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Abdominal aortic aneurysms (AAA) are a significant cause of mortality in New Zealand accounting for about 236 deaths per year, of which 80% are attributed to ruptures.1 Recent international studies suggest that the prevalence of AAA is about 2% in men aged 65.2,3 The natural history of AAA is a progressive increase in diameter to the point of rupture. The risk of aneurysm rupture increases with increasing diameter.Approximately, 30% of patients with a ruptured AAA die pre-hospital. Of those undergoing repair, the mortality rate is approximately 35%. There is an overall mortality rate of up to 85%.4 However, when detected prior to rupture, they can be treated electively by open or endovascular methods, with open surgical procedures carrying a mortality of 3-10%.5Four randomised controlled trials summarised by a meta-analysis showed that ultrasound AAA screening was associated with a significant reduction of AAA-related mortality in men aged 65-79 years.5 There are six countries that offer screening or are in the process of developing screening programs for AAA.6 Currently, no such programme exists in New Zealand, although consideration has been given to initiating one. Nair and colleagues have documented the burden of AAA in New Zealand from 2002 until 2006.1 An average of 267 AAA were repaired electively, and a further 87 repaired as an emergency each year. Mortality rates for elective and emergency repairs were 6.7% and 35.2% respectively. Almost all AAA deaths occurred in people aged over 65 years.1 Sandiford et al report declining incidence and mortality rates of AAA in New Zealand since 1991, which may be attributable to a reduction in smoking rates and the use of statins to control serum cholesterol.7 In New Zealand, the prevalence of AAA in the population is still unknown, but in a selected population undergoing CT colonography for gastrointestinal symptoms, a prevalence of 9.1 % in men 65-75 years old was observed. 8 This highlights the burden of AAA disease in New Zealand and the importance of an AAA screening program.Cost analysis comparing open aneurysm repair (OAR) and endovascular aneurysm repair (EVAR) has been assessed in randomised controlled trials.9,10 However, inpatient costs of AAA repair in the contemporary clinical setting have not been assessed in New Zealand.11 The aim of this study was to compare the hospital costs of AAA repair in emergency and elective cases over a 3-year period in a tertiary referral vascular centre.MethodsThis was a retrospective, observational analysis of consecutive patients undergoing elective and emergency AAA repair, from 1 January 2009 until 31 December 2011, in a single New Zealand centre.The exclusion criteria was: isolated iliac aneurysms with open or endovascular methods; non-aneurysmal aortic surgery for occlusive disease; complex fenestrated and branched endovascular aneurysm repair (EVAR) grafts; or treatment for infected aortic grafts or mycotic aneurysms.The unit s protocol for all patients undergoing open AAA repair was to stay in ICU for one night minimum. There is no routine ICU or HDU for EVAR patients. The majority of elective cases were admitted into hospital on the same day of surgery and EVAR patients receive their first imaging surveillance (ultrasound) at 6 weeks post-operatively, unless there were any clinical concerns.Patients were identified using a prospectively-collected vascular database and the hospital s decision support tool. Patients clinical presentations were defined into three groups: ruptured AAA repair; symptomatic but not ruptured AAA repair; or elective AAA repair. Information for each patient was extracted from the vascular database, including demographics, vascular risk factors and length of stay (LOS). The hospital s decision clinical coding data was used to extract the cost of each admission. The costing system uses several techniques used to derive each inpatient costs. Inventoried items (eg, theatre materials, grafts, blood products) are recorded for each admission and are assigned a value based on the cost of the product to the DHB. There is a similar process with hospital services (eg, labs, ECHO, radiology). Nursing and doctor s hours are assigned a value based on the time spent in a particular location of for the patient (eg, theatre, ICU, ward) which reflect the differences in staff numbers and salary for each. The time of other health care providers is also logged and includes physiotherapy, social work, phlebotomy, and inpatient specialist referral. The components used to determine the cost of each admission were examined and grouped into the following categories for analysis: pre-hospital (including pre-admission and air ambulance costs), operation, intensive care, blood products, laboratory and other.Four separate analyses were performed: The difference in costs of OAR between elective and ruptured groups was examined. EVAR patients were not included in the primary analysis as it was hypothesised that an unequal distribution of EVAR, with a high stent graft cost, in the elective group would affect the comparability of the groups. In addition, the use of EVAR for treating ruptured AAA has not been widely adopted at our institution. OAR were examined, excluding patients who died in less than 4 days, as it was hypothesised that early mortality would lead to a lower difference of cost between the groups. All patients presentations who had OAR and EVAR were analysed. OAR was compared to EVAR in the elective cases only to provide context for the other analyses and to provide data for future modelling. Analyses were carried out using SAS/STAT 12.1 software. All t-tests used the Satterthwaite approximation for unequal variances. Statistical significance was set at p<0.05. Although cost distributions were inspected and found to be skewed with long tails of high values, analyses focused on mean costs rather than the medians, as these are what are relevant to health care planners.12ResultsA total of 169 AAA were repaired during the study period. This consisted of 117 (69.2%) elective repairs (64 OAR and 53 EVAR), 42 (24.9%) ruptured repairs (40 OAR and 2 EVAR), and 10 (5.9%) symptomatic repairs (all OAR). The total number of ruptured AAA presenting to the hospital during this period was 89, of which 47 (53%) were managed non-operatively, either dying before reaching the operating theatre or after having decided not to undergo operation. Demographics and risk factors for each group is summarised in Table 1. The median age for the elective, ruptured, and symptomatic groups was 73, 77 and 74 years, respectively. All three groups consisted primarily of male patients. The elective group had a higher proportion of patients with ischaemic heart disease, who were receiving statin and antiplatelet therapy compared to the other groups. The symptomatic group had the highest proportion of patients with a recorded history of smoking and hypertension. There was no 30-day mortality in the elective or symptomatic groups. The 30-day mortality of the ruptured aneurysms repaired was 11 out of 42 (26.2%).Table 1: Summary of demographics and risk factors for open AAA repairs. Elective Ruptured Symptomatic n= 64 40 10 Median age (range) 73 (57-86) 77 (49-86) 74 (62-82) Males (%) 46 (72) 34 (85) 8 (80) Diabetes (%) 3 (4) 4 (10) 0 Smoking history (%) 37 (58) 17 (42) 6 (60) Hypertension (%) 34 (53) 18 (45) 7 (70) Ischaemic heart disease (%) 20 (31) 6 (15) 2 (20) On statin therapy (%) 35 (55) 13 (33) 3 (30) On antiplatelet therapy (%) 37 (61) 13 (33) 5 (50) Median ASA\u2020 (range) 3 (2-4) 3 (2-5) 3 (2-3) 30-day mortality (%) 0 11 (28) 0 \u2020American Society of Anesthesiologists physical status classification systemThirteen out of the 117 (11%) elective patients, and 7 out of the 42 (17%) of ruptured patients, were discharged to a rehabilitation facility. The median length of stay (LOS) in rehabilitation for the elective and rupture group was 8 and 12 days respectively.Primary analysis: Costs of open AAA repairs between elective and ruptured groups114 open AAA were repaired during the study period. Of those, 64 were elective repairs, 40 were ruptures and 10 were symptomatic repairs. Figure 1 demonstrates the number of open repairs performed annually stratified by the indication for surgery.Figure 1: The number of open AAA repairs performed in each year of the study period stratified by the indication for surgery. The costs and LOS amongst the groups included in the primary analysis is presented in Table 2. The mean cost per patient in the open elective group was $28,019. In the open ruptured group it was $38,804, and for the open symptomatic group it was $33,743. The distribution of the total cost per group is demonstrated by the box plots in Figure 2. The mean LOS was 9 days for elective, 10 days for rupture, and 12 days for symptomatic admissions. The most significant categories contributing to the total costs amongst the three groups were operation, ward and ICU costs, with overall means of $9,644, $9,343 and $9,009, respectively. The median time from start of anaesthetic until leaving operating theatre for the elective, rupture group and the symptomatic groups was 265, 205 and 224 minutes respectively.Table 2: Costs and length of stay of open AAA repair in the primary analysis. Group Variable Mean (SD) Median (Q1-Q3) Elective (n=64) Length of stay (days) 9 (5) 8 (6-11) Total cost $28,019 (16,306) $24,628 ($21,012-$29,306) Pre-hospital $149 (200) $159 ($0-$198) Operation $9,763 (2,880) $8,413 ($6,568-$9,618) ICU $6,500 (10817) $4,487 ($3,905-$5,113) Blood products $373 (954) $49 ($0-$546) Laboratory costs $402 (337) $327 ($237-$459) Ward costs $9,498 (3988) $9,053 ($7,157-$11,790) Other $1,335 (2053) $666 ($358-$1,225) Ruptured (n=40) Length of stay (days) 10 (8) 9 (4-16) Total cost $38,804 (30,620) $31,895 ($24,691-$40,7301) Pre-hospital $241 (1,497) $0 ($0-$0) \u2020 Operation $9,682 (5,061) $9,115 ($6,960-$11,346) ICU $13,250 (21,693) $7,868 ($3,857-$14,166) Blood products $4,404 (6,069) $2,328 ($1,195-$4,772) Laboratory costs $731 (591) $549 ($422-$884) Ward costs $8,170 (7,431) $7,400 ($610-$13,229) Other $2,327 (3559) $1,248 ($562-$2,298) Symptomatic (n=10) Length of stay (days) 12 (9) 8 (7-15) Total cost $33, 743 (19,351) $25,891 ($21,973-$36,439) Pre- hospital $432 (869) $0 ($0-$179) Operation $8,740 (1,414) $9,083 ($8,315-$9,774) ICU $8,108 (7,079) $4,679 ($3,975-$8,854) Blood products $905 (1,026) $820 ($43-$1,225) Laboratory costs $666 (558) $508 ($306-$764) Ward costs $13,050 (10,378) $7,673 ($6,938-$17,071) Other $1,842 (1,612) $1,344 ($617-$2,013) \u20203 patients Figure 2: Box plots demonstrating the distribution of inpatient costs in each study group. Table 3 shows the statistical comparison between the open rupture and elective groups. There was a significant difference between the mean inpatient cost of open ruptured AAA repair and open elective AAA repair of $10,785 (95%CI: $249, $21,321; p=0.045). The cost of blood products was $4,031 greater (95%CI: $2,077, $5,985; p=0.0002), and the cost of laboratory investigations was $329 greater (95%CI: $123, $534; p=0.002) in the ruptured group than the elective group. There was no difference in pre-hospital, operation, ICU, ward or \u2018other costs between the groups. There was no significant difference in LOS between the two groups.Table 3: Statistical comparison of length of stay and costs between open ruptured and elective groups. Mean cost ruptured (SD) [n=40] Mean cost elective (SD) [n=64] Mean Difference 95% CI for difference Length of stay (days) 10 (8) 9 (5) 1 -2, 4 Total cost $38,804 (30,620) $28,019 (16,306) $10,785* $249, $21,321 Pre- hospital $241 (1,497) $149 (200) $92 -$389, $573 Operation $9,682 (5,061) $9,763 (2,880) -$81 -$1,839, $1,677 ICU $13,250 (21,693) $6,500 (10,817) $6,750 -$650, $14,150 Blood products $4,404 (6,069) $373 (954) $4,031*** $2,077, $5,985 Laboratory costs $731 (591) $402 (337) $329** $123, $534 Ward costs $8,170 (7,431) $9,498 (3,988) -$1,328 -$3,888, $1,231 Other $2,327 (3,559) $1,335 (2,053) $992 -$247, $2,231 *p <0.05, **p <0.01, ***p <0.001Costs of open AAA repairs between elective and ruptured groups, excluding early (<4 day) mortalityOf the 40 patients with ruptured AAA who had a repair, nine died within four days. The mean difference of costs between ruptured and elective groups with early mortality excluded is presented in Table 4. In this analysis, there was a significant mean difference of $16,163 (95%CI: $3,612, $28,714; p=0.01) between open ruptured AAA repair and open elective AAA repair. ICU, blood product, laboratory and \u2018other costs were significantly higher in the ruptured group, while pre-hospital, operation and ward costs were not different.Table 4: Statistical comparison of length of stay and costs between open rupture and elective groups with early mortality (<4 days) excluded. Mean cost ruptured (SD) [n=31] Mean cost elective (SD) [n=64] Mean Difference 95% CI for difference Length of stay (days) 12 (7) 9 (5) 3* .5, 6 Episode cost $44,182 (32,582) $28,019 (16,306) $16,163* $3,612, $28,714 Pre- hospital $310 (1,700) $149 (200) $162 -$463. $787 Operation $9,999 (5,546) $9,763 (2,880) $236 -$1,907, $2,380 ICU $15,906 (23,938) $6,500 (10,817) $9,406* $266, $18,546 Blood products $3,743 (1,543) $373 (954) $3,370** $1,159 $5,581 Laboratory costs $849 (623) $402 (337) $447*** $208, $686 Ward costs $10,454 (7,918) $9,498 (3,988) $956 -$1,747, $3,661 Other $2,918 (3,851) $1,335 (2,053) $1,583* $90, $3,076 *p <0.05, **p <0.01, ***p <0.001 Costs of all AAA repairs between elective and ruptured groups, including EVARThere were 53 elective and two rupture EVARs. The mean total inpatient cost of elective EVAR was $31,023 per patient. The mean cost of the aortic stent graft for those who underwent EVAR was $14,765. Table 5 shows the results of a cost analysis of all AAA repairs, including EVAR, during the study period. This analysis included 117 elective AAA and 42 ruptured AAA. The demographics and risk factors relevant to this analysis are summarised in Table 6. The mean total cost in the elective group was $29,380 and $38,590 in the ruptured group. There was a trend towards a lower mean cost in the elective group, but the mean difference of $9,210 was not statistically significant (95%CI: -$404, $18,825; p=0.06). Blood products and laboratory costs were significantly higher in the ruptured group. The mean length of stay was 3 days shorter in the elective group than in the rupture group (95%CI: 0.5, 6; p=0.02). When comparing the elective group including EVAR to the elective group excluding EVAR, there appears to be a higher operation cost and a lower ICU cost.Table 5: Statistical comparison of length of stay and costs between rupture and elective groups including EVAR. Mean cost ruptured (SD) [n=42] Mean cost elective (SD) [n=117] Mean Difference 95% CI for difference Length of stay (days) 10 (8) 7 (5) 3* 0.5, 6 Total cost $38,590 (29,880) $29,380 (13,641) $9,210 -$404, $18,825 Pre-hospital $242 (697) $129 (162) $113 -$344, $568 Operation $10,400 (5,912) $17,537 (10,321) -$7,137 -$9,750, $4,524 ICU $12,619 (21,349) $3,590 (8,602) $9,029 -$2,206, $15,850 Blood products $4,197 (5,992) $260 (743) $3,937*** $2,065, $5,809 Laboratory costs $706 (586) $291 (308) $415*** $224, $606 Ward costs $7,963 (7,307) $6,191 (4,810) $1,772 -$657, $4,202 Other $2,460 (3,558) $1,388 (1,885) $1,072 -$75, $2,219 *p <0.05, **p <0.01, ***p <0.001 Table 6: Summary of demographics and risk factors for elective and rupture groups including EVAR. Elective Ruptured n= 117 42 Median age (range) 74 (57-86) 75 (49-86) Males (%) 88 (75) 35 (83) Diabetes (%) 11 (9) 4 (10) Smoking history (%) 72 (62) 17 (40) Hypertension (%) 73 (63) 20 (48) Ischaemic heart disease (%) 39 (33) 8 (19) On statin therapy (%) 61 (52) 14 (33) On antiplatelet therapy (%) 67 (57) 14 (33) Median ASA\u2020 (range) 3 (2-4) 3 (2-5) 30 day mortality (%) 0 (0) 11 (26) Costs of AAA repair between EVAR elective and open elective groupsTable 7 shows the difference in mean cost between the 53 patients who had EVAR and the 64 patients who had open procedures as an elective case. The EVAR group had a 5 day (95%CI: -7, -4; p<0.0001) shorter length of hospital stay than open AAA repair. However, there was no difference in total inpatient cost. The mean difference in operation cost was in the EVAR group, significantly higher than in the open group at $17,163 (95%CI: $14,861, $19,463; p<.0001), while the mean difference in ICU and ward costs were significantly lower.Table 7: Statistical comparison of length of stay and costs between EVAR elective and open elective groups. Mean cost EVAR elective (SD) [n=53] Mean cost open elective (SD) [n=64] Mean Difference 95% CI for difference Length of stay (days) 4 (3) 9 (5) -5*** -7, -4 Total cost $31,023 (9,380) $28,

