Individual-patient meta-analysis of three randomized trials comparing endovascular versus open repair for ruptured abdominal aortic aneurysm

Abstract

Background: The benefits of endovascular repair of ruptured abdominal aortic aneurysm remain controversial, without any strong evidence about advantages in specific subgroups.

Methods: An individual-patient data meta-analysis of three recent randomized trials of endovascular versus open repair of abdominal aortic aneurysm was conducted according to a prespecified analysis plan, reporting on results to 90 days after the index event.

Results: The trials included a total of 836 patients. The mortality rate across the three trials was 31.3 per cent for patients randomized to endovascular repair/strategy and 34.0 per cent for those randomized to open repair at 30 days (pooled odds ratio 0.88, 95 per cent c.i. 0.66 to 1.18), and 34.3 and 38.0 per cent respectively at 90 days (pooled odds ratio 0.85, 0.64 to 1.13). There was no evidence of significant heterogeneity in the odds ratios between trials. Mean(s.d.) aneurysm diameter was 8.2(1.9) cm and the overall in-hospital mortality rate was 34.8 per cent. There was no significant effect modification with age or Hardman index, but there was indication of an early benefit from an endovascular strategy for women. Discharge from the primary hospital was faster after endovascular repair (hazard ratio 1.24, 95 per cent c.i. 1.04 to 1.47). For open repair, 30-day mortality diminished with increasing aneurysm neck length (adjusted odds ratio 0.69 (95 per cent c.i. 0.53 to 0.89) per 15 mm), but aortic diameter was not associated with mortality for either type of repair.

Conclusion: Survival to 90 days following an endovascular or open repair strategy is similar for all patients and for the restricted population anatomically suitable for endovascular repair. Women may benefit more from an endovascular strategy than men and patients are, on average, discharged sooner after endovascular repair.

Figure 1

Kaplan–Meier survival plots up to 90 days by trial and randomized group: a AJAX, b ECAR, c IMPROVE and d patients with ruptured abdominal aortic aneurysm (rAAA) suitable for endovascular repair (EVAR) in IMPROVE. a P = 0·866, b P = 0·048, c P = 0·899, d P = 0·890 (log rank test)

Figure 2

Analysis of 90‐day mortality by randomized group: a all patients and b patients with ruptured abdominal aortic aneurysm (rAAA) eligible for both endovascular aneurysm repair (EVAR) and open repair. Odds ratios are shown with 95 per cent c.i.

Figure 3

Analysis of 90‐day mortality by randomized group with subgroup analyses for age, sex and Hardman index. Multiple imputation was used for Hardman index. With small numbers in the ECAR trial (2 of 9 deaths within 90 days in women), the trial‐specific subgroup effect for sex was calculated by adding a continuity correction of 0·5 to all cells in the contingency table. Ratios of odds ratios are shown with 95 per cent c.i. EVAR, endovascular aneurysm repair

Figure 4

Hazard ratios, with 95 per cent c.i., for time to discharge alive from primary admission hospital by randomized group. EVAR, endovascular aneurysm repair

Figure 5

Effect of aneurysm neck length on 30‐day mortality, by treatment commenced. The analysis was restricted to patients with ruptured abdominal aortic aneurysm who underwent CT, commenced treatment and did not have a common iliac aneurysm. All analyses were adjusted for age, sex, Hardman index, admission mean arterial BP, treatment commenced and randomized group. Multiple imputation was used to account for missing data. Odds ratios of 30‐day mortality per 15‐mm increase in aneurysm neck length are shown with 95 per cent c.i. EVAR, endovascular aneurysm repair