Lower-extremity amputation as a marker for renal and cardiovascular events and mortality in patients with long standing type 1 diabetes

BACKGROUND We evaluated the risks of renal and cardiovascular complications, and mortality associated with lower extremity amputation (LEA) in patients with type 1 diabetes. METHODS We studied two cohorts of people with long standing type 1 diabetes: GENEDIAB (n = 456) and GENESIS (n = 611). Subsets of the cohorts (n = 260, n = 544) were followed for 9 and 5 years, respectively. Outcomes were the incidence of end stage renal disease (ESRD), myocardial infarction, stroke and mortality during follow-up. Analyses were performed in pooled cohorts. RESULTS The prevalence of LEA at baseline was 9.3 % (n = 99). A positive history of LEA was associated with the baseline prevalence of established (OR 4.50, 95 % CI 2.33-8.91, p < 0.0001) and advanced diabetic nephropathy (OR 5.50, 95 % CI 2.89-10.78, p < 0.0001), ESRD (OR 2.86, 95 % CI 1.43-5.50, p = 0.004), myocardial infarction (OR 3.25, 95 % CI 1.68-6.15, p = 0.0006) and stroke (OR 3.88, 95 % CI 1.67-8.72, p = 0.002, adjusted for sex, age, and cohort membership). A positive history of LEA at baseline was associated with the incidence during follow-up of ESRD (HR 2.69, 95 % CI 1.17-6.20, p = 0.02), and myocardial infarction (HR 3.53, 95 % CI 1.79-6.97, p = 0.0001). History of LEA was also associated with increased risk for all-cause (HR 3.55, 95 % CI 2.05-6.16, p < 0.0001), cardiovascular (HR 3.30, 95 % CI 1.36-8.02, p = 0.008), infectious disease (HR 5.18, 95 % CI 1.13-23.84, p = 0.03) and other-cause mortality (HR 2.81, 95 % CI 1.09-7.26, p = 0.03). History of LEA at baseline was associated with a 40 % reduction in the duration of survival in the subset of patients who died during follow-up. Population attributable risk of the history of LEA at baseline for total mortality during follow-up was 0.31. CONCLUSIONS Patients with LEA have a higher risk of ESRD, myocardial infarction and cardiovascular and non-cardiovascular mortality. Our results highlight the importance of LEA as a key-predictor for major vascular events and premature death in type 1 diabetic patients.