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Acute stroke care has transformed in recent years, from a largely supportive-management approach to one that aggressively aims to re-establish blood flow to salvageable brain tissue. Treatment options include intravenous thrombolysis (IVT), stroke clot retrieval (SCR) or both. Stroke reperfusion rates in New Zealand are rising. In 2019, 9.4% of patients were treated with IVT, an increase from 6.5% in 2015, with no overall difference between those in regional and metropolitan areas. Increasing numbers of New Zealanders with acute stroke also have access to SCR, with 342 procedures performed in 2019 (4% of all ischaemic stroke patients) compared to 134 (1.4%) in 2017.[[1]] The percentage of patients with ischaemic stroke who are suitable for SCR is estimated to be around 10%.[[2]] In 2019, there were 8,555 patients admitted to hospital with an ischaemic stroke, indicating that significant work is required to bridge this gap. Currently, SCR is only performed in Auckland City Hospital (ACH), Wellington Regional Hospital (WRH) and Christchurch Hospital. For patients residing outside the geographical catchment area of these centres, there are barriers to accessing treatment. In 2019, metropolitan patients had an SCR rate of 4.2% compared to 1.2% in regional areas. Transfer of stroke patients from regional centres to an SCR centre is feasible and we have previously described a patient transferred from Taranaki to ACH.[[3]] Access barriers include inadequate hyperacute stroke assessment, processes, transport logistics and time constraints.

The aim of this study is to determine whether functional outcomes following SCR for anterior circulation large vessel occlusion (LVO) are equivalent in patients transferred from regional centres (Taranaki) to those in metropolitan (Waitematā and Counties Manakau) centres.

Taranaki District Health Board (DHB) has a catchment population of 120,000 and is located 360kms from ACH by road and 252kms by air, with a flight time of 72 minutes. Waitematā DHB has a catchment population of 628,770. It has two hospitals with road distances of 13kms and 18kms to ACH. Counties Manukau DHB has a catchment population of 578,650. The hospital is 20kms to ACH by road. Key aspects of the Helsinki Thrombolysis Model have been successfully adapted to the New Zealand environment[[4]] and were localised to the Taranaki system; this has been described previously.[[3]] “Code Stroke” activations have been utilised since August 2017 and occur via an internal 777 call to the telephonist. During working hours, the stroke team is comprised of an emergency department physician and nurse, medical registrar, medical house surgeon, duty nurse manager, computer tomography (CT) technician, hospital orderly and stroke clinical nurse specialist and stroke physician. After-hours stroke specialist support was via telephone from ACH until December 2018, at which point telestroke support from WRH was implemented. All patients presenting with acute stroke clinical syndrome routinely have a non-contrast computed topography (NCCT) brain and CT angiography (CTA) from the aortic arch to the brain vertex. CT perfusion (CTP) has been available from January 2020. CT, CTA and CTP is the default imaging setting and can be de-escalated when not required. NCCT thins (bone series and sagittal reformats excluded) and CTA 2mm thins (axial) are automatically uploaded to the Picture Archiving and Communication System (PACS) server for ACH and WRH to review. Rapid transfer of images is achieved using a standalone server and by streamlining firewall rules.

A working group involving all stakeholders was established in late 2017 to initiate protocols, pathways and training. Training included biannual, inter-sector stroke simulations for hospital, helicopter and ambulance personnel. Regular, ongoing education sessions have been held for rotating staff and have assisted to embed the stroke pathway that is now seen as a standard of care.

Methods

Consecutive patients treated with SCR at ACH who were transferred from Taranaki, Waitematā or Counties Manukau DHBs between November 2017 and December 2020 were identified from the New Zealand National Reperfusion Registry and included for analysis. Since late 2018, after-hours presentations of LVO patients from Waitematā and Counties Manukau DHBs have been transferred directly to ACH. These patients were not included in the analysis.

The following baseline characteristics were captured: age, sex, ethnicity, co-morbidities, National Institutes of Health Stroke Scale (NIHSS) score and Alberta Stroke Program Early CT Score (ASPECTS). Stroke onset was defined as the time the patient was last known normal (LKN). Time points of LKN, hospital admission (“to door”), CT, IVT, arrival at the SCR centre and groin puncture time were collected. Successful recanalisation was defined as a modified Thrombolysis in Cerebral Infarction (mTICI) score of 2b to 3. mRS scores were determined at three months.

The primary outcome was the proportion of patients achieving functional independence, defined as an mRS score of 0 to 2 at three months. mRSs were collected centrally by telephone or physical follow-up at three months. Secondary outcomes included early neurological recovery (defined as a reduction in the NIHSS score of ≥8 points from baseline in 24 hours or an NIHSS score of 0 or 1 at 24 hours), ordinal shift of mRS scores at three months, symptomatic intracranial haemorrhage,[[4]] seven-day mortality and three-month mortality. New Zealand’s Health and Disability Ethics Committee approved use of registry data (HDEC 19STH/55).

Statistical analysis was performed using IBM SPSS Statistics, version 26.0 (New York, USA). Results are reported as mean ± standard deviation (SD) or median and interquartile range (IQR). Univariate inter-group comparisons of normally distributed continuous measures were conducted using the independent samples t test, following confirmation with Shapiro-Wilk testing (P>0.05). Non-normally distributed continuous and ordinal data were compared using the Mann-Whitney U test. Categorical data were analysed using Fisher’s exact test. Propensity-score-adjusted logistic or ordinal regression was performed to assess whether there were significant differences in outcome measures between DHB cohorts, with propensity scores being constructed using logit modelling incorporating relevant confounding variables and with a univariate association threshold of P<0.15. All tests were two-tailed, and P<0.05 was considered statistically significant.