Summary

Abstract

Aim

Population-based screening for abdominal aortic aneurysms (AAA) is being considered in New Zealand. However, there is a lack of data to support its cost effectiveness in this country. The aim of this study was to compare the hospital costs of AAA repair in emergency and elective cases over a 3-year period in a single centre in New Zealand.

Method

A retrospective observational analysis of consecutive patients undergoing elective and emergency AAA repair during the study period (January 2009 to December 2011) was performed.

Results

A total of 169 AAA repairs were performed during the study period, of which 114 (67%) were open repairs. Sixty-four of these were open elective AAA repairs, 40 were open ruptured repairs, and 10 were open symptomatic repairs. The mean inpatient cost was $38,804 for open ruptured AAA repair and $28,019 for open elective repair, a difference of $10,785 (95%CI: $249 to $21,321; p=.045). The costs of blood products and laboratory investigations were significantly greater in the ruptured group than the elective. There was no significant difference in length of hospital admission between the groups.

Conclusion

This study demonstrates that ruptured AAA repairs are more expensive than elective AAA repairs, despite no difference in length of hospital stay. The estimated inpatient costs documented in this study for each type of repair can be used for cost-effectiveness analysis in New Zealand. A screening program that reduces the incidence of surgery for ruptured AAA could decrease the average inpatient cost of AAA repairs.

Author Information

Kevin Niall Peek, Canterbury District Health Board, Christchurch; Manar Khashram, Vascular Surgery Trainee, Department of Vascular Endovascular and Transplant Surgery, Christchurch Hospital, Christchurch; J Elisabeth Wells, Biostatistics and Computational Biology, Department of Population Health, University of Otago, Christchurch; Justin A Roake, Vascular Surgeon, Department of Vascular Endovascular and Transplant Surgery, Christchurch Hospital, Christchurch.

Acknowledgements

Chris Hoar, Business Manager, Medical & Surgical Division, Christchurch Public Hospital; Keith Todd, Service Manager - Vascular & Cardiothoracic, Medical /Surgical Division, Canterbury District Health Board.

Correspondence

Manar Khashram, Department of Vascular Endovascular and Transplant Surgery, Christchurch Hospital, Private Bag 4710, Christchurch.

Correspondence Email

manar.khashram@gmail.com

Competing Interests

Nil

-- Nair N, Shaw C, Sarfati D, Stanley J. Abdominal aortic aneurysm disease in New Zealand: epidemiology and burden between 2002 and 2006. N Z Med J. 2012; 125: 10-20. Svensj\u00f6 S, Bj\u00f6rck M, G\u00fcrtelschmid M, et al. Low prevalence of a

