of LVEF. Fewer Māori received angiography within 3 days regardless of the category of hospital presentation. There are high levels of the prescribing of secondary prevention medications across all three hospital categories.
View Appendices.
Summary
Abstract
Aim
Compare the care patients with non-ST segment elevation acute coronary syndrome (NSTEACS) received in Aotearoa New Zealand depending on the rural–urban category of the hospital they are first admitted to.
Method
Patients with NSTEACS investigated with invasive coronary angiogram between 1 January 2014 and 31 December 2019 were included. There were three hospital categories (routine access to percutaneous coronary intervention [urban interventional], other urban [urban non-interventional] and rural) and three ethnicity categories (Māori, Pacific and non-Māori/non-Pacific). Clinical performance measures included: angiography ≤3 days, assessment of left ventricular ejection fraction (LVEF) and prescription of secondary prevention medication.
Results
Of 26,779 patients, 66.2% presented to urban-interventional, 25.6% to urban non-interventional and 8.2% to rural hospitals. A smaller percentage of patients presenting to urban interventional than urban non-interventional and rural hospitals were Māori (8.1%, 17.0% and 13.0%). Patients presenting to urban interventional hospitals were more likely to receive timely angiography than urban non-interventional or rural hospitals (78.5%, 60.8% and 63.1%). They were also more likely to have a LVEF assessment (78.5%, 65.4% and 66.3%). In contrast, the use of secondary prevention medications at discharge was similar between hospital categories.
Māori and Pacific patients presenting to urban interventional hospitals were less likely than non-Māori/non-Pacific to receive timely angiography but more likely to have LVEF assessed. However, LVEF assessment and timely angiography in urban non-interventional and rural hospitals were lower than in urban interventional hospitals for both Māori and non-Māori/non-Pacific.
Conclusion
Patients presenting to urban hospitals without routine interventional access and rural hospitals were less likely to receive LVEF assessment or timely angiography. This disproportionately impacts Māori, who are more likely to live in these hospital catchments.
Author Information
Acknowledgements
Correspondence
Correspondence Email
Competing Interests
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Investigation and treatment after non-ST segment elevation acute coronary syndrome for patients presenting to rural or urban hospitals in Aotearoa New Zealand: ANZACS-QI 75
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In Aotearoa New Zealand, patients with non ST-segment elevation acute coronary syndrome (NSTEACS) may present to one of three main groups of hospitals: urban hospitals i) with (interventional) or ii) without (non-interventional) routine access to percutaneous intervention (PCI), or iii) rural hospitals.[[1,2]] Hospitals without routine access to PCI typically have smaller catchments that include a higher proportion of Māori.[[3]] Rural hospitals usually have fewer resources and are at a distance (40 minutes to 4 hours by road) to urban hospitals.[[4]]
Patients who present to hospitals without access to PCI will receive initial treatment at that facility. Stable patients in urban hospitals or larger rural hospitals may be admitted to that facility while awaiting transfer for invasive coronary angiography (angiography hereafter) and further treatment. Unstable patients or those who present to rural hospitals that have fewer resources may require early transfer to a larger hospital. Patients may undergo several hospital transfers to receive definitive care.[[5]]
For patients with NSTEACS, guidelines recommend that angiography is performed within 3 days for all but very low-risk patients (Aotearoa New Zealand target is 70%), that there should be an assessment of left ventricular function (Aotearoa New Zealand target is 85%) and secondary preventative medications are prescribed (Aotearoa New Zealand target is 85%).[[6–8]]
Recent data from Aotearoa New Zealand show that patients with ST elevation myocardial infarction (STEMI) and NSTEACS that present to urban non-interventional or rural hospitals were less likely to receive angiography, but there are no differences in mortality (up to 1 year) and few differences in readmissions to hospitals with adverse cardiac events, heart failure or major bleeding.[[1,2]] However, regardless of the type of hospital at presentation, Māori have higher mortality following STEMI and NSTEACS compared to non-Māori, non-Pacific peoples and have reduced access to invasive cardiac investigations.[[9]] These inequities are more pronounced for Māori that live in rural areas.[[9,10]] There are few data on the investigations and treatments provided to patients that present to Aotearoa New Zealand rural hospitals with NSTEACS.
The aim of this study was therefore to determine if there were differences in the inpatient investigations and treatments that patients received during an admission with NSTEACS associated with the category of hospital (rural, urban non-interventional or urban interventional) that the patient presented to, and to explore any interactions with ethnicity.
Methods
All first admissions to Aotearoa New Zealand public hospitals for patients aged 20 or older with NSTEACS entered in the All New Zealand Acute Coronary Syndrome Quality Improvement (ANZACS-QI) programme between 1 January 2014 and 31 December 2019 were included in the study.
The ANZACS-QI ACS-CathPCI registry was used, which captures in-depth data on the subset of patients that have acute coronary syndrome (ACS) and receive a coronary angiogram in Aotearoa New Zealand public hospitals (approximately 60% of patients with NSTEACS).[[1,2,11,12]]
Hospitals were identified using the facility code assigned by the New Zealand Ministry of Health and divided into three urban–rural hospital categories (Table 1):[[1,2]]
1. Urban hospitals with routine access to PCI (urban interventional)
2. Urban hospitals without routine access to PCI (urban non-interventional), or
3. Rural hospitals
Patients were assigned to the first hospital of presentation. To account for the movement of patients between hospitals, admission events were bundled together.[[12]]
View Tables 1–4, Figures 1–3.