Results

There were 274 patients (150 men; mean±age 68.5±14.9 years, median (IQR) baseline NIHSS score of 16 (11–20)) included in the analysis (Table 1). Thirty patients (10.9%) were transferred from Taranaki Base Hospital (TBH)to ACH by helicopter. Two hundred and forty-four patients (89.1%) were transferred from Waitematā and Counties Manukau DHBs by road. Patients from Taranaki were older (74.1 years vs 67.8 years, P=0.03), had lower rates of smoking (10.0% vs 35.7%, P=0.004) and were less ethnically diverse, with a higher proportion of Europeans (86.7% vs 60.7%, P=0.005) and no Pacific or Asian patients. No baseline differences were observed for sex, baseline NIHSS score, ASPECTS or these co-morbidities: atrial fibrillation, congestive heart failure, diabetes, dyslipidaemia, hypertension, ischaemic heart disease and previous stroke.

Table 1: Baseline, transfer, procedural and outcome parameters. View Table 1.

Door-to-CT time was shorter for Taranaki than Waitematā or Counties Manukau (15 minutes vs 21 minutes, P=0.001). There was no difference in IVT treatment rates, door-to-needle times or successful recanalisation rates between Taranaki and the two metropolitan DHBs. Transfers from Taranaki had longer door-to-arrival (at ACH) times (190 minutes vs 120 minutes, P<0.001) and door-to-groin-puncture times (217 minutes vs 140 minutes, P<0.001), compared to transfers from the two metropolitan centres. Propensity-score-adjusted logistic regression odds ratios of outcomes are highlighted in Table 2. There were no differences in outcome measures.

Table 2: Propensity-score-adjusted logistic regression odds ratios of outcome measures by district health board (DHB).

Abbreviations: ASPECTS = Alberta Stroke Program Early CT Score; CI = confidence interval; DHB = District Health Board; IV = intravenous; LKN = last known normal; mRS = modified Rankin Score; NIHSS = National Institutes of Health Stroke Scale; OR = odds ratio.Propensity-score adjusted logistic regression odds ratios and P values are presented. Confounding variables incorporated in propensity score construction using logit modelling, with P <0.15 univariate association threshold:[[1]] Hypertension, baseline NIHSS, baseline ASPECTS, IV thrombolysis, mTICI 2b–3 recanalisation.[[2]] Age, previous stroke, baseline NIHSS, mTICI 2b–3 recanalisation.[[3]] Age, hypertension, coronary artery disease, previous stroke, baseline NIHSS, baseline APSECTS, occlusion site, IV thrombolysis, mTICI 2b–3 recanalisation.[[4]] Age, hypertension, coronary artery disease, previous stroke, baseline NIHSS, baseline APSECTS, occlusion site, IV thrombolysis, mTICI 2b–3 recanalisation.[[5]] Age, male sex, previous stroke, baseline NIHSS, mTICI 2b–3 recanalisation.

Discussion

This study has shown that, despite experiencing a 70-minute delay in the time from LKN to arrival at the SCR centre, patients transferred by helicopter from a regional centre do as well as those transferred by ambulance from metropolitan centres. Our study confirms that this highly effective intervention can be accessed by those in regional areas, provided that appropriate systems and processes are in place. The HERMES metanalysis of SCR trials[[6]] shows a declining benefit from intervention, with increasing time from onset of stroke. However, the majority of Taranaki patients were still treated within the recommended time window of six hours from onset of symptoms.

The hyperacute stroke system at Taranaki results in seamless patient transfer between pre-hospital, hospital and transfer teams. Patients remain on the stroke reperfusion pathway until there is a clear contraindication. Patients suspected of having or identified with an LVO are prepared for transport and transferred to the helicopter prior to acceptance by the SCR centre, which has also been proposed by Ng et al.[[7]] Mobile-phone technology is used to communicate with the helicopter/transfer team who are based on the hospital site.

There continues to be room to further optimise patient workflow. The median door-to-SCR-centre time for Taranaki patients was three hours and 10 minutes, with the shortest time of two hours and 10 minutes. Work from Ng et al[[7]] shows the longest component of CT-to-groin time was CT-to-retrieval request and includes a breakdown of tasks:

  • Imaging acquisition, reconstruction and interpretation
  • Acute treatment decision-making
  • Imaging transfer to SCR centre
  • SCR centre referral
  • Transfer retrieval requests

These tasks should be performed in parallel and not sequentially. Optimised inter-hospital image transfer, use of artificial intelligence in LVO detection and communication tools between teams and simulation training are other areas where workflow can be optimised. Door-to-SCR-centre times should be monitored and considered as an important performance metric by stroke networks.

The main strength of this study is that it has been implemented in a regional hospital with real-world resources and acute stroke care managed by general hospital personnel with specialist stroke support. Also, the complete datasets drawn from nationwide registry data strengthen this study. A number of methodological limitations need to be considered when interpreting the findings of this study. The observational nature precludes the inference of causality. It is possible that unmeasured and residual confounding might have contributed to the results. The small number of patients from a single regional centre limits the generalisability of the findings. Outcome assessors collected the three-month mRS scores as part of the ongoing collection of national SCR registry data for the Ministry of Health, and therefore they were not blinded to treatment. We recommend further analysing all regional transfers. Other outcome proxies, such as hospital length of stay and discharge destination, were not available but should also be considered as key performance indicators.

The Ministry of Health initiated the New Zealand Strategy for Endovascular Clot Retrieval with the goal of achieving geographic and ethnic equity. Successful implementation will require sufficient resources and optimisation of patient care processes to achieve optimal outcomes. Integrated inter-sector and inter-regional systems of stroke care are necessary.

Conclusion

This study has shown that overcoming the post-code lottery for hyperacute stroke care can be achieved in a New Zealand setting. With appropriate hyperacute systems and processes, stroke patients with an LVO from a regional centre can achieve the same outcomes as metropolitan patients.