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Abdominal aortic aneurysms (AAA) are a significant cause of mortality in New Zealand accounting for about 236 deaths per year, of which 80% are attributed to ruptures.1 Recent international studies suggest that the prevalence of AAA is about 2% in men aged 65.2,3 The natural history of AAA is a progressive increase in diameter to the point of rupture. The risk of aneurysm rupture increases with increasing diameter.Approximately, 30% of patients with a ruptured AAA die pre-hospital. Of those undergoing repair, the mortality rate is approximately 35%. There is an overall mortality rate of up to 85%.4 However, when detected prior to rupture, they can be treated electively by open or endovascular methods, with open surgical procedures carrying a mortality of 3-10%.5Four randomised controlled trials summarised by a meta-analysis showed that ultrasound AAA screening was associated with a significant reduction of AAA-related mortality in men aged 65-79 years.5 There are six countries that offer screening or are in the process of developing screening programs for AAA.6 Currently, no such programme exists in New Zealand, although consideration has been given to initiating one. Nair and colleagues have documented the burden of AAA in New Zealand from 2002 until 2006.1 An average of 267 AAA were repaired electively, and a further 87 repaired as an emergency each year. Mortality rates for elective and emergency repairs were 6.7% and 35.2% respectively. Almost all AAA deaths occurred in people aged over 65 years.1 Sandiford et al report declining incidence and mortality rates of AAA in New Zealand since 1991, which may be attributable to a reduction in smoking rates and the use of statins to control serum cholesterol.7 In New Zealand, the prevalence of AAA in the population is still unknown, but in a selected population undergoing CT colonography for gastrointestinal symptoms, a prevalence of 9.1 % in men 65-75 years old was observed. 8 This highlights the burden of AAA disease in New Zealand and the importance of an AAA screening program.Cost analysis comparing open aneurysm repair (OAR) and endovascular aneurysm repair (EVAR) has been assessed in randomised controlled trials.9,10 However, inpatient costs of AAA repair in the contemporary clinical setting have not been assessed in New Zealand.11 The aim of this study was to compare the hospital costs of AAA repair in emergency and elective cases over a 3-year period in a tertiary referral vascular centre.MethodsThis was a retrospective, observational analysis of consecutive patients undergoing elective and emergency AAA repair, from 1 January 2009 until 31 December 2011, in a single New Zealand centre.The exclusion criteria was: isolated iliac aneurysms with open or endovascular methods; non-aneurysmal aortic surgery for occlusive disease; complex fenestrated and branched endovascular aneurysm repair (EVAR) grafts; or treatment for infected aortic grafts or mycotic aneurysms.The unit s protocol for all patients undergoing open AAA repair was to stay in ICU for one night minimum. There is no routine ICU or HDU for EVAR patients. The majority of elective cases were admitted into hospital on the same day of surgery and EVAR patients receive their first imaging surveillance (ultrasound) at 6 weeks post-operatively, unless there were any clinical concerns.Patients were identified using a prospectively-collected vascular database and the hospital s decision support tool. Patients clinical presentations were defined into three groups: ruptured AAA repair; symptomatic but not ruptured AAA repair; or elective AAA repair. Information for each patient was extracted from the vascular database, including demographics, vascular risk factors and length of stay (LOS). The hospital s decision clinical coding data was used to extract the cost of each admission. The costing system uses several techniques used to derive each inpatient costs. Inventoried items (eg, theatre materials, grafts, blood products) are recorded for each admission and are assigned a value based on the cost of the product to the DHB. There is a similar process with hospital services (eg, labs, ECHO, radiology). Nursing and doctor s hours are assigned a value based on the time spent in a particular location of for the patient (eg, theatre, ICU, ward) which reflect the differences in staff numbers and salary for each. The time of other health care providers is also logged and includes physiotherapy, social work, phlebotomy, and inpatient specialist referral. The components used to determine the cost of each admission were examined and grouped into the following categories for analysis: pre-hospital (including pre-admission and air ambulance costs), operation, intensive care, blood products, laboratory and other.Four separate analyses were performed: The difference in costs of OAR between elective and ruptured groups was examined. EVAR patients were not included in the primary analysis as it was hypothesised that an unequal distribution of EVAR, with a high stent graft cost, in the elective group would affect the comparability of the groups. In addition, the use of EVAR for treating ruptured AAA has not been widely adopted at our institution. OAR were examined, excluding patients who died in less than 4 days, as it was hypothesised that early mortality would lead to a lower difference of cost between the groups. All patients presentations who had OAR and EVAR were analysed. OAR was compared to EVAR in the elective cases only to provide context for the other analyses and to provide data for future modelling. Analyses were carried out using SAS/STAT 12.1 software. All t-tests used the Satterthwaite approximation for unequal variances. Statistical significance was set at p<0.05. Although cost distributions were inspected and found to be skewed with long tails of high values, analyses focused on mean costs rather than the medians, as these are what are relevant to health care planners.12ResultsA total of 169 AAA were repaired during the study period. This consisted of 117 (69.2%) elective repairs (64 OAR and 53 EVAR), 42 (24.9%) ruptured repairs (40 OAR and 2 EVAR), and 10 (5.9%) symptomatic repairs (all OAR). The total number of ruptured AAA presenting to the hospital during this period was 89, of which 47 (53%) were managed non-operatively, either dying before reaching the operating theatre or after having decided not to undergo operation. Demographics and risk factors for each group is summarised in Table 1. The median age for the elective, ruptured, and symptomatic groups was 73, 77 and 74 years, respectively. All three groups consisted primarily of male patients. The elective group had a higher proportion of patients with ischaemic heart disease, who were receiving statin and antiplatelet therapy compared to the other groups. The symptomatic group had the highest proportion of patients with a recorded history of smoking and hypertension. There was no 30-day mortality in the elective or symptomatic groups. The 30-day mortality of the ruptured aneurysms repaired was 11 out of 42 (26.2%).Table 1: Summary of demographics and risk factors for open AAA repairs. Elective Ruptured Symptomatic n= 64 40 10 Median age (range) 73 (57-86) 77 (49-86) 74 (62-82) Males (%) 46 (72) 34 (85) 8 (80) Diabetes (%) 3 (4) 4 (10) 0 Smoking history (%) 37 (58) 17 (42) 6 (60) Hypertension (%) 34 (53) 18 (45) 7 (70) Ischaemic heart disease (%) 20 (31) 6 (15) 2 (20) On statin therapy (%) 35 (55) 13 (33) 3 (30) On antiplatelet therapy (%) 37 (61) 13 (33) 5 (50) Median ASA\u2020 (range) 3 (2-4) 3 (2-5) 3 (2-3) 30-day mortality (%) 0 11 (28) 0 \u2020American Society of Anesthesiologists physical status classification systemThirteen out of the 117 (11%) elective patients, and 7 out of the 42 (17%) of ruptured patients, were discharged to a rehabilitation facility. The median length of stay (LOS) in rehabilitation for the elective and rupture group was 8 and 12 days respectively.Primary analysis: Costs of open AAA repairs between elective and ruptured groups114 open AAA were repaired during the study period. Of those, 64 were elective repairs, 40 were ruptures and 10 were symptomatic repairs. Figure 1 demonstrates the number of open repairs performed annually stratified by the indication for surgery.Figure 1: The number of open AAA repairs performed in each year of the study period stratified by the