Clinical performance measures
Clinical performance measures that were considered included: invasive coronary angiography performed within 3 days of first presentation; an assessment of the left ventricular ejection fraction (LVEF); and whether the following medications were prescribed at discharge—aspirin, dual antiplatelet therapy (DAPT), statin, angiotensin-converting enzyme inhibitor or angiotensin receptor blocker (ACEi/ARB) and beta-blockers. These were selected as key indicators of quality care and are consistent with Aotearoa New Zealand ACS targets, as well as Australasian and international guidelines and existing literature.[[6–8]]
Data collected
Age, sex, prioritised ethnicity categorised as Māori, Pacific and non-Māori, non-Pacific peoples (using the Ministry of Health’s protocols),[[13]] body mass index (BMI), smoking status, history of diabetes, congestive heart failure (CHF), prior cardiovascular disease, renal dialysis, admission heart rate (HR) and systolic blood pressure (SBP), low density lipoprotein cholesterol concentration (LDL), initial Killip group,[[14]] cardiac arrest on arrival, estimated glomerular filtration rate (eGFR), Grace score[[15]] and anticoagulant use were collected.
Clinical information included: the time from arrival at the hospital of presentation to angiography (in days); assessment of the LVEF, either by echocardiogram or left ventricular angiogram; findings from angiogram and LVEF assessment; whether PCI was performed; and if there was a referral for (inpatient or outpatient) coronary artery bypass grafting.
The prescription of, or documented contra-indication, to aspirin, another antiplatelet agent, statin, angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB) or beta-blockers were recorded. Patients were considered to have been prescribed dual antiplatelet therapy if they had both aspirin and a second antiplatelet agent prescribed at discharge.
Statistical analysis
Data were summarised using mean and standard deviation (SD) for continuous data and frequency and percentage for categorical data, overall and by hospital category.
Logistic regression, separately for each performance measure, was used to estimate the odds ratios (OR) with 95% confidence intervals (95% CI) comparing urban non-interventional and rural hospitals with urban interventional hospitals (reference group). A binary outcome was created for the prescription of a medication where “prescribed” or “contra-indication” were re-categorised as “true”.
For all models, the following potential confounders of hospital category were included: sex, ethnicity, age, type of NSTEACS, current smoker, prior cardiovascular event, history of diabetes, BMI, HR, SBP, Killip group, LDL, eGFR, history of CHF, health region (Northern, Te Manawa Taki, Central, Southern) and anticoagulant use. LVEF assessment and the findings from this assessment were both considered additional confounders in the models for angiography that occurred within 3 days and prescription of secondary preventative medications. Angiography within 3 days was considered a confounder in the models for LVEF assessment and the prescription of secondary prevention medications.
All model assumptions were checked. Complex non-linear associations were dealt with by categorisation as follows: age (20–44 years, 45–59 years, 60–69 years, 70–89 years and 90+ years); BMI (<18, 18.5–24.9, 25–29.9, 30–34.9 and 35+), heart rate (<50, 50–99, 100–149 and >150 beats per minute); SBP ( <100, 100–149, 150–200 and 201+ mmHg) and LDL (0–1.9, 2–3.9, 4–5.9 and 6+ mmol/L).
Backwards elimination was used to identify and remove non-significant confounders; however, important confounders (age, ethnicity) were retained regardless of significance. Likelihood ratio tests were used to assess the significance of each variable in the model. Only a priori interactions (age and ethnicity) were investigated.
Large amounts (>10%) of missing data within a single variable were categorised and coded as a separate category and included in the regression models. A sensitivity analysis was performed comparing this method with multiple imputation (Appendix 4).
All analyses were performed in R (version 4.1.1) using R-Studio (22.02.3 Boston, MA).[[16]]
Ethics
The ANZACS-QI study is part of a programme of research originally approved by the Northern Region Ethics Committee in 2003 (AKY/03/12/314), with subsequent approval by the National Multi Region Ethics Committee in 2007 (MEC07/19/EXP) and with annual re-approval since as part of a vascular research programme (2022 EXP 13442). Individual patient consent was not required as all data are de-identified.[[11]]
Results
There were 26,779 patients with NSTEACS between 2014 and 2019. Patient characteristics are presented in Table 2. Most patients (66.2%) presented to urban interventional hospitals, with a quarter of patients presenting to urban non-interventional (25.6%) and 8.2% to rural hospitals. A lower percentage of patients that presented to urban interventional hospitals were Māori, compared to urban non-interventional and rural hospitals (8.1%, 17.0% and 13.0% respectively); however, the reverse occurred for Pacific peoples (7.1%, 1.4% and 1.7%). Compared with interventional hospitals, patients that presented to non-interventional and rural hospitals were also more likely to be older (mean age: 65.6 years, 66.4 years and 67 years respectively) and female (30.4%, 34.8% and 33%).
Findings (including ORs) for the process measures angiography within 3 days and assessment of LVEF are shown in Table 3 and Figure 1. There was a significant (p<0.001) interaction between ethnicity and category of hospital for both these two outcome measures.
Invasive coronary angiography within 3 days
Overall, 72.7% of patients received angiography within 3 days; of this, a higher percentage were patients that presented to urban interventional hospitals (78.5%) than rural (60.8%) and urban non-interventional hospitals (63.8%).
For patients presenting to urban interventional hospitals, a lower percentage of Māori (74.3%, OR: 0.78, 95% CI: 0.68 to 0.89) and Pacific peoples (69.3%, OR: 0.75, 95% CI: 0.65 to 0.86) received this investigation compared with non-Māori, non-Pacific peoples (79.8%). For all patients that presented to rural or urban non-interventional hospitals, fewer patients received angiography within 3 days.
