Three-Year IMPROVE Results Compare Treatment Strategies for Ruptured AAA
November 16, 2017—Three-year results from the IMPROVE trial comparing strategies to treat ruptured abdominal aortic aneurysms (rAAAs) were published online in BMJ by Professor Janet T. Powell, MD, on behalf of the IMPROVE trial investigators (2017;359:j4859). The objective of the trial was to assess the 3-year clinical outcomes and cost-effectiveness of a strategy of endovascular repair (aortic morphology if suitable, open repair if not) versus open repair for patients with suspected rAAA. Prof. Powell presented the IMPROVE data at the VEITHsymposium held November 14–18 in New York, New York.
As summarized in BMJ, the randomized controlled trial enrolled patients at 30 vascular centers (29 in the United Kingdom and one in Canada) from 2009 to 2016. The study included 613 eligible patients (480 men) with a clinical diagnosis of ruptured aneurysm, of whom 502 underwent emergency repair for rupture. There were 316 patients randomized to an endovascular strategy (275 with confirmed rupture) and 297 to open repair (261 with confirmed rupture).
The main outcome measure was mortality. Secondary measures were reinterventions after aneurysm repair, quality of life, and hospital costs to 3 years.
The investigators reported that the maximum follow-up for mortality was 7.1 years; two patients in each group were lost to follow-up by 3 years. After similar mortality by 90 days, in the midterm (3 months to 3 years), there were fewer deaths in the endovascular group than the open repair group (hazard ratio [HR], 0.57; 95% confidence interval [CI], 0.36–0.90), leading to lower mortality at 3 years (48% vs 56%). By 7 years, mortality was approximately 60% in each group (HR, 0.92; 95% CI, 0.75–1.13).
The study found that results for the 502 patients with repaired ruptures were more pronounced. The 3-year mortality was lower in the endovascular strategy group (42% vs 54%; odds ratio, 0.62; 95% CI, 0.43–0.88), but after 7 years, there was no clear difference between the groups (HR, 0.86; 95% CI, 0.68–1.08).
Reintervention rates up to 3 years were not significantly different between the randomized groups (HR, 1.02; 95% CI, 0.79–1.32); the initial rapid rate of reinterventions was followed by a much slower midterm reintervention rate in both groups. The early higher average quality of life in the endovascular strategy group versus open repair group, coupled with the lower mortality at 3 years, led to a gain in average quality-adjusted life years (QALYs) at 3 years of 0.17 (95% CI, 0–0.33).
The endovascular strategy group spent fewer days in the hospital and had lower average costs of −£2,605 (95% CI, −£5,966–£702)—approximately €2,813 and $3,439. The probability that the endovascular strategy is cost-effective was > 90% at all levels of willingness to pay for a QALY gain.
The IMPROVE investigators concluded that at 3 years, compared with open repair, an endovascular strategy for suspected rAAA was associated with a survival advantage, a gain in QALYs, similar levels of reintervention, and reduced costs. Additionally, an endovascular strategy was cost-effective. These findings support the increasing use of an endovascular strategy with wider availability of emergency endovascular repair, advised the investigators in BMJ.
In commentary to Endovascular Today, Prof. Powell stated, "This is the only one of the randomized trials of endovascular versus open repair for rAAA with comprehensive midterm follow-up and underscores the value of this longer-term follow-up. We hope that the IMPROVE evidence will persuade policy makers that the endovascular strategy is the correct one for ruptured aneurysms. However, clinicians should be aware that endovascular repair should only be used in reasonably suitable aortic anatomy (otherwise the mortality rises sharply), and therefore, skills in emergency open repair need to be maintained."
Prof. Powell continued, "Also of interest is that in IMPROVE, endovascular repair procedures used mainly bifurcated endografts and we did not see the high rate of infected grafts as reported by the AJAX trial, which used mainly aorto-uni-iliac devices. We hope to publish full details of reinterventions after ruptured aneurysm repair in the near future."