Summary

Abstract

Aim

Stroke clot retrieval (SCR) is now considered a standard of care for select stroke patients with proximal large vessel occlusion (LVO) of the anterior circulation. Here we present the experience of regional Taranaki patients transferred by air for SCR and compare this to metropolitan Auckland patients who were transferred by road. The aim is to present and compare process metrics and outcomes between the regional and metropolitan centres.

Method

This is a retrospective analysis of consecutive patients with anterior LVO transferred to Auckland City Hospital (ACH) for SCR from Taranaki, Waitematā and Counties Manukau district health boards (DHBs) between November 2017 and December 2020.

Results

Thirty Taranaki patients were transferred for SCR, compared to 244 patients from Waitematā and Counties Manukau DHBs. Taranaki patients were seven years older and less ethnically diverse but similar in other characteristics. The proportion of patients with an independent Modified Rankin Scale (mRS) score between 0 and 2 at three months was the same as for the regional and metropolitan centres.

Conclusion

In this real-world study, regional stroke patients can achieve similar SCR outcomes to metropolitan patients. Overcoming the post-code lottery for hyperacute stroke care can be achieved in a New Zealand setting.

Author Information

Bhavesh Dayal Lallu: Stroke Physician/Geriatrician, Taranaki District Health Board. Jae Beom Hong: Stroke Fellow for the Neurological Foundation of New Zealand and University of Auckland. Michael Wang: Neuro-ophthalmology Research Fellow, Auckland District Health Board and University of Auckland. John Chalissery: Stroke Clinical Nurse Specialist, Taranaki District Health Board. Roger Blume: Intensive Care Paramedic, St John, New Plymouth. Jeanette Langridge: Intensive Care Paramedic, St John, New Plymouth. Sarah Davidson: Lead CT Radiographer, Taranaki District Health Board. Heather Webb: Emergency Physician, Taranaki District Health Board. P Alan Barber: Professor of Neurology, University of Auckland.

Acknowledgements

The authors would like to acknowledge staff at Taranaki District Health Board, St John, Search and Rescue Services Limited and the Taranaki Rescue Helicopter Trust.

Correspondence

Bhavesh Dayal Lallu, Stroke Physician/Geriatrician, Taranaki District Health Board

Correspondence Email

bhavesh.lallu@tdhb.org.nz

Competing Interests

P Alan Barber declares grants or contracts from University of Auckland within the past 36 months.

1. Hedlund F, Leighs A, Barber PA, et al. Trends in stroke reperfusion treatment and outcomes in New Zealand. Internal medicine journal. 2020;50(11):1367-72.

2. Vanacker P, Lambrou D, Eskandari A, et al. Eligibility and Predictors for Acute Revascularization Procedures in a Stroke Center. Stroke. 2016;47(7):1844-9.

3. Lallu BD, Brebner AC, Pepperell B, et al. Stroke reperfusion treatment in regional New Zealand. N Z Med J. 2018;131(1484):74-6.

4. Wu TY, Coleman E, Wright SL, et al. Helsinki Stroke Model Is Transferrable with "Real-World" Resources and Reduced Stroke Thrombolysis Delay to 34 min in Christchurch. Front Neurol. 2018;9:290.

5. Hacke W, Kaste M, Bluhmki E, et al. Thrombolysis with alteplase 3 to 4.5 hours after acute ischemic stroke. N Engl J Med. 2008;359(13):1317-29.

6. Goyal M, Menon BK, van Zwam WH, et al. Endovascular thrombectomy after large-vessel ischaemic stroke: a meta-analysis of individual patient data from five randomised trials. Lancet. 2016;387(10029):1723-31.

7. Stroke Clot Retrieval: A National Service Improvement Programme Action Plan | Ministry of Health NZ: https://nsfl.health.govt.nz/.../stroke_clot_retrieval_action_plan.pdf

8. Ng FC, Low E, Andrew E, et al. Deconstruction of Interhospital Transfer Workflow in Large Vessel Occlusion: Real-World Data in the Thrombectomy Era. Stroke. 2017;48(7):1976-9.

For the PDF of this article,
contact nzmj@nzma.org.nz

View Article PDF

Acute stroke care has transformed in recent years, from a largely supportive-management approach to one that aggressively aims to re-establish blood flow to salvageable brain tissue. Treatment options include intravenous thrombolysis (IVT), stroke clot retrieval (SCR) or both. Stroke reperfusion rates in New Zealand are rising. In 2019, 9.4% of patients were treated with IVT, an increase from 6.5% in 2015, with no overall difference between those in regional and metropolitan areas. Increasing numbers of New Zealanders with acute stroke also have access to SCR, with 342 procedures performed in 2019 (4% of all ischaemic stroke patients) compared to 134 (1.4%) in 2017.[[1]] The percentage of patients with ischaemic stroke who are suitable for SCR is estimated to be around 10%.[[2]] In 2019, there were 8,555 patients admitted to hospital with an ischaemic stroke, indicating that significant work is required to bridge this gap. Currently, SCR is only performed in Auckland City Hospital (ACH), Wellington Regional Hospital (WRH) and Christchurch Hospital. For patients residing outside the geographical catchment area of these centres, there are barriers to accessing treatment. In 2019, metropolitan patients had an SCR rate of 4.2% compared to 1.2% in regional areas. Transfer of stroke patients from regional centres to an SCR centre is feasible and we have previously described a patient transferred from Taranaki to ACH.[[3]] Access barriers include inadequate hyperacute stroke assessment, processes, transport logistics and time constraints.

The aim of this study is to determine whether functional outcomes following SCR for anterior circulation large vessel occlusion (LVO) are equivalent in patients transferred from regional centres (Taranaki) to those in metropolitan (Waitematā and Counties Manakau) centres.