Figure 2 shows the time to angiography for each ethnicity and hospital of presentation category.
Assessment of LVEF
Overall, 74.1% of patients received an assessment of LVEF. This percentage was higher for urban interventional (78.5%) compared with rural (66.6%) and urban non-interventional hospitals (65.4%).
A higher percentage of Māori (82.7%, OR: 1.30, 95% CI: 1.12 to 1.51) and Pacific (85.5%, OR: 1.35, 95% CI: 1.14 to 1.62) patients that presented to urban interventional hospitals received an assessment of LVEF compared with non-Māori, non-Pacific peoples (77.5%). However, fewer Māori who presented to urban non-interventional hospitals (68.8%, OR: 0.61, 95% CI: 0.53 to 0.71) and rural hospitals (63.2%, OR: 0.40, 95% CI: 0.31 to 0.52) received this investigation. Similarly, compared to non-Māori, non-Pacific peoples presenting to urban interventional hospitals, fewer non-Māori, non-Pacific peoples who presented to rural hospitals (66.6%, OR: 0.56, 95% CI: 0.50 to 0.62) or urban non-interventional hospitals (64.7%, OR: 0.54, 95% CI: 0.50 to 0.58) received an assessment of the LVEF.
The measured LVEF and the angiography findings were similar across the three categories of hospital and are shown in Appendix 1.
Prescription of secondary prevention medications
Figure 3 and Table 4 present the number, percentage and the unadjusted and adjusted ORs for the prescription of secondary prevention medications at discharge. There were no interactions identified.
Most patients received secondary prevention medications. Nearly all patients had a prescription for aspirin (96.1%), with slightly fewer patients who presented to rural hospitals (95.5%, OR: 0.66, 95% CI: 0.52 to 0.85) or urban non-interventional hospitals (95.1%, OR: 0.89, 95% CI: 0.75 to 1.05) receiving this prescription. A higher percentage of patients that presented to rural hospitals or urban non-interventional hospitals were prescribed beta-blockers (88.3%, OR: 1.34, 95% CI: 1.16 to 1.54 and 86.3%, OR: 1.40, 95% CI: 1.28 to 1.53 respectively) compared with urban interventional hospitals (84.3%).
Adjusting for hospital category of presentation, with the exception of ACEi/ARB (Māori 74.3%, Pacific 78.9%, non-Māori non-Pacific 71.0%), there were no clinically significant differences in the percentage of patients that received a prescription of secondary preventative medication between the three ethnic groups (Appendix 2 and 3).
There were large amounts of missing data (23.5%) for the BMI variable. There were no major differences in the interpretation in any of the outcomes after substituting missing values using multiple imputation (Appendix 4).
Discussion
This national study using the ANZACS-QI registry shows that fewer patients (61% and 63%) who presented to rural hospitals or urban non-interventional hospitals had angiography within 3 days of presentation (and therefore the opportunity for intervention) compared with patients who presented to urban interventional hospitals (78.5%). Only patients presenting to urban interventional hospitals met the Aotearoa New Zealand target of 70%.[[8]] In urban interventional hospitals, Māori and Pacific patients were less likely to receive this investigation within 3 days than non-Māori, non-Pacific patients.
A higher percentage of Māori and Pacific patients that presented to urban interventional hospitals received an assessment of the LVEF compared with non-Māori, non-Pacific patients. However, regardless of ethnicity, patients that presented to rural hospitals or urban non-interventional hospitals were less likely to receive this investigation. The Aotearoa New Zealand target (85%) was only met for Pacific peoples presenting to urban interventional hospitals. Overall, the rates of prescribing for secondary prevention medication at discharge were high.
Invasive coronary angiography
That patients presenting with NSTEACS to rural hospitals or urban non-interventional hospitals waited longer to receive angiography is consistent with Aotearoa New Zealand data in patients diagnosed with STEMI.[[1]] Other Aotearoa New Zealand studies show a similar trend, where patients that presented with NSTEACS in district health boards (DHBs) without PCI capabilities were also less likely to have angiography within 3 days.[[17]] These studies did not differentiate rural from urban hospitals and some DHBs will have included hospitals with and without interventional facilities (e.g., Southern).
Inequities in providing timely angiography for Māori and other Indigenous peoples are well documented.[[9,18]] Our study shows that, regardless of where they present, Māori with NSTEACS wait longer for angiography compared to non-Māori, non-Pacific patients. This disadvantage is worsened for Māori and Pacific peoples who live in urban non-interventional and rural catchments. One potential explanation is the historical lack of angiographic capacity in hospitals that serve large Māori and Pacific populations. We might anticipate this situation could improve with the recent addition of cardiac catheter laboratories to both Whangārei and Middlemore hospitals.[[19]] It is also likely that institutional racism and biases at multiple levels contribute to the inequities for Māori and Pacific peoples seen in our study.[[2,9,20]]
Assessment of LVEF
Access to echocardiography varies throughout Aotearoa New Zealand. Hospitals that do not have cardiothoracic services are less likely to offer this investigation.[[21–23]] Our study shows that patients from urban non-interventional or rural catchments are significantly less likely to have LVEF assessment during their admission, even though all patients were transferred to an interventional centre. This is likely due to a service focus on delivering angiography and maintaining rapid patient throughput in these interventional centres, with patients waiting in rural and urban non-interventional hospitals where access to echocardiography is limited. This finding of fewer patients receiving LVEF assessment in non-interventional hospitals has been previously seen in Australian and Aotearoa New Zealand data.[[24]] The percentage of patients that presented to these non-interventional hospitals in Aotearoa New Zealand and received an LVEF assessment lags behind many other countries and regions (e.g., Israel 72–87.9%, Europe 78–93%, China 81%).[[25,26]]
A higher percentage of Māori and Pacific patients who presented to urban interventional hospitals received an assessment of LVEF compared with non-Māori, non-Pacific peoples; however, this was not apparent for Māori who presented to rural hospitals or urban non-interventional hospitals. This is the opposite situation to coronary angiography. The discrepancy could be explained by the presence of well-developed echocardiographic services but the lack of angiography capacity in hospital catchments with large Māori and Pacific populations. Māori patients are also more likely to present with NSTEACS complicated by cardiac arrest or heart failure. In this situation, echocardiography (but not angiography) is prioritised.[[20]] Where echocardiography is less available, this prioritisation is not possible.