indication for surgery. The costs and LOS amongst the groups included in the primary analysis is presented in Table 2. The mean cost per patient in the open elective group was $28,019. In the open ruptured group it was $38,804, and for the open symptomatic group it was $33,743. The distribution of the total cost per group is demonstrated by the box plots in Figure 2. The mean LOS was 9 days for elective, 10 days for rupture, and 12 days for symptomatic admissions. The most significant categories contributing to the total costs amongst the three groups were operation, ward and ICU costs, with overall means of $9,644, $9,343 and $9,009, respectively. The median time from start of anaesthetic until leaving operating theatre for the elective, rupture group and the symptomatic groups was 265, 205 and 224 minutes respectively.Table 2: Costs and length of stay of open AAA repair in the primary analysis. Group Variable Mean (SD) Median (Q1-Q3) Elective (n=64) Length of stay (days) 9 (5) 8 (6-11) Total cost $28,019 (16,306) $24,628 ($21,012-$29,306) Pre-hospital $149 (200) $159 ($0-$198) Operation $9,763 (2,880) $8,413 ($6,568-$9,618) ICU $6,500 (10817) $4,487 ($3,905-$5,113) Blood products $373 (954) $49 ($0-$546) Laboratory costs $402 (337) $327 ($237-$459) Ward costs $9,498 (3988) $9,053 ($7,157-$11,790) Other $1,335 (2053) $666 ($358-$1,225) Ruptured (n=40) Length of stay (days) 10 (8) 9 (4-16) Total cost $38,804 (30,620) $31,895 ($24,691-$40,7301) Pre-hospital $241 (1,497) $0 ($0-$0) \u2020 Operation $9,682 (5,061) $9,115 ($6,960-$11,346) ICU $13,250 (21,693) $7,868 ($3,857-$14,166) Blood products $4,404 (6,069) $2,328 ($1,195-$4,772) Laboratory costs $731 (591) $549 ($422-$884) Ward costs $8,170 (7,431) $7,400 ($610-$13,229) Other $2,327 (3559) $1,248 ($562-$2,298) Symptomatic (n=10) Length of stay (days) 12 (9) 8 (7-15) Total cost $33, 743 (19,351) $25,891 ($21,973-$36,439) Pre- hospital $432 (869) $0 ($0-$179) Operation $8,740 (1,414) $9,083 ($8,315-$9,774) ICU $8,108 (7,079) $4,679 ($3,975-$8,854) Blood products $905 (1,026) $820 ($43-$1,225) Laboratory costs $666 (558) $508 ($306-$764) Ward costs $13,050 (10,378) $7,673 ($6,938-$17,071) Other $1,842 (1,612) $1,344 ($617-$2,013) \u20203 patients Figure 2: Box plots demonstrating the distribution of inpatient costs in each study group. Table 3 shows the statistical comparison between the open rupture and elective groups. There was a significant difference between the mean inpatient cost of open ruptured AAA repair and open elective AAA repair of $10,785 (95%CI: $249, $21,321; p=0.045). The cost of blood products was $4,031 greater (95%CI: $2,077, $5,985; p=0.0002), and the cost of laboratory investigations was $329 greater (95%CI: $123, $534; p=0.002) in the ruptured group than the elective group. There was no difference in pre-hospital, operation, ICU, ward or \u2018other costs between the groups. There was no significant difference in LOS between the two groups.Table 3: Statistical comparison of length of stay and costs between open ruptured and elective groups. Mean cost ruptured (SD) [n=40] Mean cost elective (SD) [n=64] Mean Difference 95% CI for difference Length of stay (days) 10 (8) 9 (5) 1 -2, 4 Total cost $38,804 (30,620) $28,019 (16,306) $10,785* $249, $21,321 Pre- hospital $241 (1,497) $149 (200) $92 -$389, $573 Operation $9,682 (5,061) $9,763 (2,880) -$81 -$1,839, $1,677 ICU $13,250 (21,693) $6,500 (10,817) $6,750 -$650, $14,150 Blood products $4,404 (6,069) $373 (954) $4,031*** $2,077, $5,985 Laboratory costs $731 (591) $402 (337) $329** $123, $534 Ward costs $8,170 (7,431) $9,498 (3,988) -$1,328 -$3,888, $1,231 Other $2,327 (3,559) $1,335 (2,053) $992 -$247, $2,231 *p <0.05, **p <0.01, ***p <0.001Costs of open AAA repairs between elective and ruptured groups, excluding early (<4 day) mortalityOf the 40 patients with ruptured AAA who had a repair, nine died within four days. The mean difference of costs between ruptured and elective groups with early mortality excluded is presented in Table 4. In this analysis, there was a significant mean difference of $16,163 (95%CI: $3,612, $28,714; p=0.01) between open ruptured AAA repair and open elective AAA repair. ICU, blood product, laboratory and \u2018other costs were significantly higher in the ruptured group, while pre-hospital, operation and ward costs were not different.Table 4: Statistical comparison of length of stay and costs between open rupture and elective groups with early mortality (<4 days) excluded. Mean cost ruptured (SD) [n=31] Mean cost elective (SD) [n=64] Mean Difference 95% CI for difference Length of stay (days) 12 (7) 9 (5) 3* .5, 6 Episode cost $44,182 (32,582) $28,019 (16,306) $16,163* $3,612, $28,714 Pre- hospital $310 (1,700) $149 (200) $162 -$463. $787 Operation $9,999 (5,546) $9,763 (2,880) $236 -$1,907, $2,380 ICU $15,906 (23,938) $6,500 (10,817) $9,406* $266, $18,546 Blood products $3,743 (1,543) $373 (954) $3,370** $1,159 $5,581 Laboratory costs $849 (623) $402 (337) $447*** $208, $686 Ward costs $10,454 (7,918) $9,498 (3,988) $956 -$1,747, $3,661 Other $2,918 (3,851) $1,335 (2,053) $1,583* $90, $3,076 *p <0.05, **p <0.01, ***p <0.001 Costs of all AAA repairs between elective and ruptured groups, including EVARThere were 53 elective and two rupture EVARs. The mean total inpatient cost of elective EVAR was $31,023 per patient. The mean cost of the aortic stent graft for those who underwent EVAR was $14,765. Table 5 shows the results of a cost analysis of all AAA repairs, including EVAR, during the study period. This analysis included 117 elective AAA and 42 ruptured AAA. The demographics and risk factors relevant to this analysis are summarised in Table 6. The mean total cost in the elective group was $29,380 and $38,590 in the ruptured group. There was a trend towards a lower mean cost in the elective group, but the mean difference of $9,210 was not statistically significant (95%CI: -$404, $18,825; p=0.06). Blood products and laboratory costs were significantly higher in the ruptured group. The mean length of stay was 3 days shorter in the elective group than in the rupture group (95%CI: 0.5, 6; p=0.02). When comparing the elective group including EVAR to the elective group excluding EVAR, there appears to be a higher operation cost and a lower ICU cost.Table 5: Statistical comparison of length of stay and costs between rupture and elective groups including EVAR. Mean cost ruptured (SD) [n=42] Mean cost elective (SD) [n=117] Mean Difference 95% CI for difference Length of stay (days) 10 (8) 7 (5) 3* 0.5, 6 Total cost $38,590 (29,880) $29,380 (13,641) $9,210 -$404, $18,825 Pre-hospital $242 (697) $129 (162) $113 -$344, $568 Operation $10,400 (5,912) $17,537 (10,321) -$7,137 -$9,750, $4,524 ICU $12,619 (21,349) $3,590 (8,602) $9,029 -$2,206, $15,850 Blood products $4,197 (5,992) $260 (743) $3,937*** $2,065, $5,809 Laboratory costs $706 (586) $291 (308) $415*** $224, $606 Ward costs $7,963 (7,307) $6,191 (4,810) $1,772 -$657, $4,202 Other $2,460 (3,558) $1,388 (1,885) $1,072 -$75, $2,219 *p <0.05, **p <0.01, ***p <0.001 Table 6: Summary of demographics and risk factors for elective and rupture groups including EVAR. Elective Ruptured n= 117 42 Median age (range) 74 (57-86) 75 (49-86) Males (%) 88 (75) 35 (83) Diabetes (%) 11 (9) 4 (10) Smoking history (%) 72 (62) 17 (40) Hypertension (%) 73 (63) 20 (48) Ischaemic heart disease (%) 39 (33) 8 (19) On statin therapy (%) 61 (52) 14 (33) On antiplatelet therapy (%) 67 (57) 14 (33) Median ASA\u2020 (range) 3 (2-4) 3 (2-5) 30 day mortality (%) 0 (0) 11 (26) Costs of AAA repair between EVAR elective and open elective groupsTable 7 shows the difference in mean cost between the 53 patients who had EVAR and the 64 patients who had open procedures as an elective case. The EVAR group had a 5 day (95%CI: -7, -4; p<0.0001) shorter length of hospital stay than open AAA repair. However, there was no difference in total inpatient cost. The mean difference in operation cost was in the EVAR group, significantly higher than in the open group at $17,163 (95%CI: $14,861, $19,463; p<.0001), while the mean difference in ICU and ward costs were significantly lower.Table 7: Statistical comparison of length of stay and costs between EVAR elective and open elective groups. Mean cost EVAR elective (SD) [n=53] Mean cost open elective (SD) [n=64] Mean Difference 95% CI for difference Length of stay (days) 4 (3) 9 (5) -5*** -7, -4 Total cost $31,023 (9,380) $28,

