Comparison of Unibody and Non-Unibody Endografts for Abdominal Aortic Aneurysm Repair in Medicare Beneficiaries: The SAFE-AAA Study.

BACKGROUND

Concerns have been raised about the long-term performance of aortic stent grafts for the treatment of abdominal aortic aneurysms, in particular, unibody stent grafts (eg, Endologix AFX AAA stent grafts). Only limited data sets are available to evaluate the long-term risks related to these devices. The SAFE-AAA Study (Comparison of Unibody and Non-Unibody Endografts for Abdominal Aortic Aneurysm Repair in Medicare Beneficiaries Study) was designed with the Food and Drug Administration to provide a longitudinal assessment of the safety of unibody aortic stent grafts among Medicare beneficiaries.

METHODS

The SAFE-AAA Study was a prespecified, retrospective cohort study evaluating whether unibody aortic stent grafts are noninferior to non-unibody aortic stent grafts with respect to the composite primary outcome of aortic reintervention, rupture, and mortality. Procedures were evaluated from August 1, 2011, through December 31, 2017. The primary end point was evaluated through December 31, 2019. Inverse probability weighting was used to account for imbalances in observed characteristics. Sensitivity analyses were used to evaluate the effect of unmeasured confounding, including assessment of the falsification end points heart failure, stroke, and pneumonia. A prespecified subgroup included patients treated from February 22, 2016, through December 31, 2017, corresponding to the market release of the most contemporary unibody aortic stent grafts (Endologix AFX2 AAA stent graft).

RESULTS

Of 87 163 patients who underwent aortic stent grafting at 2146 US hospitals, 11 903 (13.7%) received a unibody device. The average age of the total cohort was 77.0±6.7 years, 21.1% were female, 93.5% were White, 90.8% had hypertension, and 35.8% used tobacco. The primary end point occurred in 73.4% of unibody device-treated patients versus 65.0% of non-unibody device-treated patients (hazard ratio, 1.19 [95% CI, 1.15-1.22]; noninferior value of 1.00; median follow-up, 3.4 years). Falsification end points were negligibly different between groups. In the subgroup treated with contemporary unibody aortic stent grafts, the cumulative incidence of the primary end point occurred in 37.5% of unibody device-treated patients and 32.7% of non-unibody device-treated patients (hazard ratio, 1.06 [95% CI, 0.98-1.14]).

CONCLUSIONS

In the SAFE-AAA Study, unibody aortic stent grafts failed to meet noninferiority compared with non-unibody aortic stent grafts with respect to aortic reintervention, rupture, and mortality. These data support the urgency of instituting a prospective longitudinal surveillance program for monitoring safety events related to aortic stent grafts.