Secondary prevention medication
Regardless of the type of hospital patients presented to, the majority received discharge prescriptions for guideline-directed secondary preventative medications.
While the high overall rate of prescription of these medications is consistent with other Aotearoa New Zealand studies,[[27,28]] our results are in contrast to international data that shows patients from smaller regional and rural places who have NSTEACS were less likely to receive guideline-directed medications.[[24]] The lack of meaningful difference in prescribing at the point of discharge between hospital categories doesn’t explain the small increase in 2-year mortality seen in a previous study,[[2]] although long-term maintenance of these medications for patients who live in rural areas requires further examination.
Patients were more likely to get a prescription for beta-blockers if they presented to rural hospitals or urban non-interventional hospitals. International guidelines acknowledge the role of beta-blockers after NSTEACS in patients with reduced ejection fraction,[[6]] but the role of beta-blockers is uncertain in patients with preserved ejection fraction.[[29]] This uncertainty may be reflected in the prescribing of specialist cardiologists but not of more generalist doctors, who are also less likely to know the patient’s LVEF due to the unavailability of echocardiography. In those that did get echocardiography, there were no differences in the measured LVEF between hospital groups.
Strengths and weaknesses
The strength of this study is the use of the ANZACS-QI Cath-PCI registry. This has a high level of capture of patients that receive angiography.[[12]] A potential limitation is that any investigations (e.g., echocardiography) or treatments (including secondary prevention medications) that patients who didn’t receive angiography (approximately 40% of patients with NSTEACS) may have accessed were not able to be included in the analysis.[[2,17]] Additionally, patients were not risk stratified to determine when angiography should occur according to guidelines (e.g., high-risk patients should have angiography within 24 hours).[[6]] This could be reviewed in future studies. A composite medication outcome wasn’t used for this study and so no comparison could be made with the Aotearoa New Zealand target of 85% for this outcome measure.
This study focusses on which type of hospitals patients present to, rather than the rural–urban category of their usual residence. Future studies using the Geographic Classification for Health are planned.[[3]]
Only investigations and treatments performed during the index admission were considered and it is unknown whether patients had investigations after discharge. Additionally, some patients may have been assessed using non-invasive means, such as CT coronary angiogram.[[12]]
Policy implications
For patients who present to rural hospitals or urban non-interventional hospitals, especially those who are Māori or Pacific, there are ongoing inequities in the timing of angiography and the assessment of LVEF. However, despite these inequities, the category of hospital that a patient presented to didn’t impact mortality or major adverse cardiac events up to 1 year post-NSTEACS.[[2]] This lack of difference in outcomes might reflect the high prescription rates of secondary medications observed in all three categories of hospital.
The success of quality improvement programmes such as ANZACS-QI is well documented, and ongoing reporting of guideline-driven performance measures should consider differentiation of rural and urban areas and include analyses by ethnicity. These differences are often larger than the differences between regions.[[2,30]]
Addressing the mechanisms that facilitate timely (but not necessarily immediate) inter-hospital transfer for investigations in patients with NSTEACS should be a priority for Te Whatu Ora – Health New Zealand and Te Aka Whai Ora – Māori Health Authority to ensure that evidence-based investigations and interventions are performed. In particular, clinicians in urban hospitals with ready access to echocardiography should ensure that this is performed before the patient is discharged back to a provincial or rural location, where this investigation might be harder to access. A robust national registry for echocardiography is also required.
Conclusion
Patients who present to rural hospitals or urban non-interventional hospitals are less likely to receive angiography within 3 days or an assessment of LVEF. Fewer Māori received angiography within 3 days regardless of the category of hospital presentation. There are high levels of the prescribing of secondary prevention medications across all three hospital categories.
View Appendices.
Summary
Abstract
Aim
Compare the care patients with non-ST segment elevation acute coronary syndrome (NSTEACS) received in Aotearoa New Zealand depending on the rural–urban category of the hospital they are first admitted to.
Method
Patients with NSTEACS investigated with invasive coronary angiogram between 1 January 2014 and 31 December 2019 were included. There were three hospital categories (routine access to percutaneous coronary intervention [urban interventional], other urban [urban non-interventional] and rural) and three ethnicity categories (Māori, Pacific and non-Māori/non-Pacific). Clinical performance measures included: angiography ≤3 days, assessment of left ventricular ejection fraction (LVEF) and prescription of secondary prevention medication.
Results
Of 26,779 patients, 66.2% presented to urban-interventional, 25.6% to urban non-interventional and 8.2% to rural hospitals. A smaller percentage of patients presenting to urban interventional than urban non-interventional and rural hospitals were Māori (8.1%, 17.0% and 13.0%). Patients presenting to urban interventional hospitals were more likely to receive timely angiography than urban non-interventional or rural hospitals (78.5%, 60.8% and 63.1%). They were also more likely to have a LVEF assessment (78.5%, 65.4% and 66.3%). In contrast, the use of secondary prevention medications at discharge was similar between hospital categories.