Taranaki District Health Board (DHB) has a catchment population of 120,000 and is located 360kms from ACH by road and 252kms by air, with a flight time of 72 minutes. Waitematā DHB has a catchment population of 628,770. It has two hospitals with road distances of 13kms and 18kms to ACH. Counties Manukau DHB has a catchment population of 578,650. The hospital is 20kms to ACH by road. Key aspects of the Helsinki Thrombolysis Model have been successfully adapted to the New Zealand environment[[4]] and were localised to the Taranaki system; this has been described previously.[[3]] “Code Stroke” activations have been utilised since August 2017 and occur via an internal 777 call to the telephonist. During working hours, the stroke team is comprised of an emergency department physician and nurse, medical registrar, medical house surgeon, duty nurse manager, computer tomography (CT) technician, hospital orderly and stroke clinical nurse specialist and stroke physician. After-hours stroke specialist support was via telephone from ACH until December 2018, at which point telestroke support from WRH was implemented. All patients presenting with acute stroke clinical syndrome routinely have a non-contrast computed topography (NCCT) brain and CT angiography (CTA) from the aortic arch to the brain vertex. CT perfusion (CTP) has been available from January 2020. CT, CTA and CTP is the default imaging setting and can be de-escalated when not required. NCCT thins (bone series and sagittal reformats excluded) and CTA 2mm thins (axial) are automatically uploaded to the Picture Archiving and Communication System (PACS) server for ACH and WRH to review. Rapid transfer of images is achieved using a standalone server and by streamlining firewall rules.

A working group involving all stakeholders was established in late 2017 to initiate protocols, pathways and training. Training included biannual, inter-sector stroke simulations for hospital, helicopter and ambulance personnel. Regular, ongoing education sessions have been held for rotating staff and have assisted to embed the stroke pathway that is now seen as a standard of care.

Methods

Consecutive patients treated with SCR at ACH who were transferred from Taranaki, Waitematā or Counties Manukau DHBs between November 2017 and December 2020 were identified from the New Zealand National Reperfusion Registry and included for analysis. Since late 2018, after-hours presentations of LVO patients from Waitematā and Counties Manukau DHBs have been transferred directly to ACH. These patients were not included in the analysis.

The following baseline characteristics were captured: age, sex, ethnicity, co-morbidities, National Institutes of Health Stroke Scale (NIHSS) score and Alberta Stroke Program Early CT Score (ASPECTS). Stroke onset was defined as the time the patient was last known normal (LKN). Time points of LKN, hospital admission (“to door”), CT, IVT, arrival at the SCR centre and groin puncture time were collected. Successful recanalisation was defined as a modified Thrombolysis in Cerebral Infarction (mTICI) score of 2b to 3. mRS scores were determined at three months.

The primary outcome was the proportion of patients achieving functional independence, defined as an mRS score of 0 to 2 at three months. mRSs were collected centrally by telephone or physical follow-up at three months. Secondary outcomes included early neurological recovery (defined as a reduction in the NIHSS score of ≥8 points from baseline in 24 hours or an NIHSS score of 0 or 1 at 24 hours), ordinal shift of mRS scores at three months, symptomatic intracranial haemorrhage,[[4]] seven-day mortality and three-month mortality. New Zealand’s Health and Disability Ethics Committee approved use of registry data (HDEC 19STH/55).

Statistical analysis was performed using IBM SPSS Statistics, version 26.0 (New York, USA). Results are reported as mean ± standard deviation (SD) or median and interquartile range (IQR). Univariate inter-group comparisons of normally distributed continuous measures were conducted using the independent samples t test, following confirmation with Shapiro-Wilk testing (P>0.05). Non-normally distributed continuous and ordinal data were compared using the Mann-Whitney U test. Categorical data were analysed using Fisher’s exact test. Propensity-score-adjusted logistic or ordinal regression was performed to assess whether there were significant differences in outcome measures between DHB cohorts, with propensity scores being constructed using logit modelling incorporating relevant confounding variables and with a univariate association threshold of P<0.15. All tests were two-tailed, and P<0.05 was considered statistically significant.

Results

There were 274 patients (150 men; mean±age 68.5±14.9 years, median (IQR) baseline NIHSS score of 16 (11–20)) included in the analysis (Table 1). Thirty patients (10.9%) were transferred from Taranaki Base Hospital (TBH)to ACH by helicopter. Two hundred and forty-four patients (89.1%) were transferred from Waitematā and Counties Manukau DHBs by road. Patients from Taranaki were older (74.1 years vs 67.8 years, P=0.03), had lower rates of smoking (10.0% vs 35.7%, P=0.004) and were less ethnically diverse, with a higher proportion of Europeans (86.7% vs 60.7%, P=0.005) and no Pacific or Asian patients. No baseline differences were observed for sex, baseline NIHSS score, ASPECTS or these co-morbidities: atrial fibrillation, congestive heart failure, diabetes, dyslipidaemia, hypertension, ischaemic heart disease and previous stroke.

Table 1: Baseline, transfer, procedural and outcome parameters. View Table 1.

Door-to-CT time was shorter for Taranaki than Waitematā or Counties Manukau (15 minutes vs 21 minutes, P=0.001). There was no difference in IVT treatment rates, door-to-needle times or successful recanalisation rates between Taranaki and the two metropolitan DHBs. Transfers from Taranaki had longer door-to-arrival (at ACH) times (190 minutes vs 120 minutes, P<0.001) and door-to-groin-puncture times (217 minutes vs 140 minutes, P<0.001), compared to transfers from the two metropolitan centres. Propensity-score-adjusted logistic regression odds ratios of outcomes are highlighted in Table 2. There were no differences in outcome measures.

