Comparative clinical effectiveness and cost effectiveness of endovascular strategy v open repair for ruptured abdominal aortic aneurysm: three year results of the IMPROVE randomised trial

Abstract

Objective To assess the three year clinical outcomes and cost effectiveness of a strategy of endovascular repair (if aortic morphology is suitable, open repair if not) versus open repair for patients with suspected ruptured abdominal aortic aneurysm.Design Randomised controlled trial.Setting 30 vascular centres (29 in UK, one in Canada), 2009-16.Participants 613 eligible patients (480 men) with a clinical diagnosis of ruptured aneurysm, of whom 502 underwent emergency repair for rupture.Interventions 316 patients were randomised to an endovascular strategy (275 with confirmed rupture) and 297 to open repair (261 with confirmed rupture).Main outcome measures Mortality, with reinterventions after aneurysm repair, quality of life, and hospital costs to three years as secondary measures.Results The maximum follow-up for mortality was 7.1 years, with two patients in each group lost to follow-up by three years. After similar mortality by 90 days, in the mid-term (three months to three years) there were fewer deaths in the endovascular than the open repair group (hazard ratio 0.57, 95% confidence interval 0.36 to 0.90), leading to lower mortality at three years (48% v 56%), but by seven years mortality was about 60% in each group (hazard ratio 0.92, 0.75 to 1.13). Results for the 502 patients with repaired ruptures were more pronounced: three year mortality was lower in the endovascular strategy group (42% v 54%; odds ratio 0.62, 0.43 to 0.88), but after seven years there was no clear difference between the groups (hazard ratio 0.86, 0.68 to 1.08). Reintervention rates up to three years were not significantly different between the randomised groups (hazard ratio 1.02, 0.79 to 1.32); the initial rapid rate of reinterventions was followed by a much slower mid-term reintervention rate in both groups. The early higher average quality of life in the endovascular strategy versus open repair group, coupled with the lower mortality at three years, led to a gain in average quality adjusted life years (QALYs) at three years of 0.17 (95% confidence interval 0.00 to 0.33). The endovascular strategy group spent fewer days in hospital and had lower average costs of -£2605 (95% confidence interval -£5966 to £702) (about €2813; $3439). The probability that the endovascular strategy is cost effective was >90% at all levels of willingness to pay for a QALY gain.Conclusions At three years, compared with open repair, an endovascular strategy for suspected ruptured abdominal aortic aneurysm was associated with a survival advantage, a gain in QALYs, similar levels of reintervention, and reduced costs, and this strategy was cost effective. These findings support the increasing use of an endovascular strategy, with wider availability of emergency endovascular repair.Trial registration Current Controlled Trials ISRCTN48334791; ClinicalTrials NCT00746122.

Fig 1 Flow of patients to three years after randomisation. *Includes 26 patients who had open repairs in breach of protocol; †includes 33 patients who had EVARs in breach of protocol; ‡five patients per randomised group withdrew consent for being contacted about completing EQ-5D questionnaires but allowed their other data to be used. Completion rates reported indicate fully completed questionnaires

Fig 2 Kaplan-Meier estimates for overall survival by randomised group (log rank P=0.40 for all 613 randomised patients and P=0.19 for 502 patients with confirmed rupture in whom repair was started)

Fig 3 Cumulative incidence of reinterventions in 502 patients in whom repair of rupture was started. Gray’s test for testing equality of cumulative incidence curves: P=0.643 for time to first reintervention; P=0.713 for time to reintervention for life threatening condition (included hindquarter amputation, colectomy with stoma for mesenteric or colonic ischaemia, graft infection, secondary rupture, and repeat aneurysm repairs (full list in table A in appendix 1)

Fig 4 Mean quality of life (EQ-5D score) by randomised group for 502 patients with repair of rupture started, alive and eligible for follow-up at specified time points. Randomisation of critically ill patients needing urgent surgery to avoid death meant that baseline EQ-5D scores were not obtained and set at zero. Average utility scores shown at 3 months and 1 and 3 years. In endovascular strategy versus open repair group mean difference was 0.097 (95% confidence interval 0.031 to 0.163; P=0.004, n=318) at 3 months; 0.068 (0.002 to 0.134; P=0.045, n=301) at 1 year; and 0.013 (−0.069 to 0.096; P=0.751, n=262) at 3 years

Fig 5 Uncertainty in mean cost (£) and QALY differences and their joint distribution for endovascular strategy versus open repair for all 613 patients

Fig 6 Cost effectiveness acceptability curve reporting probability that endovascular strategy is cost effective at alternative levels of willingness to pay (£) for QALY gain