Māori and Pacific patients presenting to urban interventional hospitals were less likely than non-Māori/non-Pacific to receive timely angiography but more likely to have LVEF assessed. However, LVEF assessment and timely angiography in urban non-interventional and rural hospitals were lower than in urban interventional hospitals for both Māori and non-Māori/non-Pacific.
Conclusion
Patients presenting to urban hospitals without routine interventional access and rural hospitals were less likely to receive LVEF assessment or timely angiography. This disproportionately impacts Māori, who are more likely to live in these hospital catchments.
Author Information
Acknowledgements
Correspondence
Correspondence Email
Competing Interests
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Investigation and treatment after non-ST segment elevation acute coronary syndrome for patients presenting to rural or urban hospitals in Aotearoa New Zealand: ANZACS-QI 75
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In Aotearoa New Zealand, patients with non ST-segment elevation acute coronary syndrome (NSTEACS) may present to one of three main groups of hospitals: urban hospitals i) with (interventional) or ii) without (non-interventional) routine access to percutaneous intervention (PCI), or iii) rural hospitals.[[1,2]] Hospitals without routine access to PCI typically have smaller catchments that include a higher proportion of Māori.[[3]] Rural hospitals usually have fewer resources and are at a distance (40 minutes to 4 hours by road) to urban hospitals.[[4]]
Patients who present to hospitals without access to PCI will receive initial treatment at that facility. Stable patients in urban hospitals or larger rural hospitals may be admitted to that facility while awaiting transfer for invasive coronary angiography (angiography hereafter) and further treatment. Unstable patients or those who present to rural hospitals that have fewer resources may require early transfer to a larger hospital. Patients may undergo several hospital transfers to receive definitive care.[[5]]
For patients with NSTEACS, guidelines recommend that angiography is performed within 3 days for all but very low-risk patients (Aotearoa New Zealand target is 70%), that there should be an assessment of left ventricular function (Aotearoa New Zealand target is 85%) and secondary preventative medications are prescribed (Aotearoa New Zealand target is 85%).[[6–8]]
Recent data from Aotearoa New Zealand show that patients with ST elevation myocardial infarction (STEMI) and NSTEACS that present to urban non-interventional or rural hospitals were less likely to receive angiography, but there are no differences in mortality (up to 1 year) and few differences in readmissions to hospitals with adverse cardiac events, heart failure or major bleeding.[[1,2]] However, regardless of the type of hospital at presentation, Māori have higher mortality following STEMI and NSTEACS compared to non-Māori, non-Pacific peoples and have reduced access to invasive cardiac investigations.[[9]] These inequities are more pronounced for Māori that live in rural areas.[[9,10]] There are few data on the investigations and treatments provided to patients that present to Aotearoa New Zealand rural hospitals with NSTEACS.
The aim of this study was therefore to determine if there were differences in the inpatient investigations and treatments that patients received during an admission with NSTEACS associated with the category of hospital (rural, urban non-interventional or urban interventional) that the patient presented to, and to explore any interactions with ethnicity.
Methods
All first admissions to Aotearoa New Zealand public hospitals for patients aged 20 or older with NSTEACS entered in the All New Zealand Acute Coronary Syndrome Quality Improvement (ANZACS-QI) programme between 1 January 2014 and 31 December 2019 were included in the study.
The ANZACS-QI ACS-CathPCI registry was used, which captures in-depth data on the subset of patients that have acute coronary syndrome (ACS) and receive a coronary angiogram in Aotearoa New Zealand public hospitals (approximately 60% of patients with NSTEACS).[[1,2,11,12]]
Hospitals were identified using the facility code assigned by the New Zealand Ministry of Health and divided into three urban–rural hospital categories (Table 1):[[1,2]]
1. Urban hospitals with routine access to PCI (urban interventional)
2. Urban hospitals without routine access to PCI (urban non-interventional), or
3. Rural hospitals
Patients were assigned to the first hospital of presentation. To account for the movement of patients between hospitals, admission events were bundled together.[[12]]
View Tables 1–4, Figures 1–3.
Clinical performance measures
Clinical performance measures that were considered included: invasive coronary angiography performed within 3 days of first presentation; an assessment of the left ventricular ejection fraction (LVEF); and whether the following medications were prescribed at discharge—aspirin, dual antiplatelet therapy (DAPT), statin, angiotensin-converting enzyme inhibitor or angiotensin receptor blocker (ACEi/ARB) and beta-blockers. These were selected as key indicators of quality care and are consistent with Aotearoa New Zealand ACS targets, as well as Australasian and international guidelines and existing literature.[[6–8]]
Data collected
Age, sex, prioritised ethnicity categorised as Māori, Pacific and non-Māori, non-Pacific peoples (using the Ministry of Health’s protocols),[[13]] body mass index (BMI), smoking status, history of diabetes, congestive heart failure (CHF), prior cardiovascular disease, renal dialysis, admission heart rate (HR) and systolic blood pressure (SBP), low density lipoprotein cholesterol concentration (LDL), initial Killip group,[[14]] cardiac arrest on arrival, estimated glomerular filtration rate (eGFR), Grace score[[15]] and anticoagulant use were collected.
Clinical information included: the time from arrival at the hospital of presentation to angiography (in days); assessment of the LVEF, either by echocardiogram or left ventricular angiogram; findings from angiogram and LVEF assessment; whether PCI was performed; and if there was a referral for (inpatient or outpatient) coronary artery bypass grafting.