Summary

Abstract

Aim

Population-based screening for abdominal aortic aneurysms (AAA) is being considered in New Zealand. However, there is a lack of data to support its cost effectiveness in this country. The aim of this study was to compare the hospital costs of AAA repair in emergency and elective cases over a 3-year period in a single centre in New Zealand.

Method

A retrospective observational analysis of consecutive patients undergoing elective and emergency AAA repair during the study period (January 2009 to December 2011) was performed.

Results

A total of 169 AAA repairs were performed during the study period, of which 114 (67%) were open repairs. Sixty-four of these were open elective AAA repairs, 40 were open ruptured repairs, and 10 were open symptomatic repairs. The mean inpatient cost was $38,804 for open ruptured AAA repair and $28,019 for open elective repair, a difference of $10,785 (95%CI: $249 to $21,321; p=.045). The costs of blood products and laboratory investigations were significantly greater in the ruptured group than the elective. There was no significant difference in length of hospital admission between the groups.

Conclusion

This study demonstrates that ruptured AAA repairs are more expensive than elective AAA repairs, despite no difference in length of hospital stay. The estimated inpatient costs documented in this study for each type of repair can be used for cost-effectiveness analysis in New Zealand. A screening program that reduces the incidence of surgery for ruptured AAA could decrease the average inpatient cost of AAA repairs.

Author Information

Kevin Niall Peek, Canterbury District Health Board, Christchurch; Manar Khashram, Vascular Surgery Trainee, Department of Vascular Endovascular and Transplant Surgery, Christchurch Hospital, Christchurch; J Elisabeth Wells, Biostatistics and Computational Biology, Department of Population Health, University of Otago, Christchurch; Justin A Roake, Vascular Surgeon, Department of Vascular Endovascular and Transplant Surgery, Christchurch Hospital, Christchurch.

Acknowledgements

Chris Hoar, Business Manager, Medical & Surgical Division, Christchurch Public Hospital; Keith Todd, Service Manager - Vascular & Cardiothoracic, Medical /Surgical Division, Canterbury District Health Board.

Correspondence

Manar Khashram, Department of Vascular Endovascular and Transplant Surgery, Christchurch Hospital, Private Bag 4710, Christchurch.

Correspondence Email

manar.khashram@gmail.com

Competing Interests

Nil

-- Nair N, Shaw C, Sarfati D, Stanley J. Abdominal aortic aneurysm disease in New Zealand: epidemiology and burden between 2002 and 2006. N Z Med J. 2012; 125: 10-20. Svensj\u00f6 S, Bj\u00f6rck M, G\u00fcrtelschmid M, et al. Low prevalence of a

