Predictive factors for lower extremity amputations in patients with diabetic foot disease in Central Australia

Abstract

Background: Lower extremity amputation (LEA) is a common outcome of diabetic foot disease (DFD) among First Nations Australians; however, data from Central Australia are limited. We therefore identified risk factors for progression to LEA for First Nations Australians at Alice Springs Hospital (ASH). Methods: All adults with DFD admitted between 2015 and 2020 were included in a retrospective cohort study. Patients were identified using International Classification of Diseases, 10th Revision codes for DFD and amputation. A logistic regression and Cox regression model was used to identify risk factors for amputation and mortality respectively. Results: Three hundred eight adults (86% First Nations people) were admitted for management of DFD, of whom 116 (37.7%) patients underwent at least one amputation, 20.7% had more than one amputation performed and 23.7% required amputation during their index admission. In a multivariable logistic regression model, osteomyelitis was the strongest predictor for amputation (OR 14.58, 95% CI 7.17–31.41, P < 0.001). Involvement of podiatry reduced the risk of amputation (OR 0.29, 95% CI 0.12–0.63, P 0.002). Amputation conferred no mortality benefit (HR 1.13, 95% CI 0.71–1.79, P 0.61). Methicillin-resistant Staphylococcus aureus (MRSA) was the most common pathogen identified (no LEA, 17%; LEA, 28%). Pseudomonas spp. (4.4%) and resistant gram negatives (1.9%) were uncommon. Conclusion: LEA was a common outcome for First Nations patients who presented with DFD in Central Australia. Multidisciplinary care that includes podiatry and improved diabetes management is essential to reduce amputation rates. Empiric treatment of DFD in Central Australia should include MRSA coverage.