The prescription of, or documented contra-indication, to aspirin, another antiplatelet agent, statin, angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB) or beta-blockers were recorded. Patients were considered to have been prescribed dual antiplatelet therapy if they had both aspirin and a second antiplatelet agent prescribed at discharge.
Statistical analysis
Data were summarised using mean and standard deviation (SD) for continuous data and frequency and percentage for categorical data, overall and by hospital category.
Logistic regression, separately for each performance measure, was used to estimate the odds ratios (OR) with 95% confidence intervals (95% CI) comparing urban non-interventional and rural hospitals with urban interventional hospitals (reference group). A binary outcome was created for the prescription of a medication where “prescribed” or “contra-indication” were re-categorised as “true”.
For all models, the following potential confounders of hospital category were included: sex, ethnicity, age, type of NSTEACS, current smoker, prior cardiovascular event, history of diabetes, BMI, HR, SBP, Killip group, LDL, eGFR, history of CHF, health region (Northern, Te Manawa Taki, Central, Southern) and anticoagulant use. LVEF assessment and the findings from this assessment were both considered additional confounders in the models for angiography that occurred within 3 days and prescription of secondary preventative medications. Angiography within 3 days was considered a confounder in the models for LVEF assessment and the prescription of secondary prevention medications.
All model assumptions were checked. Complex non-linear associations were dealt with by categorisation as follows: age (20–44 years, 45–59 years, 60–69 years, 70–89 years and 90+ years); BMI (<18, 18.5–24.9, 25–29.9, 30–34.9 and 35+), heart rate (<50, 50–99, 100–149 and >150 beats per minute); SBP ( <100, 100–149, 150–200 and 201+ mmHg) and LDL (0–1.9, 2–3.9, 4–5.9 and 6+ mmol/L).
Backwards elimination was used to identify and remove non-significant confounders; however, important confounders (age, ethnicity) were retained regardless of significance. Likelihood ratio tests were used to assess the significance of each variable in the model. Only a priori interactions (age and ethnicity) were investigated.
Large amounts (>10%) of missing data within a single variable were categorised and coded as a separate category and included in the regression models. A sensitivity analysis was performed comparing this method with multiple imputation (Appendix 4).
All analyses were performed in R (version 4.1.1) using R-Studio (22.02.3 Boston, MA).[[16]]
Ethics
The ANZACS-QI study is part of a programme of research originally approved by the Northern Region Ethics Committee in 2003 (AKY/03/12/314), with subsequent approval by the National Multi Region Ethics Committee in 2007 (MEC07/19/EXP) and with annual re-approval since as part of a vascular research programme (2022 EXP 13442). Individual patient consent was not required as all data are de-identified.[[11]]
Results
There were 26,779 patients with NSTEACS between 2014 and 2019. Patient characteristics are presented in Table 2. Most patients (66.2%) presented to urban interventional hospitals, with a quarter of patients presenting to urban non-interventional (25.6%) and 8.2% to rural hospitals. A lower percentage of patients that presented to urban interventional hospitals were Māori, compared to urban non-interventional and rural hospitals (8.1%, 17.0% and 13.0% respectively); however, the reverse occurred for Pacific peoples (7.1%, 1.4% and 1.7%). Compared with interventional hospitals, patients that presented to non-interventional and rural hospitals were also more likely to be older (mean age: 65.6 years, 66.4 years and 67 years respectively) and female (30.4%, 34.8% and 33%).
Findings (including ORs) for the process measures angiography within 3 days and assessment of LVEF are shown in Table 3 and Figure 1. There was a significant (p<0.001) interaction between ethnicity and category of hospital for both these two outcome measures.
Invasive coronary angiography within 3 days
Overall, 72.7% of patients received angiography within 3 days; of this, a higher percentage were patients that presented to urban interventional hospitals (78.5%) than rural (60.8%) and urban non-interventional hospitals (63.8%).
For patients presenting to urban interventional hospitals, a lower percentage of Māori (74.3%, OR: 0.78, 95% CI: 0.68 to 0.89) and Pacific peoples (69.3%, OR: 0.75, 95% CI: 0.65 to 0.86) received this investigation compared with non-Māori, non-Pacific peoples (79.8%). For all patients that presented to rural or urban non-interventional hospitals, fewer patients received angiography within 3 days.
Figure 2 shows the time to angiography for each ethnicity and hospital of presentation category.
Assessment of LVEF
Overall, 74.1% of patients received an assessment of LVEF. This percentage was higher for urban interventional (78.5%) compared with rural (66.6%) and urban non-interventional hospitals (65.4%).
A higher percentage of Māori (82.7%, OR: 1.30, 95% CI: 1.12 to 1.51) and Pacific (85.5%, OR: 1.35, 95% CI: 1.14 to 1.62) patients that presented to urban interventional hospitals received an assessment of LVEF compared with non-Māori, non-Pacific peoples (77.5%). However, fewer Māori who presented to urban non-interventional hospitals (68.8%, OR: 0.61, 95% CI: 0.53 to 0.71) and rural hospitals (63.2%, OR: 0.40, 95% CI: 0.31 to 0.52) received this investigation. Similarly, compared to non-Māori, non-Pacific peoples presenting to urban interventional hospitals, fewer non-Māori, non-Pacific peoples who presented to rural hospitals (66.6%, OR: 0.56, 95% CI: 0.50 to 0.62) or urban non-interventional hospitals (64.7%, OR: 0.54, 95% CI: 0.50 to 0.58) received an assessment of the LVEF.
