Patient fitness and survival after abdominal aortic aneurysm repair in patients from the UK EVAR trials

Background: The aim was to use a validated fitness score to determine whether fitter patients with a large abdominal aortic aneurysm (AAA) benefited from having open rather than endovascular repair. Methods: The Customized Probability Index (CPI) was applied to patients in the Endovascular Aneurysm Repair (EVAR) I and II trials. Interaction tests between CPI and randomized group assessed the effect of fitness and type of AAA repair on elective 30-day mortality and 4-year survival. Results: The mean(s.d.) CPI scores were 3.6(9.3) for 1252 EVAR I patients and 10.0(11.3) for 404 EVAR H patients (range -25 to +43) (P<0.001). The fitness of EVAR I patients was classified as good (579 patients, mean CPI -4.2), moderate (331 patients, mean CPI 5.7) or poor (338 patients, mean CPI 15.1). Only in the good fitness group did 30-day mortality convincingly favour endovascular repair (odds ratio 0.24, P=0.030), but overall the test of interaction was not significant (P=0.363). For 4-year all-cause and aneurysm-related mortality, there was no benefit for either treatment across all fitness scores (P=0.281 and P=0.371 respectively). Conclusion: The benefit of endovascular repair was most convincing in the fittest patients. There was no evidence that the fittest patients benefited more from open surgery.