Factors influencing short- and long-term mortality after lower limb amputation

Abstract

Mortality after lower limb amputation is high, with UK 30-day mortality rates of 9-17%. We performed a retrospective analysis of factors affecting early and late outcome after lower limb amputation for peripheral vascular disease or diabetic complications at a UK tertiary referral vascular centre between 2003 and 2010. Three hundred and thirty-nine patients (233 male), of median (IQR [range]) age 73 (62-79 [26-92]) years underwent amputation. Thirty-day mortality was 12.4%. On regression modelling, the risk of 30-day mortality was increased in patients of ASA grade ≥ 4 (OR 4.23, 95% CI 2.07-8.63), p < 0.001 and age between 74 and 79 years (OR 3.8, 95% CI 1.10-13.13), p = 0.04 and older than 79 years (OR 4.08, 95% CI 1.25-13.25), p = 0.02. Peri-operative (30-day) mortality for these groups was 23.2%, 13.7% and 18.8%, respectively. Survival and Cox regression analysis demonstrated that long-term mortality was associated with: age 74-79 years (HR 2.15, 95% CI 1.38-3.35), p = 0.001; age > 79 years (HR 2.78, 95% CI 1.82-4.25), p < 0.001; ASA grade ≥ 4 (HR 2.04, 95% CI 1.51-2.75), p < 0.001; out-of-hours operating (HR 1.51, 95% CI 1.08-2.10), p = 0.02; and chronic kidney disease stage 4-5 (1.57, 95% CI 1.07-2.30), p = 0.02. Anaesthetic technique was associated with long-term mortality on survival analysis (p = 0.04), but not when analysed using regression modelling. Mortality after lower limb amputation relates to patient age, ASA, out-of-hours surgery and renal dysfunction. These data support lower limb amputations' being performed during daytime hours and after modification replace with 'of ' correctable risk factors.