The measured LVEF and the angiography findings were similar across the three categories of hospital and are shown in Appendix 1.
Prescription of secondary prevention medications
Figure 3 and Table 4 present the number, percentage and the unadjusted and adjusted ORs for the prescription of secondary prevention medications at discharge. There were no interactions identified.
Most patients received secondary prevention medications. Nearly all patients had a prescription for aspirin (96.1%), with slightly fewer patients who presented to rural hospitals (95.5%, OR: 0.66, 95% CI: 0.52 to 0.85) or urban non-interventional hospitals (95.1%, OR: 0.89, 95% CI: 0.75 to 1.05) receiving this prescription. A higher percentage of patients that presented to rural hospitals or urban non-interventional hospitals were prescribed beta-blockers (88.3%, OR: 1.34, 95% CI: 1.16 to 1.54 and 86.3%, OR: 1.40, 95% CI: 1.28 to 1.53 respectively) compared with urban interventional hospitals (84.3%).
Adjusting for hospital category of presentation, with the exception of ACEi/ARB (Māori 74.3%, Pacific 78.9%, non-Māori non-Pacific 71.0%), there were no clinically significant differences in the percentage of patients that received a prescription of secondary preventative medication between the three ethnic groups (Appendix 2 and 3).
There were large amounts of missing data (23.5%) for the BMI variable. There were no major differences in the interpretation in any of the outcomes after substituting missing values using multiple imputation (Appendix 4).
Discussion
This national study using the ANZACS-QI registry shows that fewer patients (61% and 63%) who presented to rural hospitals or urban non-interventional hospitals had angiography within 3 days of presentation (and therefore the opportunity for intervention) compared with patients who presented to urban interventional hospitals (78.5%). Only patients presenting to urban interventional hospitals met the Aotearoa New Zealand target of 70%.[[8]] In urban interventional hospitals, Māori and Pacific patients were less likely to receive this investigation within 3 days than non-Māori, non-Pacific patients.
A higher percentage of Māori and Pacific patients that presented to urban interventional hospitals received an assessment of the LVEF compared with non-Māori, non-Pacific patients. However, regardless of ethnicity, patients that presented to rural hospitals or urban non-interventional hospitals were less likely to receive this investigation. The Aotearoa New Zealand target (85%) was only met for Pacific peoples presenting to urban interventional hospitals. Overall, the rates of prescribing for secondary prevention medication at discharge were high.
Invasive coronary angiography
That patients presenting with NSTEACS to rural hospitals or urban non-interventional hospitals waited longer to receive angiography is consistent with Aotearoa New Zealand data in patients diagnosed with STEMI.[[1]] Other Aotearoa New Zealand studies show a similar trend, where patients that presented with NSTEACS in district health boards (DHBs) without PCI capabilities were also less likely to have angiography within 3 days.[[17]] These studies did not differentiate rural from urban hospitals and some DHBs will have included hospitals with and without interventional facilities (e.g., Southern).
Inequities in providing timely angiography for Māori and other Indigenous peoples are well documented.[[9,18]] Our study shows that, regardless of where they present, Māori with NSTEACS wait longer for angiography compared to non-Māori, non-Pacific patients. This disadvantage is worsened for Māori and Pacific peoples who live in urban non-interventional and rural catchments. One potential explanation is the historical lack of angiographic capacity in hospitals that serve large Māori and Pacific populations. We might anticipate this situation could improve with the recent addition of cardiac catheter laboratories to both Whangārei and Middlemore hospitals.[[19]] It is also likely that institutional racism and biases at multiple levels contribute to the inequities for Māori and Pacific peoples seen in our study.[[2,9,20]]
Assessment of LVEF
Access to echocardiography varies throughout Aotearoa New Zealand. Hospitals that do not have cardiothoracic services are less likely to offer this investigation.[[21–23]] Our study shows that patients from urban non-interventional or rural catchments are significantly less likely to have LVEF assessment during their admission, even though all patients were transferred to an interventional centre. This is likely due to a service focus on delivering angiography and maintaining rapid patient throughput in these interventional centres, with patients waiting in rural and urban non-interventional hospitals where access to echocardiography is limited. This finding of fewer patients receiving LVEF assessment in non-interventional hospitals has been previously seen in Australian and Aotearoa New Zealand data.[[24]] The percentage of patients that presented to these non-interventional hospitals in Aotearoa New Zealand and received an LVEF assessment lags behind many other countries and regions (e.g., Israel 72–87.9%, Europe 78–93%, China 81%).[[25,26]]
A higher percentage of Māori and Pacific patients who presented to urban interventional hospitals received an assessment of LVEF compared with non-Māori, non-Pacific peoples; however, this was not apparent for Māori who presented to rural hospitals or urban non-interventional hospitals. This is the opposite situation to coronary angiography. The discrepancy could be explained by the presence of well-developed echocardiographic services but the lack of angiography capacity in hospital catchments with large Māori and Pacific populations. Māori patients are also more likely to present with NSTEACS complicated by cardiac arrest or heart failure. In this situation, echocardiography (but not angiography) is prioritised.[[20]] Where echocardiography is less available, this prioritisation is not possible.
Secondary prevention medication
Regardless of the type of hospital patients presented to, the majority received discharge prescriptions for guideline-directed secondary preventative medications.
While the high overall rate of prescription of these medications is consistent with other Aotearoa New Zealand studies,[[27,28]] our results are in contrast to international data that shows patients from smaller regional and rural places who have NSTEACS were less likely to receive guideline-directed medications.[[24]] The lack of meaningful difference in prescribing at the point of discharge between hospital categories doesn’t explain the small increase in 2-year mortality seen in a previous study,[[2]] although long-term maintenance of these medications for patients who live in rural areas requires further examination.
