Incidence of Diabetic Retinopathy and Its Predictors Among Newly Diagnosed Type 1 and Type 2 Diabetic Patients: A Retrospective Follow-up Study at Tertiary Health-care Setting of Ethiopia

BACKGROUND: With an increasing number of diabetes patients in developing countries, the burden of diabetes-related blindness is undoubtedly posing a massive challenge to the sustainable health care system due to the cost of care. Despite this fact, to date, most of the epidemiological research on diabetic retinopathy (DR) in eastern Africa, including Ethiopia, has been limited to survey studies. Thus, we determined the incidence of retinopathy and its predictors among diabetic patients in Jimma University Medical Center, Southwest Ethiopia. METHODS: A retrospective follow-up study was conducted on 402 randomly selected diabetic patients of aged ≥15 years. A preliminary reviewed checklist was used to obtain information on the demographics, clinical and physiological attributes. Data were entered using EpiData version 4.6 and analyzed using Stata version 14. All variables at P-values less than 0.2 in bivariable analysis were exported to multivariable analysis. Multivariable accelerated failure time (AFT) regression analyses using Weibull distribution were used to examine the predictors of DR at a 5% level of significance. RESULTS: Throughout a median follow-up period of 5.9 years, the cumulative incidence of DR was 20.15% (95%CI: 16.50–24.37) and the incidence rate was 36.9 per 1000 person years (PY) (95%CI: 29.7–45.9). Multivariable Weibull AFT regression analyses showed that type two diabetes mellitus (T2DM) (adjusted time ratio (ATR) 0.4095%CI: 0.20–0.78), hypertension (HTN) (ATR 0.54; 95%CI: [0.35, 0.82]), low high density lipoprotein cholesterol (HDL-C) (ATR 0.51; 95%CI: 0.36–0.73), and borderline high total cholesterol (TC) (ATR 0.63; 95%CI: 0.42–0.94) were a predictor of time to DR. CONCLUSION: The overall incidence of DR among patients with diabetes mellitus was estimated to be 20.15% and is becoming a public health burden in Ethiopia. Our results indicate that T2DM, HTN, low HDL-C and borderline high TC independently predicts an increased incidence/decreased survival time of retinopathy among diabetes patients. The low HDL-C, HTN, and high TC are modifiable risk factors that should be managed along with diabetes.