Comparison of major adverse event rates after elective endovascular aneurysm repair in New England using a novel measure of complication severity

Abstract

Objective: Major adverse event (MAE) rates are used as an outcome measure after surgical procedures. Although MAE rates summarize the occurrences of adverse events, they do not reflect differences in severity of these events. We propose that a measure of complication severity could provide a more accurate assessment about the quality of care. We aimed to analyze and to describe the regional variation in elective endovascular aneurysm repair (EVAR) MAE rates across centers in the Vascular Study Group of New England and to create an index for describing complication severity.

Methods: Patients undergoing elective EVAR (n = 4731) at 30 Vascular Study Group of New England centers between 2003 and 2016 were studied. The MAE composite end point was defined as the occurrence of any of the following postoperative events: myocardial infarction, dysrhythmia, congestive heart failure, leg ischemia, renal insufficiency, bowel complication, reoperation, surgical site infection, stroke, respiratory complication, and no home discharge. An adjustment factor (complication severity index) was calculated as a ratio of length of stay for complicated to uncomplicated cases. Multivariate logistic regression was used to calculate predicted MAE rates. The observed and predicted MAE rates as well as complication severity index rates were compared among centers and across quintiles of center volume.

Results: Observed MAE rates varied widely, ranging from 0% to 39%. Multivariate predictors of MAE included abdominal aortic aneurysm diameter >6 cm (odds ratio [OR], 2.1; 95% confidence interval [CI], 2.0-2.3), female sex (OR, 2.0; 95% CI, 1.8-2.2), chronic renal insufficiency (OR, 1.9; 95% CI, 1.7-2.1), age >75 years (OR, 1.9; 95% CI, 1.8-2.1), congestive heart failure (OR, 1.7; 95% CI, 1.5-1.9), chronic obstructive pulmonary disease (OR, 1.5; 95% CI, 1.4-1.6), diabetes (OR, 1.4; 95% CI, 1.1-1.7), positive stress test result (OR, 1.2; 95% CI, 1.1-1.4), preoperative beta blocker (OR, 1.2; 95% CI, 1.1-1.3), and no preoperative statin (OR, 1.2; 95% CI, 1.1-1.3). Predicted MAE rates had little variation (range, 21%-29%). In comparing observed MAE rates and complication severity, there was an inverse relation between the two, suggesting that although certain centers had a greater number of MAEs, the complications were less severe.

Conclusions: MAE rates after elective EVAR vary widely. However, centers with higher MAE rates tended to have less severe complications, suggesting that observed MAE rates may not be a good measure of outcomes assessment after elective EVARs.

Keywords: Abdominal aortic aneurysm (AAA); Endovascular aneurysm repair (EVAR); Major adverse events (MAEs).