Risk Factors for Development of Incisional Hernia after Aortic Aneurysm Repair: Secondary Analysis of the OVER Randomized Controlled Trial

Abstract

Since the risk of mortality from rupture is elevated, elective repair of abdominal aortic aneurysms (AAA) is often recommended. Currently, over 80% of elective repairs are carried out using an endovascular approach. While open repair has similar late survival and fewer reintervention outcomes when compared to endovascular repair, incisional hernia is a frequent complication with morbidity and cost implications. The Open Versus Endovascular Repair (OVER) trial was the largest randomized trial of endovascular versus open repair of abdominal aortic aneurysms in the United States. The purpose of this study was to determine risk factors associated with incisional hernia development following AAA repair via secondary analysis of the OVER data. This was a multi-site trial conducted within the Veterans Affairs healthcare system. Study participants (N=881) were enrolled from 2002-2008 and followed until 2011 with additional administrative data collection until 2016. Eligible patients had abdominal aortic aneurysms for which elective repair was planned and randomized 1:1 to either open or endovascular repair. Incisional hernia was a prespecified endpoint in the OVER protocol, specifically assessed at each protocol follow up visit. Technical details were extracted from each operative report, repair case report form(s), and adverse event form(s). Patient demographics, comorbid conditions, reported preoperative activity level, and operative details including initial approach, blood loss, and closure methods were analyzed using Bayesian hierarchical Weibull survival regression modeling. Incisional hernias were recorded among 46 participants (5.2%). The average time to hernia diagnosis was 3.5 years. Of the 437 participants randomized to open treatment, 427 received an open repair including crossovers from endovascular treatment assignment. Transperitoneal repair was performed in 81%, running suture in 96%, and absorbable suture in 71% of cases. Randomization to endovascular repair was associated with reduced risk of hernia (HR 0.70, 95% CI 0.49-0.94). Higher activity level was associated with increased hernia risk (HR 1.39, 95% CI 1.06-1.84). Approach, suture closure techniques, BMI, diabetes, and smoking status were not associated with increased risk of hernia development. Incisional hernia is a frequent complication associated with open repair of abdominal aortic aneurysm and commonly required reintervention. Endovascular repair was associated with reduced risk of hernia. Patients with increased activity experienced a higher incidence of hernia. However, no other modifiable patient, operative, or technical factors were found to be associated with hernia development.