Table 2: Propensity-score-adjusted logistic regression odds ratios of outcome measures by district health board (DHB).

Abbreviations: ASPECTS = Alberta Stroke Program Early CT Score; CI = confidence interval; DHB = District Health Board; IV = intravenous; LKN = last known normal; mRS = modified Rankin Score; NIHSS = National Institutes of Health Stroke Scale; OR = odds ratio.Propensity-score adjusted logistic regression odds ratios and P values are presented. Confounding variables incorporated in propensity score construction using logit modelling, with P <0.15 univariate association threshold:[[1]] Hypertension, baseline NIHSS, baseline ASPECTS, IV thrombolysis, mTICI 2b–3 recanalisation.[[2]] Age, previous stroke, baseline NIHSS, mTICI 2b–3 recanalisation.[[3]] Age, hypertension, coronary artery disease, previous stroke, baseline NIHSS, baseline APSECTS, occlusion site, IV thrombolysis, mTICI 2b–3 recanalisation.[[4]] Age, hypertension, coronary artery disease, previous stroke, baseline NIHSS, baseline APSECTS, occlusion site, IV thrombolysis, mTICI 2b–3 recanalisation.[[5]] Age, male sex, previous stroke, baseline NIHSS, mTICI 2b–3 recanalisation.

Discussion

This study has shown that, despite experiencing a 70-minute delay in the time from LKN to arrival at the SCR centre, patients transferred by helicopter from a regional centre do as well as those transferred by ambulance from metropolitan centres. Our study confirms that this highly effective intervention can be accessed by those in regional areas, provided that appropriate systems and processes are in place. The HERMES metanalysis of SCR trials[[6]] shows a declining benefit from intervention, with increasing time from onset of stroke. However, the majority of Taranaki patients were still treated within the recommended time window of six hours from onset of symptoms.

The hyperacute stroke system at Taranaki results in seamless patient transfer between pre-hospital, hospital and transfer teams. Patients remain on the stroke reperfusion pathway until there is a clear contraindication. Patients suspected of having or identified with an LVO are prepared for transport and transferred to the helicopter prior to acceptance by the SCR centre, which has also been proposed by Ng et al.[[7]] Mobile-phone technology is used to communicate with the helicopter/transfer team who are based on the hospital site.

There continues to be room to further optimise patient workflow. The median door-to-SCR-centre time for Taranaki patients was three hours and 10 minutes, with the shortest time of two hours and 10 minutes. Work from Ng et al[[7]] shows the longest component of CT-to-groin time was CT-to-retrieval request and includes a breakdown of tasks:

  • Imaging acquisition, reconstruction and interpretation
  • Acute treatment decision-making
  • Imaging transfer to SCR centre
  • SCR centre referral
  • Transfer retrieval requests

These tasks should be performed in parallel and not sequentially. Optimised inter-hospital image transfer, use of artificial intelligence in LVO detection and communication tools between teams and simulation training are other areas where workflow can be optimised. Door-to-SCR-centre times should be monitored and considered as an important performance metric by stroke networks.

The main strength of this study is that it has been implemented in a regional hospital with real-world resources and acute stroke care managed by general hospital personnel with specialist stroke support. Also, the complete datasets drawn from nationwide registry data strengthen this study. A number of methodological limitations need to be considered when interpreting the findings of this study. The observational nature precludes the inference of causality. It is possible that unmeasured and residual confounding might have contributed to the results. The small number of patients from a single regional centre limits the generalisability of the findings. Outcome assessors collected the three-month mRS scores as part of the ongoing collection of national SCR registry data for the Ministry of Health, and therefore they were not blinded to treatment. We recommend further analysing all regional transfers. Other outcome proxies, such as hospital length of stay and discharge destination, were not available but should also be considered as key performance indicators.

The Ministry of Health initiated the New Zealand Strategy for Endovascular Clot Retrieval with the goal of achieving geographic and ethnic equity. Successful implementation will require sufficient resources and optimisation of patient care processes to achieve optimal outcomes. Integrated inter-sector and inter-regional systems of stroke care are necessary.

Conclusion

This study has shown that overcoming the post-code lottery for hyperacute stroke care can be achieved in a New Zealand setting. With appropriate hyperacute systems and processes, stroke patients with an LVO from a regional centre can achieve the same outcomes as metropolitan patients.

Summary

Abstract

Aim

Stroke clot retrieval (SCR) is now considered a standard of care for select stroke patients with proximal large vessel occlusion (LVO) of the anterior circulation. Here we present the experience of regional Taranaki patients transferred by air for SCR and compare this to metropolitan Auckland patients who were transferred by road. The aim is to present and compare process metrics and outcomes between the regional and metropolitan centres.

Method

This is a retrospective analysis of consecutive patients with anterior LVO transferred to Auckland City Hospital (ACH) for SCR from Taranaki, Waitematā and Counties Manukau district health boards (DHBs) between November 2017 and December 2020.

Results

Thirty Taranaki patients were transferred for SCR, compared to 244 patients from Waitematā and Counties Manukau DHBs. Taranaki patients were seven years older and less ethnically diverse but similar in other characteristics. The proportion of patients with an independent Modified Rankin Scale (mRS) score between 0 and 2 at three months was the same as for the regional and metropolitan centres.

Conclusion

In this real-world study, regional stroke patients can achieve similar SCR outcomes to metropolitan patients. Overcoming the post-code lottery for hyperacute stroke care can be achieved in a New Zealand setting.

