Modified Frailty Index as a Predictor of Contralateral Amputation and Mortality After Primary Amputation in Patients With Critical Limb Ischemia

Abstract

Background

Critical limb ischemia (CLI) is an advanced stage of peripheral arterial disease (PAD) often requiring major amputation. Frailty influences surgical outcomes but remains underexplored in CLI. This study evaluates the 5-item Modified Frailty Index (mFI-5) as a predictor of 1-year mortality and contralateral amputation following major amputation for CLI.

Materials and Methods

A retrospective analysis was conducted on 327 patients who underwent primary above- or below-knee amputation (AKA or BKA) for CLI. Patients were stratified into 2 groups based on frailty: mFI-5 <3 (less frail) and mFI-5 ≥3 (severely frail). Binomial logistic regression was used to assess associations between frailty and outcomes, with significance set at P < .05.

Results

When analyzed as a continuous variable, mFI-5 did not significantly predict 1-year mortality or contralateral amputation (P = .059, .693). When stratified by frailty status, severe frailty (mFI-5 ≥3) was associated with increased odds of 1-year mortality (OR 1.815, P = .030). Among patients undergoing index AKA, severely frail individuals had the highest risk of mortality (OR 2.67; 95% CI 1.52-4.78; P < .001). Contralateral amputation was also linked to increased 1-year mortality compared to similarly frail patients without a second amputation (P = .010).

Conclusion

Severe frailty is associated with worse outcomes, particularly 1-year mortality, following amputation for CLI. While frailty did not independently predict contralateral amputation, its occurrence was linked to increased mortality in frail patients. These findings support incorporating frailty assessment into CLI surgical decision-making and postoperative care.