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Abdominal aortic aneurysms (AAA) are a significant cause of mortality in New Zealand accounting for about 236 deaths per year, of which 80% are attributed to ruptures.1 Recent international studies suggest that the prevalence of AAA is about 2% in men aged 65.2,3 The natural history of AAA is a progressive increase in diameter to the point of rupture. The risk of aneurysm rupture increases with increasing diameter.Approximately, 30% of patients with a ruptured AAA die pre-hospital. Of those undergoing repair, the mortality rate is approximately 35%. There is an overall mortality rate of up to 85%.4 However, when detected prior to rupture, they can be treated electively by open or endovascular methods, with open surgical procedures carrying a mortality of 3-10%.5Four randomised controlled trials summarised by a meta-analysis showed that ultrasound AAA screening was associated with a significant reduction of AAA-related mortality in men aged 65-79 years.5 There are six countries that offer screening or are in the process of developing screening programs for AAA.6 Currently, no such programme exists in New Zealand, although consideration has been given to initiating one. Nair and colleagues have documented the burden of AAA in New Zealand from 2002 until 2006.1 An average of 267 AAA were repaired electively, and a further 87 repaired as an emergency each year. Mortality rates for elective and emergency repairs were 6.7% and 35.2% respectively. Almost all AAA deaths occurred in people aged over 65 years.1 Sandiford et al report declining incidence and mortality rates of AAA in New Zealand since 1991, which may be attributable to a reduction in smoking rates and the use of statins to control serum cholesterol.7 In New Zealand, the prevalence of AAA in the population is still unknown, but in a selected population undergoing CT colonography for gastrointestinal symptoms, a prevalence of 9.1 % in men 65-75 years old was observed. 8 This highlights the burden of AAA disease in New Zealand and the importance of an AAA screening program.Cost analysis comparing open aneurysm repair (OAR) and endovascular aneurysm repair (EVAR) has been assessed in randomised controlled trials.9,10 However, inpatient costs of AAA repair in the contemporary clinical setting have not been assessed in New Zealand.11 The aim of this study was to compare the hospital costs of AAA repair in emergency and elective cases over a 3-year period in a tertiary referral vascular centre.MethodsThis was a retrospective, observational analysis of consecutive patients undergoing elective and emergency AAA repair, from 1 January 2009 until 31 December 2011, in a single New Zealand centre.The exclusion criteria was: isolated iliac aneurysms with open or endovascular methods; non-aneurysmal aortic surgery for occlusive disease; complex fenestrated and branched endovascular aneurysm repair (EVAR) grafts; or treatment for infected aortic grafts or mycotic aneurysms.The unit s protocol for all patients undergoing open AAA repair was to stay in ICU for one night minimum. There is no routine ICU or HDU for EVAR patients. The majority of elective cases were admitted into hospital on the same day of surgery and EVAR patients receive their first imaging surveillance (ultrasound) at 6 weeks post-operatively, unless there were any clinical concerns.Patients were identified using a prospectively-collected vascular database and the hospital s decision support tool. Patients clinical presentations were defined into three groups: ruptured AAA repair; symptomatic but not ruptured AAA repair; or elective AAA repair. Information for each patient was extracted from the vascular database, including demographics, vascular risk factors and length of stay (LOS). The hospital s decision clinical coding data was used to extract the cost of each admission. The costing system uses several techniques used to derive each inpatient costs. Inventoried items (eg, theatre materials, grafts, blood products) are recorded for each admission and are assigned a value based on the cost of the product to the DHB. There is a similar process with hospital services (eg, labs, ECHO, radiology). Nursing and doctor s hours are assigned a value based on the time spent in a particular location of for the patient (eg, theatre, ICU, ward) which reflect the differences in staff numbers and salary for each. The time of other health care providers is also logged and includes physiotherapy, social work, phlebotomy, and inpatient specialist referral. The components used to determine the cost of each admission were examined and grouped into the following categories for analysis: pre-hospital (including pre-admission and air ambulance costs), operation, intensive care, blood products, laboratory and other.Four separate analyses were performed: The difference in costs of OAR between elective and ruptured groups was examined. EVAR patients were not included in the primary analysis as it was hypothesised that an unequal distribution of EVAR, with a high stent graft cost, in the elective group would affect the comparability of the groups. In addition, the use of EVAR for treating ruptured AAA has not been widely adopted at our institution. OAR were examined, excluding patients who died in less than 4 days, as it was hypothesised that early mortality would lead to a lower difference of cost between the groups. All patients presentations who had OAR and EVAR were analysed. OAR was compared to EVAR in the elective cases only to provide context for the other analyses and to provide data for future modelling. Analyses were carried out using SAS/STAT 12.1 software. All t-tests used the Satterthwaite approximation for unequal variances. Statistical significance was set at p<0.05. Although cost distributions were inspected and found to be skewed with long tails of high values, analyses focused on mean costs rather than the medians, as these are what are relevant to health care planners.12ResultsA total of 169 AAA were repaired during the study period. This consisted of 117 (69.2%) elective repairs (64 OAR and 53 EVAR), 42 (24.9%) ruptured repairs (40 OAR and 2 EVAR), and 10 (5.9%) symptomatic repairs (all OAR). The total number of ruptured AAA presenting to the hospital during this period was 89, of which 47 (53%) were managed non-operatively, either dying before reaching the operating theatre or after having decided not to undergo operation. Demographics and risk factors for each group is summarised in Table 1. The median age for the elective, ruptured, and symptomatic groups was 73, 77 and 74 years, respectively. All three groups consisted primarily of male patients. The elective group had a higher proportion of patients with ischaemic heart disease, who were receiving statin and antiplatelet therapy compared to the other groups. The symptomatic group had the highest proportion of patients with a recorded history of smoking and hypertension. There was no 30-day mortality in the elective or symptomatic groups. The 30-day mortality of the ruptured aneurysms repaired was 11 out of 42 (26.2%).Table 1: Summary of demographics and risk factors for open AAA repairs. Elective Ruptured Symptomatic n= 64 40 10 Median age (range) 73 (57-86) 77 (49-86) 74 (62-82) Males (%) 46 (72) 34 (85) 8 (80) Diabetes (%) 3 (4) 4 (10) 0 Smoking history (%) 37 (58) 17 (42) 6 (60) Hypertension (%) 34 (53) 18 (45) 7 (70) Ischaemic heart disease (%) 20 (31) 6 (15) 2 (20) On statin therapy (%) 35 (55) 13 (33) 3 (30) On antiplatelet therapy (%) 37 (61) 13 (33) 5 (50) Median ASA\u2020 (range) 3 (2-4) 3 (2-5) 3 (2-3) 30-day mortality (%) 0 11 (28) 0 \u2020American Society of Anesthesiologists physical status classification systemThirteen out of the 117 (11%) elective patients, and 7 out of the 42 (17%) of ruptured patients, were discharged to a rehabilitation facility. The median length of stay (LOS) in rehabilitation for the elective and rupture group was 8 and 12 days respectively.Primary analysis: Costs of open AAA repairs between elective and ruptured groups114 open AAA were repaired during the study period. Of those, 64 were elective repairs, 40 were ruptures and 10 were symptomatic repairs. Figure 1 demonstrates the number of open repairs performed annually stratified by the indication for surgery.Figure 1: The number of open AAA repairs performed in each year of the study period stratified by the