Author Information

Bhavesh Dayal Lallu: Stroke Physician/Geriatrician, Taranaki District Health Board. Jae Beom Hong: Stroke Fellow for the Neurological Foundation of New Zealand and University of Auckland. Michael Wang: Neuro-ophthalmology Research Fellow, Auckland District Health Board and University of Auckland. John Chalissery: Stroke Clinical Nurse Specialist, Taranaki District Health Board. Roger Blume: Intensive Care Paramedic, St John, New Plymouth. Jeanette Langridge: Intensive Care Paramedic, St John, New Plymouth. Sarah Davidson: Lead CT Radiographer, Taranaki District Health Board. Heather Webb: Emergency Physician, Taranaki District Health Board. P Alan Barber: Professor of Neurology, University of Auckland.

Acknowledgements

The authors would like to acknowledge staff at Taranaki District Health Board, St John, Search and Rescue Services Limited and the Taranaki Rescue Helicopter Trust.

Correspondence

Bhavesh Dayal Lallu, Stroke Physician/Geriatrician, Taranaki District Health Board

Correspondence Email

bhavesh.lallu@tdhb.org.nz

Competing Interests

P Alan Barber declares grants or contracts from University of Auckland within the past 36 months.

1. Hedlund F, Leighs A, Barber PA, et al. Trends in stroke reperfusion treatment and outcomes in New Zealand. Internal medicine journal. 2020;50(11):1367-72.

2. Vanacker P, Lambrou D, Eskandari A, et al. Eligibility and Predictors for Acute Revascularization Procedures in a Stroke Center. Stroke. 2016;47(7):1844-9.

3. Lallu BD, Brebner AC, Pepperell B, et al. Stroke reperfusion treatment in regional New Zealand. N Z Med J. 2018;131(1484):74-6.

4. Wu TY, Coleman E, Wright SL, et al. Helsinki Stroke Model Is Transferrable with "Real-World" Resources and Reduced Stroke Thrombolysis Delay to 34 min in Christchurch. Front Neurol. 2018;9:290.

5. Hacke W, Kaste M, Bluhmki E, et al. Thrombolysis with alteplase 3 to 4.5 hours after acute ischemic stroke. N Engl J Med. 2008;359(13):1317-29.

6. Goyal M, Menon BK, van Zwam WH, et al. Endovascular thrombectomy after large-vessel ischaemic stroke: a meta-analysis of individual patient data from five randomised trials. Lancet. 2016;387(10029):1723-31.

7. Stroke Clot Retrieval: A National Service Improvement Programme Action Plan | Ministry of Health NZ: https://nsfl.health.govt.nz/.../stroke_clot_retrieval_action_plan.pdf

8. Ng FC, Low E, Andrew E, et al. Deconstruction of Interhospital Transfer Workflow in Large Vessel Occlusion: Real-World Data in the Thrombectomy Era. Stroke. 2017;48(7):1976-9.

For the PDF of this article,
contact nzmj@nzma.org.nz

View Article PDF

Acute stroke care has transformed in recent years, from a largely supportive-management approach to one that aggressively aims to re-establish blood flow to salvageable brain tissue. Treatment options include intravenous thrombolysis (IVT), stroke clot retrieval (SCR) or both. Stroke reperfusion rates in New Zealand are rising. In 2019, 9.4% of patients were treated with IVT, an increase from 6.5% in 2015, with no overall difference between those in regional and metropolitan areas. Increasing numbers of New Zealanders with acute stroke also have access to SCR, with 342 procedures performed in 2019 (4% of all ischaemic stroke patients) compared to 134 (1.4%) in 2017.[[1]] The percentage of patients with ischaemic stroke who are suitable for SCR is estimated to be around 10%.[[2]] In 2019, there were 8,555 patients admitted to hospital with an ischaemic stroke, indicating that significant work is required to bridge this gap. Currently, SCR is only performed in Auckland City Hospital (ACH), Wellington Regional Hospital (WRH) and Christchurch Hospital. For patients residing outside the geographical catchment area of these centres, there are barriers to accessing treatment. In 2019, metropolitan patients had an SCR rate of 4.2% compared to 1.2% in regional areas. Transfer of stroke patients from regional centres to an SCR centre is feasible and we have previously described a patient transferred from Taranaki to ACH.[[3]] Access barriers include inadequate hyperacute stroke assessment, processes, transport logistics and time constraints.

The aim of this study is to determine whether functional outcomes following SCR for anterior circulation large vessel occlusion (LVO) are equivalent in patients transferred from regional centres (Taranaki) to those in metropolitan (Waitematā and Counties Manakau) centres.

Taranaki District Health Board (DHB) has a catchment population of 120,000 and is located 360kms from ACH by road and 252kms by air, with a flight time of 72 minutes. Waitematā DHB has a catchment population of 628,770. It has two hospitals with road distances of 13kms and 18kms to ACH. Counties Manukau DHB has a catchment population of 578,650. The hospital is 20kms to ACH by road. Key aspects of the Helsinki Thrombolysis Model have been successfully adapted to the New Zealand environment[[4]] and were localised to the Taranaki system; this has been described previously.[[3]] “Code Stroke” activations have been utilised since August 2017 and occur via an internal 777 call to the telephonist. During working hours, the stroke team is comprised of an emergency department physician and nurse, medical registrar, medical house surgeon, duty nurse manager, computer tomography (CT) technician, hospital orderly and stroke clinical nurse specialist and stroke physician. After-hours stroke specialist support was via telephone from ACH until December 2018, at which point telestroke support from WRH was implemented. All patients presenting with acute stroke clinical syndrome routinely have a non-contrast computed topography (NCCT) brain and CT angiography (CTA) from the aortic arch to the brain vertex. CT perfusion (CTP) has been available from January 2020. CT, CTA and CTP is the default imaging setting and can be de-escalated when not required. NCCT thins (bone series and sagittal reformats excluded) and CTA 2mm thins (axial) are automatically uploaded to the Picture Archiving and Communication System (PACS) server for ACH and WRH to review. Rapid transfer of images is achieved using a standalone server and by streamlining firewall rules.

