Incidence and predictors of diabetic foot ulcer among patients with diabetes mellitus in a diabetic follow-up clinic in Central Ethiopia: a retrospective follow-up study

Background Diabetic foot ulcer is a major medical, social, and economic problem, and a leading cause of hospitalisations, increased morbidity, and mortality. Despite a rising occurrence, there is a dearth of data on the incidence and its predictors. Objective To assess the incidence and predictors of diabetic foot ulcers among patients with diabetes mellitus in a diabetic follow-up clinic in Central Ethiopia. Design Retrospective follow-up study design. Participants A total of 418 newly diagnosed diabetes mellitus patients from 1 January 2012 to 31 December 2022. A computer-generated simple random sampling method was used to select the study participants. Data were collected using a structured data extraction checklist. The collected data were entered into Epi Info V.7.2 and exported to STATA V.14 for analysis. To estimate survival time, the Kaplan-Meier method was used, and the survival difference was tested using a log-rank test. Outcome measures The Cox proportional hazard model was fitted to identify the predictors of diabetic foot ulcer development. The strength of the association was estimated using an adjusted hazard ratio (AHR) with a 95% confidence interval (CI), and statistical significance was proclaimed at a p<0.05. Result The overall incidence of diabetic foot ulcer was 1.51 cases (95% CI 1.03 to 2.22) per 100 person-years of observation. The cumulative incidence was 6.2% (95% CI 4.1% to 8.6%) over 10 years. The median time of follow-up was 45 months (IQR 21-73). Diastolic blood pressure of 90 mm Hg or above (AHR 2.91, 95% CI 1.25 to 6.77), taking combined medication (AHR 3.24, 95% CI 1.14 to 9.19) and having a peripheral arterial disease (AHR 5.26, 95% CI 1.61 to 17.18) were statistically significant predictors of diabetic foot ulcer development. Conclusion The risk of occurrence of diabetic foot ulcer was relatively high. Diastolic blood pressure level, combined medication and peripheral arterial disease were independent predictors of diabetic foot ulcer development. Hence, close monitoring and proper interventions are essential.