Ethnicity and risk of lower limb amputation in people with Type 2 diabetes: a prospective cohort study

Lower limb amputation is a serious complication of diabetic foot disease and there are unexplained ethnic variations in incidence. This study investigates the risk of amputation among different ethnic groups after adjusting for demographic, socio-economic status and clinical variables.

We used primary care data from a large national multi-ethnic cohort of patients with Type 2 diabetes in New Zealand and linked hospital records. The primary outcome was time from initial data collection to first lower limb amputation. Demographic variables included age of onset and duration since diabetes diagnosis, gender, ethnicity and socio-economic status. Clinical variables included smoking status, height and weight, blood pressure, HbA1c , total cholesterol/HDL ratio and albuminuria. Cox proportional hazards models were used.

There were 892 lower limb amputations recorded among 62 002 patients (2.11 amputations per 1000 person-years), followed for a median of 7.14 years (422 357 person-years). After adjusting for demographic and socio-economic variables and compared with Europeans, Māori had the highest risk [hazard ratio (HR) 1.84 (95%CI:1.54-2.19)], whereas East Asians [HR 0.18, (0.08-0.44)] and South Asians [HR 0.39 (0.22-0.67)] had the lowest risk. Adjusting for available clinical variables reduced the differences but they remained substantial [HR 1.61 (1.35-1.93), 0.23 (0.10-0.56) and 0.48 (0.27-0.83), respectively].

Ethnic groups had significantly different risk of lower limb amputation, even after adjusting for demographic and some major clinical risk factors. Barriers to care should be addressed and intensive prevention strategies known to reduce the incidence of lower limb amputations could be prioritized to those at greatest risk.