A working group involving all stakeholders was established in late 2017 to initiate protocols, pathways and training. Training included biannual, inter-sector stroke simulations for hospital, helicopter and ambulance personnel. Regular, ongoing education sessions have been held for rotating staff and have assisted to embed the stroke pathway that is now seen as a standard of care.

Methods

Consecutive patients treated with SCR at ACH who were transferred from Taranaki, Waitematā or Counties Manukau DHBs between November 2017 and December 2020 were identified from the New Zealand National Reperfusion Registry and included for analysis. Since late 2018, after-hours presentations of LVO patients from Waitematā and Counties Manukau DHBs have been transferred directly to ACH. These patients were not included in the analysis.

The following baseline characteristics were captured: age, sex, ethnicity, co-morbidities, National Institutes of Health Stroke Scale (NIHSS) score and Alberta Stroke Program Early CT Score (ASPECTS). Stroke onset was defined as the time the patient was last known normal (LKN). Time points of LKN, hospital admission (“to door”), CT, IVT, arrival at the SCR centre and groin puncture time were collected. Successful recanalisation was defined as a modified Thrombolysis in Cerebral Infarction (mTICI) score of 2b to 3. mRS scores were determined at three months.

The primary outcome was the proportion of patients achieving functional independence, defined as an mRS score of 0 to 2 at three months. mRSs were collected centrally by telephone or physical follow-up at three months. Secondary outcomes included early neurological recovery (defined as a reduction in the NIHSS score of ≥8 points from baseline in 24 hours or an NIHSS score of 0 or 1 at 24 hours), ordinal shift of mRS scores at three months, symptomatic intracranial haemorrhage,[[4]] seven-day mortality and three-month mortality. New Zealand’s Health and Disability Ethics Committee approved use of registry data (HDEC 19STH/55).

Statistical analysis was performed using IBM SPSS Statistics, version 26.0 (New York, USA). Results are reported as mean ± standard deviation (SD) or median and interquartile range (IQR). Univariate inter-group comparisons of normally distributed continuous measures were conducted using the independent samples t test, following confirmation with Shapiro-Wilk testing (P>0.05). Non-normally distributed continuous and ordinal data were compared using the Mann-Whitney U test. Categorical data were analysed using Fisher’s exact test. Propensity-score-adjusted logistic or ordinal regression was performed to assess whether there were significant differences in outcome measures between DHB cohorts, with propensity scores being constructed using logit modelling incorporating relevant confounding variables and with a univariate association threshold of P<0.15. All tests were two-tailed, and P<0.05 was considered statistically significant.

Results

There were 274 patients (150 men; mean±age 68.5±14.9 years, median (IQR) baseline NIHSS score of 16 (11–20)) included in the analysis (Table 1). Thirty patients (10.9%) were transferred from Taranaki Base Hospital (TBH)to ACH by helicopter. Two hundred and forty-four patients (89.1%) were transferred from Waitematā and Counties Manukau DHBs by road. Patients from Taranaki were older (74.1 years vs 67.8 years, P=0.03), had lower rates of smoking (10.0% vs 35.7%, P=0.004) and were less ethnically diverse, with a higher proportion of Europeans (86.7% vs 60.7%, P=0.005) and no Pacific or Asian patients. No baseline differences were observed for sex, baseline NIHSS score, ASPECTS or these co-morbidities: atrial fibrillation, congestive heart failure, diabetes, dyslipidaemia, hypertension, ischaemic heart disease and previous stroke.

Table 1: Baseline, transfer, procedural and outcome parameters. View Table 1.

Door-to-CT time was shorter for Taranaki than Waitematā or Counties Manukau (15 minutes vs 21 minutes, P=0.001). There was no difference in IVT treatment rates, door-to-needle times or successful recanalisation rates between Taranaki and the two metropolitan DHBs. Transfers from Taranaki had longer door-to-arrival (at ACH) times (190 minutes vs 120 minutes, P<0.001) and door-to-groin-puncture times (217 minutes vs 140 minutes, P<0.001), compared to transfers from the two metropolitan centres. Propensity-score-adjusted logistic regression odds ratios of outcomes are highlighted in Table 2. There were no differences in outcome measures.

Table 2: Propensity-score-adjusted logistic regression odds ratios of outcome measures by district health board (DHB).

Abbreviations: ASPECTS = Alberta Stroke Program Early CT Score; CI = confidence interval; DHB = District Health Board; IV = intravenous; LKN = last known normal; mRS = modified Rankin Score; NIHSS = National Institutes of Health Stroke Scale; OR = odds ratio.Propensity-score adjusted logistic regression odds ratios and P values are presented. Confounding variables incorporated in propensity score construction using logit modelling, with P <0.15 univariate association threshold:[[1]] Hypertension, baseline NIHSS, baseline ASPECTS, IV thrombolysis, mTICI 2b–3 recanalisation.[[2]] Age, previous stroke, baseline NIHSS, mTICI 2b–3 recanalisation.[[3]] Age, hypertension, coronary artery disease, previous stroke, baseline NIHSS, baseline APSECTS, occlusion site, IV thrombolysis, mTICI 2b–3 recanalisation.[[4]] Age, hypertension, coronary artery disease, previous stroke, baseline NIHSS, baseline APSECTS, occlusion site, IV thrombolysis, mTICI 2b–3 recanalisation.[[5]] Age, male sex, previous stroke, baseline NIHSS, mTICI 2b–3 recanalisation.

Discussion

This study has shown that, despite experiencing a 70-minute delay in the time from LKN to arrival at the SCR centre, patients transferred by helicopter from a regional centre do as well as those transferred by ambulance from metropolitan centres. Our study confirms that this highly effective intervention can be accessed by those in regional areas, provided that appropriate systems and processes are in place. The HERMES metanalysis of SCR trials[[6]] shows a declining benefit from intervention, with increasing time from onset of stroke. However, the majority of Taranaki patients were still treated within the recommended time window of six hours from onset of symptoms.

