Risks of nontraumatic lower-extremity amputations in patients with type 1 diabetes -: A population-based cohort study in Sweden

OBJECTIVE - The purpose of this study was to estimate the risks of nontraumatic lower-extremity amputations (LEAS) in patients With type 1 diabetes. RESEARCH DESIGN AND METHODS - We identified 31,354 patients with type 1 diabetes (15,001 women and 16,353 men) in the Swedish Inpatient Register between 1975 and 2004. The incidence of nontraumatic LEAs was followed up until 31 December 2004 by cross-linkage in the Inpatient Register and linkage to the Death and Migration registers. Poisson regression modeling was used to compare the risks of nontraumatic LEAs during different calendar periods of follow-up, with adjustment for both sex and attained age at follow-up. Standardized incidence ratios (SIRs) were used to estimate the relative risks (RRs) with the age-, sex-, and calendar period-matched general Swedish population as reference. The cumulative probability of nontraumatic LEAs was calculated by the Kaplan-Meier method. RESULTS - In total, 465 patients with type 1 diabetes undenwent nontraumatic LEAS. The risk was lower during the most recent calendar period (2000-2004) than during the period before 2000 (RR 0.6 [95% CI 0.5-0.8]). However, even in this most recent period, the risk for nontraumatic LEAs among these relatively young patients was 86-fold higher than that in the matched general population (SIR 85.8 [72.9-100.3]). By age 65 years, the cumulative probability of having a nontraumatic LEA was 11.0% for women with type 1 diabetes and 20.7% for men with type 1 diabetes. CONCLUSIONS - Although the risks appeared to have declined in recent years, patients with type 1 diabetes still have a very high risk for nontraumatic LEAs.