Risk of Lower Extremity Amputation Revision in Patients with Peripheral Vascular Disease Adjusting for a Competing Risk of Death

Abstract

Objectives: The aims of this study are to estimate the cumulative incidence of lower extremity amputation (LEA) revision and reamputation adjusting for a competing risk of death, estimate the one-year event-free mortality rates for patients with peripheral vascular disease undergoing LEA, and develop predictive models for LEA revision and reamputation adjusting for a competing risk of death. Methods: This was a retrospective review of the prospectively collected Vascular Quality Initiative (VQI) registry between 2013 and 2018. Adults undergoing unilateral LEA were included. Demographics, comorbidities, medications, smoking status, history of vascular procedures and revascularization attempts, and procedure urgency were considered. Models to predict LEA revision and reamputation were developed using multivariable regression on the interval-censored competing risks data using semiparametric regression on the cumulative incidence function. Results: The cumulative incidences of LEA revision and revision-free mortality within one year of index amputation are 14.9% and 15.5% respectively. Patient BMI, smoking status, aspirin use, history of revascularization, and level of planned LEA are significantly associated with the odds of LEA revision. Age, amputation urgency, dialysis, and level of planned LEA are associated with the one-year odds of revision-free mortality. A patient receiving an index above knee amputation (AKA) has 61% lower odds of LEA revision (p < 0.0001) but 51% higher odds of revision-free mortality following LEA (p < 0.0001). Previous revascularization procedures increase the odds of revision by 23% (p < 0.0001). The cumulative incidences of reamputation and one-year reamputation-free mortality following LEA are 11.5% and 16.9% respectively. Urgency of the procedure, history of revascularization procedures, and level of planned LEA are statistically associated with the odds of reamputation when adjusting for the competing risk of death. Patients receiving index AKA have 62% lower odds of reamputation (p < 0.0001) compared to BKA. Dialysis is the strongest predictor of one-year mortality (OR 2.576, p < 0.0001). Conclusions: Patients with appropriately managed PVD, which still progresses to amputation have higher odds of LEA revision and reamputation. Revision risk can be predicted and compared on the basis of patient factors and the planned index amputation.