The hyperacute stroke system at Taranaki results in seamless patient transfer between pre-hospital, hospital and transfer teams. Patients remain on the stroke reperfusion pathway until there is a clear contraindication. Patients suspected of having or identified with an LVO are prepared for transport and transferred to the helicopter prior to acceptance by the SCR centre, which has also been proposed by Ng et al.[[7]] Mobile-phone technology is used to communicate with the helicopter/transfer team who are based on the hospital site.

There continues to be room to further optimise patient workflow. The median door-to-SCR-centre time for Taranaki patients was three hours and 10 minutes, with the shortest time of two hours and 10 minutes. Work from Ng et al[[7]] shows the longest component of CT-to-groin time was CT-to-retrieval request and includes a breakdown of tasks:

  • Imaging acquisition, reconstruction and interpretation
  • Acute treatment decision-making
  • Imaging transfer to SCR centre
  • SCR centre referral
  • Transfer retrieval requests

These tasks should be performed in parallel and not sequentially. Optimised inter-hospital image transfer, use of artificial intelligence in LVO detection and communication tools between teams and simulation training are other areas where workflow can be optimised. Door-to-SCR-centre times should be monitored and considered as an important performance metric by stroke networks.

The main strength of this study is that it has been implemented in a regional hospital with real-world resources and acute stroke care managed by general hospital personnel with specialist stroke support. Also, the complete datasets drawn from nationwide registry data strengthen this study. A number of methodological limitations need to be considered when interpreting the findings of this study. The observational nature precludes the inference of causality. It is possible that unmeasured and residual confounding might have contributed to the results. The small number of patients from a single regional centre limits the generalisability of the findings. Outcome assessors collected the three-month mRS scores as part of the ongoing collection of national SCR registry data for the Ministry of Health, and therefore they were not blinded to treatment. We recommend further analysing all regional transfers. Other outcome proxies, such as hospital length of stay and discharge destination, were not available but should also be considered as key performance indicators.

The Ministry of Health initiated the New Zealand Strategy for Endovascular Clot Retrieval with the goal of achieving geographic and ethnic equity. Successful implementation will require sufficient resources and optimisation of patient care processes to achieve optimal outcomes. Integrated inter-sector and inter-regional systems of stroke care are necessary.

Conclusion

This study has shown that overcoming the post-code lottery for hyperacute stroke care can be achieved in a New Zealand setting. With appropriate hyperacute systems and processes, stroke patients with an LVO from a regional centre can achieve the same outcomes as metropolitan patients.

Summary

Abstract

Aim

Stroke clot retrieval (SCR) is now considered a standard of care for select stroke patients with proximal large vessel occlusion (LVO) of the anterior circulation. Here we present the experience of regional Taranaki patients transferred by air for SCR and compare this to metropolitan Auckland patients who were transferred by road. The aim is to present and compare process metrics and outcomes between the regional and metropolitan centres.

Method

This is a retrospective analysis of consecutive patients with anterior LVO transferred to Auckland City Hospital (ACH) for SCR from Taranaki, Waitematā and Counties Manukau district health boards (DHBs) between November 2017 and December 2020.

Results

Thirty Taranaki patients were transferred for SCR, compared to 244 patients from Waitematā and Counties Manukau DHBs. Taranaki patients were seven years older and less ethnically diverse but similar in other characteristics. The proportion of patients with an independent Modified Rankin Scale (mRS) score between 0 and 2 at three months was the same as for the regional and metropolitan centres.

Conclusion

In this real-world study, regional stroke patients can achieve similar SCR outcomes to metropolitan patients. Overcoming the post-code lottery for hyperacute stroke care can be achieved in a New Zealand setting.

Author Information

Bhavesh Dayal Lallu: Stroke Physician/Geriatrician, Taranaki District Health Board. Jae Beom Hong: Stroke Fellow for the Neurological Foundation of New Zealand and University of Auckland. Michael Wang: Neuro-ophthalmology Research Fellow, Auckland District Health Board and University of Auckland. John Chalissery: Stroke Clinical Nurse Specialist, Taranaki District Health Board. Roger Blume: Intensive Care Paramedic, St John, New Plymouth. Jeanette Langridge: Intensive Care Paramedic, St John, New Plymouth. Sarah Davidson: Lead CT Radiographer, Taranaki District Health Board. Heather Webb: Emergency Physician, Taranaki District Health Board. P Alan Barber: Professor of Neurology, University of Auckland.

Acknowledgements

The authors would like to acknowledge staff at Taranaki District Health Board, St John, Search and Rescue Services Limited and the Taranaki Rescue Helicopter Trust.

Correspondence

Bhavesh Dayal Lallu, Stroke Physician/Geriatrician, Taranaki District Health Board

Correspondence Email

bhavesh.lallu@tdhb.org.nz

Competing Interests

P Alan Barber declares grants or contracts from University of Auckland within the past 36 months.

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4. Wu TY, Coleman E, Wright SL, et al. Helsinki Stroke Model Is Transferrable with "Real-World" Resources and Reduced Stroke Thrombolysis Delay to 34 min in Christchurch. Front Neurol. 2018;9:290.

5. Hacke W, Kaste M, Bluhmki E, et al. Thrombolysis with alteplase 3 to 4.5 hours after acute ischemic stroke. N Engl J Med. 2008;359(13):1317-29.

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7. Stroke Clot Retrieval: A National Service Improvement Programme Action Plan | Ministry of Health NZ: https://nsfl.health.govt.nz/.../stroke_clot_retrieval_action_plan.pdf

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