Modified Frailty Index Can Be Used to Predict Adverse Outcomes and Mortality after Lower Extremity Bypass Surgery

Frailty has been increasingly used as a prognostic indicator for various surgical operations. Patients with peripheral arterial disease represent a cohort of population with advanced medical comorbidities. The aim of this study is to correlate the postoperative outcomes after lower extremity bypass surgery with preoperative modified frailty index (mFI).

Using 2010 American College of Surgeons National Surgical Quality Improvement Program database, patients undergoing infrainguinal arterial bypass surgery were identified. mFI with 11 variables, based on the Canadian Study of Health and Aging Frailty Index, was utilized. Based on mFI score, the patients were divided into 4 groups: group 1 (mFI score: 0-0.09), group 2 (mFI score: 0.18-0.27), group 3 (mFI score: 0.36-0.45), and group 4 (mFI score: 0.54-0.63). A bivariate and multivariate analysis was done using logistic regression analysis.

A total of 4,704 patients (64% males and 36% females) underwent infrainguinal arterial bypass. Mean age was 67.9 ± 11.7 years. Distribution of patients based on mFI was as follows: group 1: 14.6%, group 2: 55.9%, group 3: 26.9%, and group 4: 2.6%. Increase in mFI was associated with higher mortality rates. Incidence of mortality for group 1 was 0.6%; for group 2, it was 1.4%; for group 3, it was 4%; and for group 4, it was 7.4%. Likewise, the incidence of other postoperative complications such as myocardial infarction (MI), stroke, progressive renal failure, and graft failure was significantly high among patients with high mFI scores. Following factors were associated with increased risk of mortality: high mFI score, black race, dialysis dependency, postoperative renal insufficiency, MI, and postoperative acute renal failure.

This study demonstrates that the mFI can be used as a valuable tool to identify patients at a higher risk for developing postoperative complications after lower extremity revascularization. For patients with mFI score of 0.54-0.63, the risk of mortality and complications increases significantly. mFI can be used as a useful screening tool to identify patients who are at a high risk for developing complications.