Prevalence and Risk Factors for Diabetic Lower Limb Amputation: A Clinic-Based Case Control Study

Objective. The aim of the study was to evaluate the prevalence of and risk factors for lower limb amputation in a specialist foot clinic-based setting. Methods. A retrospective quantitative study was conducted, using clinical and biochemical profiles of diabetic foot patients attending the High Risk Foot Clinic at The Townsville Hospital, Australia, between January 1, 2011, and December 31, 2013. Results. The total study sample included 129 subjects, comprising 81 males and 48 females with M : F ratio of 1.7 : 1. Twenty-three subjects were Indigenous Australians, representing 17.8% of the study population. The average age of the cohort was 63.4 years ± 14.1 years [CI 90.98-65.89]. Lower limb amputation was identified as a common and significant outcome (n = 44), occurring in 34.1%, more commonly amongst the Indigenous Australians (56.5% versus 29.2%; p = 0.94, OR 0.94). Risk factors most closely associated with amputation included diabetic retinopathy (p = 0.00, OR 4.4), coronary artery bypass graft (CABG) surgery (p = 0.01, OR 4.1), Charcot's arthropathy (p = 0.01, OR 2.9), and Indigenous ethnicity (p = 0.01, OR 3.4). Although average serum creatinine, corrected calcium, and glycosylated haemoglobin A1c (Hba1c) levels were higher amongst amputees they were statistically insignificant. Conclusions. Lower limb amputation is a common outcome and linked to ethnicity and neurovascular diabetic complications amongst subjects with diabetic foot ulcer. Further research is needed to identify why risk of lower limb amputation seems to differ according to ethnicity.