Patients were more likely to get a prescription for beta-blockers if they presented to rural hospitals or urban non-interventional hospitals. International guidelines acknowledge the role of beta-blockers after NSTEACS in patients with reduced ejection fraction,[[6]] but the role of beta-blockers is uncertain in patients with preserved ejection fraction.[[29]] This uncertainty may be reflected in the prescribing of specialist cardiologists but not of more generalist doctors, who are also less likely to know the patient’s LVEF due to the unavailability of echocardiography. In those that did get echocardiography, there were no differences in the measured LVEF between hospital groups.
Strengths and weaknesses
The strength of this study is the use of the ANZACS-QI Cath-PCI registry. This has a high level of capture of patients that receive angiography.[[12]] A potential limitation is that any investigations (e.g., echocardiography) or treatments (including secondary prevention medications) that patients who didn’t receive angiography (approximately 40% of patients with NSTEACS) may have accessed were not able to be included in the analysis.[[2,17]] Additionally, patients were not risk stratified to determine when angiography should occur according to guidelines (e.g., high-risk patients should have angiography within 24 hours).[[6]] This could be reviewed in future studies. A composite medication outcome wasn’t used for this study and so no comparison could be made with the Aotearoa New Zealand target of 85% for this outcome measure.
This study focusses on which type of hospitals patients present to, rather than the rural–urban category of their usual residence. Future studies using the Geographic Classification for Health are planned.[[3]]
Only investigations and treatments performed during the index admission were considered and it is unknown whether patients had investigations after discharge. Additionally, some patients may have been assessed using non-invasive means, such as CT coronary angiogram.[[12]]
Policy implications
For patients who present to rural hospitals or urban non-interventional hospitals, especially those who are Māori or Pacific, there are ongoing inequities in the timing of angiography and the assessment of LVEF. However, despite these inequities, the category of hospital that a patient presented to didn’t impact mortality or major adverse cardiac events up to 1 year post-NSTEACS.[[2]] This lack of difference in outcomes might reflect the high prescription rates of secondary medications observed in all three categories of hospital.
The success of quality improvement programmes such as ANZACS-QI is well documented, and ongoing reporting of guideline-driven performance measures should consider differentiation of rural and urban areas and include analyses by ethnicity. These differences are often larger than the differences between regions.[[2,30]]
Addressing the mechanisms that facilitate timely (but not necessarily immediate) inter-hospital transfer for investigations in patients with NSTEACS should be a priority for Te Whatu Ora – Health New Zealand and Te Aka Whai Ora – Māori Health Authority to ensure that evidence-based investigations and interventions are performed. In particular, clinicians in urban hospitals with ready access to echocardiography should ensure that this is performed before the patient is discharged back to a provincial or rural location, where this investigation might be harder to access. A robust national registry for echocardiography is also required.
Conclusion
Patients who present to rural hospitals or urban non-interventional hospitals are less likely to receive angiography within 3 days or an assessment of LVEF. Fewer Māori received angiography within 3 days regardless of the category of hospital presentation. There are high levels of the prescribing of secondary prevention medications across all three hospital categories.
View Appendices.
Summary
Abstract
Aim
Compare the care patients with non-ST segment elevation acute coronary syndrome (NSTEACS) received in Aotearoa New Zealand depending on the rural–urban category of the hospital they are first admitted to.
Method
Patients with NSTEACS investigated with invasive coronary angiogram between 1 January 2014 and 31 December 2019 were included. There were three hospital categories (routine access to percutaneous coronary intervention [urban interventional], other urban [urban non-interventional] and rural) and three ethnicity categories (Māori, Pacific and non-Māori/non-Pacific). Clinical performance measures included: angiography ≤3 days, assessment of left ventricular ejection fraction (LVEF) and prescription of secondary prevention medication.
Results
Of 26,779 patients, 66.2% presented to urban-interventional, 25.6% to urban non-interventional and 8.2% to rural hospitals. A smaller percentage of patients presenting to urban interventional than urban non-interventional and rural hospitals were Māori (8.1%, 17.0% and 13.0%). Patients presenting to urban interventional hospitals were more likely to receive timely angiography than urban non-interventional or rural hospitals (78.5%, 60.8% and 63.1%). They were also more likely to have a LVEF assessment (78.5%, 65.4% and 66.3%). In contrast, the use of secondary prevention medications at discharge was similar between hospital categories.
Māori and Pacific patients presenting to urban interventional hospitals were less likely than non-Māori/non-Pacific to receive timely angiography but more likely to have LVEF assessed. However, LVEF assessment and timely angiography in urban non-interventional and rural hospitals were lower than in urban interventional hospitals for both Māori and non-Māori/non-Pacific.
Conclusion
Patients presenting to urban hospitals without routine interventional access and rural hospitals were less likely to receive LVEF assessment or timely angiography. This disproportionately impacts Māori, who are more likely to live in these hospital catchments.
Author Information
Acknowledgements
Correspondence
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Competing Interests
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Investigation and treatment after non-ST segment elevation acute coronary syndrome for patients presenting to rural or urban hospitals in Aotearoa New Zealand: ANZACS-QI 75
In Aotearoa New Zealand, patients with non ST-segment elevation acute coronary syndrome (NSTEACS) may present to one of three main groups of hospitals: urban hospitals i) with (interventional) or ii) without (non-interventional) routine access to percutaneous intervention (PCI), or iii) rural hospitals.
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