indication for surgery. The costs and LOS amongst the groups included in the primary analysis is presented in Table 2. The mean cost per patient in the open elective group was $28,019. In the open ruptured group it was $38,804, and for the open symptomatic group it was $33,743. The distribution of the total cost per group is demonstrated by the box plots in Figure 2. The mean LOS was 9 days for elective, 10 days for rupture, and 12 days for symptomatic admissions. The most significant categories contributing to the total costs amongst the three groups were operation, ward and ICU costs, with overall means of $9,644, $9,343 and $9,009, respectively. The median time from start of anaesthetic until leaving operating theatre for the elective, rupture group and the symptomatic groups was 265, 205 and 224 minutes respectively.Table 2: Costs and length of stay of open AAA repair in the primary analysis. Group Variable Mean (SD) Median (Q1-Q3) Elective (n=64) Length of stay (days) 9 (5) 8 (6-11) Total cost $28,019 (16,306) $24,628 ($21,012-$29,306) Pre-hospital $149 (200) $159 ($0-$198) Operation $9,763 (2,880) $8,413 ($6,568-$9,618) ICU $6,500 (10817) $4,487 ($3,905-$5,113) Blood products $373 (954) $49 ($0-$546) Laboratory costs $402 (337) $327 ($237-$459) Ward costs $9,498 (3988) $9,053 ($7,157-$11,790) Other $1,335 (2053) $666 ($358-$1,225) Ruptured (n=40) Length of stay (days) 10 (8) 9 (4-16) Total cost $38,804 (30,620) $31,895 ($24,691-$40,7301) Pre-hospital $241 (1,497) $0 ($0-$0) \u2020 Operation $9,682 (5,061) $9,115 ($6,960-$11,346) ICU $13,250 (21,693) $7,868 ($3,857-$14,166) Blood products $4,404 (6,069) $2,328 ($1,195-$4,772) Laboratory costs $731 (591) $549 ($422-$884) Ward costs $8,170 (7,431) $7,400 ($610-$13,229) Other $2,327 (3559) $1,248 ($562-$2,298) Symptomatic (n=10) Length of stay (days) 12 (9) 8 (7-15) Total cost $33, 743 (19,351) $25,891 ($21,973-$36,439) Pre- hospital $432 (869) $0 ($0-$179) Operation $8,740 (1,414) $9,083 ($8,315-$9,774) ICU $8,108 (7,079) $4,679 ($3,975-$8,854) Blood products $905 (1,026) $820 ($43-$1,225) Laboratory costs $666 (558) $508 ($306-$764) Ward costs $13,050 (10,378) $7,673 ($6,938-$17,071) Other $1,842 (1,612) $1,344 ($617-$2,013) \u20203 patients Figure 2: Box plots demonstrating the distribution of inpatient costs in each study group. Table 3 shows the statistical comparison between the open rupture and elective groups. There was a significant difference between the mean inpatient cost of open ruptured AAA repair and open elective AAA repair of $10,785 (95%CI: $249, $21,321; p=0.045). The cost of blood products was $4,031 greater (95%CI: $2,077, $5,985; p=0.0002), and the cost of laboratory investigations was $329 greater (95%CI: $123, $534; p=0.002) in the ruptured group than the elective group. There was no difference in pre-hospital, operation, ICU, ward or \u2018other costs between the groups. There was no significant difference in LOS between the two groups.Table 3: Statistical comparison of length of stay and costs between open ruptured and elective groups. Mean cost ruptured (SD) [n=40] Mean cost elective (SD) [n=64] Mean Difference 95% CI for difference Length of stay (days) 10 (8) 9 (5) 1 -2, 4 Total cost $38,804 (30,620) $28,019 (16,306) $10,785* $249, $21,321 Pre- hospital $241 (1,497) $149 (200) $92 -$389, $573 Operation $9,682 (5,061) $9,763 (2,880) -$81 -$1,839, $1,677 ICU $13,250 (21,693) $6,500 (10,817) $6,750 -$650, $14,150 Blood products $4,404 (6,069) $373 (954) $4,031*** $2,077, $5,985 Laboratory costs $731 (591) $402 (337) $329** $123, $534 Ward costs $8,170 (7,431) $9,498 (3,988) -$1,328 -$3,888, $1,231 Other $2,327 (3,559) $1,335 (2,053) $992 -$247, $2,231 *p <0.05, **p <0.01, ***p <0.001Costs of open AAA repairs between elective and ruptured groups, excluding early (<4 day) mortalityOf the 40 patients with ruptured AAA who had a repair, nine died within four days. The mean difference of costs between ruptured and elective groups with early mortality excluded is presented in Table 4. In this analysis, there was a significant mean difference of $16,163 (95%CI: $3,612, $28,714; p=0.01) between open ruptured AAA repair and open elective AAA repair. ICU, blood product, laboratory and \u2018other costs were significantly higher in the ruptured group, while pre-hospital, operation and ward costs were not different.Table 4: Statistical comparison of length of stay and costs between open rupture and elective groups with early mortality (<4 days) excluded. Mean cost ruptured (SD) [n=31] Mean cost elective (SD) [n=64] Mean Difference 95% CI for difference Length of stay (days) 12 (7) 9 (5) 3* .5, 6 Episode cost $44,182 (32,582) $28,019 (16,306) $16,163* $3,612, $28,714 Pre- hospital $310 (1,700) $149 (200) $162 -$463. $787 Operation $9,999 (5,546) $9,763 (2,880) $236 -$1,907, $2,380 ICU $15,906 (23,938) $6,500 (10,817) $9,406* $266, $18,546 Blood products $3,743 (1,543) $373 (954) $3,370** $1,159 $5,581 Laboratory costs $849 (623) $402 (337) $447*** $208, $686 Ward costs $10,454 (7,918) $9,498 (3,988) $956 -$1,747, $3,661 Other $2,918 (3,851) $1,335 (2,053) $1,583* $90, $3,076 *p <0.05, **p <0.01, ***p <0.001 Costs of all AAA repairs between elective and ruptured groups, including EVARThere were 53 elective and two rupture EVARs. The mean total inpatient cost of elective EVAR was $31,023 per patient. The mean cost of the aortic stent graft for those who underwent EVAR was $14,765. Table 5 shows the results of a cost analysis of all AAA repairs, including EVAR, during the study period. This analysis included 117 elective AAA and 42 ruptured AAA. The demographics and risk factors relevant to this analysis are summarised in Table 6. The mean total cost in the elective group was $29,380 and $38,590 in the ruptured group. There was a trend towards a lower mean cost in the elective group, but the mean difference of $9,210 was not statistically significant (95%CI: -$404, $18,825; p=0.06). Blood products and laboratory costs were significantly higher in the ruptured group. The mean length of stay was 3 days shorter in the elective group than in the rupture group (95%CI: 0.5, 6; p=0.02). When comparing the elective group including EVAR to the elective group excluding EVAR, there appears to be a higher operation cost and a lower ICU cost.Table 5: Statistical comparison of length of stay and costs between rupture and elective groups including EVAR. Mean cost ruptured (SD) [n=42] Mean cost elective (SD) [n=117] Mean Difference 95% CI for difference Length of stay (days) 10 (8) 7 (5) 3* 0.5, 6 Total cost $38,590 (29,880) $29,380 (13,641) $9,210 -$404, $18,825 Pre-hospital $242 (697) $129 (162) $113 -$344, $568 Operation $10,400 (5,912) $17,537 (10,321) -$7,137 -$9,750, $4,524 ICU $12,619 (21,349) $3,590 (8,602) $9,029 -$2,206, $15,850 Blood products $4,197 (5,992) $260 (743) $3,937*** $2,065, $5,809 Laboratory costs $706 (586) $291 (308) $415*** $224, $606 Ward costs $7,963 (7,307) $6,191 (4,810) $1,772 -$657, $4,202 Other $2,460 (3,558) $1,388 (1,885) $1,072 -$75, $2,219 *p <0.05, **p <0.01, ***p <0.001 Table 6: Summary of demographics and risk factors for elective and rupture groups including EVAR. Elective Ruptured n= 117 42 Median age (range) 74 (57-86) 75 (49-86) Males (%) 88 (75) 35 (83) Diabetes (%) 11 (9) 4 (10) Smoking history (%) 72 (62) 17 (40) Hypertension (%) 73 (63) 20 (48) Ischaemic heart disease (%) 39 (33) 8 (19) On statin therapy (%) 61 (52) 14 (33) On antiplatelet therapy (%) 67 (57) 14 (33) Median ASA\u2020 (range) 3 (2-4) 3 (2-5) 30 day mortality (%) 0 (0) 11 (26) Costs of AAA repair between EVAR elective and open elective groupsTable 7 shows the difference in mean cost between the 53 patients who had EVAR and the 64 patients who had open procedures as an elective case. The EVAR group had a 5 day (95%CI: -7, -4; p<0.0001) shorter length of hospital stay than open AAA repair. However, there was no difference in total inpatient cost. The mean difference in operation cost was in the EVAR group, significantly higher than in the open group at $17,163 (95%CI: $14,861, $19,463; p<.0001), while the mean difference in ICU and ward costs were significantly lower.Table 7: Statistical comparison of length of stay and costs between EVAR elective and open elective groups. Mean cost EVAR elective (SD) [n=53] Mean cost open elective (SD) [n=64] Mean Difference 95% CI for difference Length of stay (days) 4 (3) 9 (5) -5*** -7, -4 Total cost $31,023 (9,380) $28,

