Effects of Ethnicity and Nephropathy on Lower-Extremity Amputation Risk Among Diabetic Veterans

Abstract

OBJECTIVE—To describe ethnic differences in the risk of amputation in diabetic patients with diabetic nephropathy. RESEARCH DESIGN AND METHODS—A retrospective cohort study was conducted on a national cohort of diabetic patients who received primary care within the Veterans Affairs (VA) Health Care System. Hospitalizations for lower-limb amputations were established by ICD-9-CM procedure codes. Relative risk of amputation in diabetic patients with and without diabetic nephropathy was determined using Cox proportional hazard modeling for unadjusted and adjusted models. RESULTS—Of the 429,918 subjects identified with diabetes (mean age 64 ± 11 years, 97.4% male), 3,289 individuals were determined to have had a lower-limb amputation during the study period. Compared with diabetic patients without amputations, amputees were on average older, more likely to belong to a minority group, and were more likely to have received treatment for more comorbid conditions. Asians were more likely to have toe amputations compared with whites or other ethnicities, while Native Americans were more likely to have below-the-knee amputations. Native Americans had the highest risk of amputation (RR 1.74, 95% CI 1.39–2.18), followed by African Americans (RR 1.41, 95% CI 1.34–1.48) and Hispanics (RR 1.28, 95% CI 1.20–1.38) compared with whites. The presence of diabetic nephropathy increased the risk of amputation threefold in all groups. Asian subjects with diabetes had the lowest adjusted relative risk of amputation (RR 0.31, 95% CI 0.19–0.50). CONCLUSIONS—Among diabetic patients, certain ethnic minority individuals have an increased risk of lower-extremity amputation compared with whites. Presence of diabetic nephropathy further increases this risk.