Age and sex may significantly interact with diabetes on the risks of lower-extremity amputation and peripheral revascularization procedures: Evidence from a cohort of a half-million diabetic patients

OBJECTIVE - Using the National Health Insurance claim data, we prospectively investigated the age- and sex-specific incidence density and relative hazards of nontraumatic lower-extremity amputation (LEA) and peripheral revascularization procedure (PRP) of the diabetic population in Taiwan. RESEARCH DESIGN AND METHODS - A total of 500,868 diabetic patients and 500,248 age- and sex-matched control subjects, selected from the ambulatory care claim (1997) and the registry for beneficiaries, respectively, were linked to inpatient claims (1997-2002) to identify hospitalizations due to nontraumatic LEA and PRP. Incidence density was calculated under the Poisson assumption, and the Kaplan-Meier analysis was used to assess the cumulative event rates over a 6-year follow-up period. We also evaluated the age- and sex-specific relative hazards of nontraumatic LEA and PRP in relation to diabetes with Cox proportional hazard regression model adjusted for demographics and regional areas. RESULTS - The estimated incidence density of nontraumatic LEA and PRP for diabetic men was 410.3 and 317.0 per 100,000 patient-years, respectively. The corresponding data for diabetic women were relatively low at 115.2 and 86.0 per 100,000 patient-years. Compared with control subjects with the same age and sex, diabetic patients consistently suffered from significantly elevated relative hazards of nontraumatic LEA. Young and female patients were especially vulnerable to experience increased risks of nontraumatic LEA, but such effect modification by age and sex was less apparent for PRP. CONCLUSIONS - Multidisciplinary diabetes foot care systems, including the provision of revascularization procedures, should be further enforced to reduce subsequent risks of nontraumatic LEA, especially in young and female diabetic patients.