Summary

Abstract

Aim

Population-based screening for abdominal aortic aneurysms (AAA) is being considered in New Zealand. However, there is a lack of data to support its cost effectiveness in this country. The aim of this study was to compare the hospital costs of AAA repair in emergency and elective cases over a 3-year period in a single centre in New Zealand.

Method

A retrospective observational analysis of consecutive patients undergoing elective and emergency AAA repair during the study period (January 2009 to December 2011) was performed.

Results

A total of 169 AAA repairs were performed during the study period, of which 114 (67%) were open repairs. Sixty-four of these were open elective AAA repairs, 40 were open ruptured repairs, and 10 were open symptomatic repairs. The mean inpatient cost was $38,804 for open ruptured AAA repair and $28,019 for open elective repair, a difference of $10,785 (95%CI: $249 to $21,321; p=.045). The costs of blood products and laboratory investigations were significantly greater in the ruptured group than the elective. There was no significant difference in length of hospital admission between the groups.

Conclusion

This study demonstrates that ruptured AAA repairs are more expensive than elective AAA repairs, despite no difference in length of hospital stay. The estimated inpatient costs documented in this study for each type of repair can be used for cost-effectiveness analysis in New Zealand. A screening program that reduces the incidence of surgery for ruptured AAA could decrease the average inpatient cost of AAA repairs.

Author Information

Kevin Niall Peek, Canterbury District Health Board, Christchurch; Manar Khashram, Vascular Surgery Trainee, Department of Vascular Endovascular and Transplant Surgery, Christchurch Hospital, Christchurch; J Elisabeth Wells, Biostatistics and Computational Biology, Department of Population Health, University of Otago, Christchurch; Justin A Roake, Vascular Surgeon, Department of Vascular Endovascular and Transplant Surgery, Christchurch Hospital, Christchurch.

Acknowledgements

Chris Hoar, Business Manager, Medical & Surgical Division, Christchurch Public Hospital; Keith Todd, Service Manager - Vascular & Cardiothoracic, Medical /Surgical Division, Canterbury District Health Board.

Correspondence

Manar Khashram, Department of Vascular Endovascular and Transplant Surgery, Christchurch Hospital, Private Bag 4710, Christchurch.

Correspondence Email

manar.khashram@gmail.com

Competing Interests

Nil

-- Nair N, Shaw C, Sarfati D, Stanley J. Abdominal aortic aneurysm disease in New Zealand: epidemiology and burden between 2002 and 2006. N Z Med J. 2012; 125: 10-20. Svensj\u00f6 S, Bj\u00f6rck M, G\u00fcrtelschmid M, et al. Low prevalence of a

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