Long-term mortality after lower-limb amputation

Background: Mortality after amputation is known to be extremely high and is associated with a number of patient features. We wished to calculate this mortality after first-time lower-limb amputation and investigate whether any population or treatment factors are associated with worse mortality. Objective: To follow up individuals after lower limb amputation and ascertain the mortality rate as well as population or treatment features associated with mortality. Study design: A prospective cohort study. Methods: Prospective lower-limb amputations over 1year (N=105) at a Regional Rehabilitation Centre were followed up for 3years. Results: After 3years, 35 individuals in the cohort had died, representing a mortality of 33%. On initial univariate analysis, those who died were more likely to have diabetes mellitus ((2)=7.16, df=1, p=0.007) and less likely to have been fitted with a prosthesis ((2)=5.84, df=1, p=0.016). There was no association with age, gender, level of amputation, social isolation, significant medical co-morbidity other than diabetes or presence of mood disorders. A multi-variable logistic regression (backward step) confirmed that diabetes (odds ratio=3.04, confidence intervals=1.25-7.40, p=0.014) and absence of prosthesis-fitting (odds ratio=2.60, confidence interval=1.16-6.25, p=0.028) were independent predictors of mortality. Conclusion: Mortality after amputation is extremely high and is increased in individuals with diabetes or in those who are not fitted with a prosthesis after amputation. Clinical relevance The link between diabetes and mortality after amputation has been noted by others, but this is the first study to find an effect from prosthetic limb-wearing. This requires further investigation to ascertain why the wearing of a prosthetic limb, confers an independent survival benefit that is not related to the presence of medical co-morbidity.