Mortality and survival rates following lower limb amputation: a national observational cohort study in Sweden

Abstract To compare the association between initial lower limb amputation (LLA) and mortality risk compared with matched controls, and to determine whether this association varies by amputation level and by region of residence by comparing individuals with and without LLA within each region. We also assessed temporal trends in 1-year post-amputation mortality. This matched cohort study used population-based national registers in Sweden to identify initial LLAs performed from 2008 to 2017. Individual with LLA was matched by age-, sex-, and county with up to 10 individuals without an LLA. Cox proportional hazards regression was used to estimate hazard ratios (HRs). A total of 16,757 people with LLA and 165,555 without LLA were included, of whom 76.1% and 37.6%, respectively, died during follow-up (until December 31, 2018). LLA was associated with a 4.48-fold higher mortality risk (95% CI 4.39–4.57), after adjusting for age, sex, marital status, education, and birth in Sweden (yes/no). HRs for specific amputation levels were 5.19 (5.05–5.33) for high proximal, 4.05 (3.94–4.16) for low proximal, and 3.93 (3.69–4.19) for partial foot amputations. LLA was associated with higher mortality compared with individuals without LLA within each of Sweden’s 21 regions, HRs ranged from 3.67 (CI 3.26–4.12) in Kalmar to 5.16 (CI 4.56–5.83) in Södermanland. The association varied significantly by regions (global test of interaction, p < 0.001). One-year mortality remained largely stable during the study period, although a small declining trend was observed following high proximal amputation (mortality rate ratio 0.986, 95% CI 0.972–0.999). Lower limb amputation was strongly associated with increased mortality compared with matched individuals without LLA, with poorer survival following more proximal amputation. The association was observed across all Swedish regions, although its magnitude varied significantly between regions. One-year mortality remained largely stable between 2008 and 2017, with a small declining trend following high proximal amputation. Exploratory analyses identified chronic kidney disease and heart failure among the comorbidities associated with increased mortality. These findings highlight the substantial mortality and systemic disease burden among individuals undergoing LLA.