Incidence of diabetic retinopathy in the Barbados Eye Studies

Purpose: To examine the 4-year incidence and risk factors for diabetic retinopathy (DR) among black participants with diabetes in the Barbados Eye Studies (BES). Design: Population-based incidence study. Setting and Participants: Four hundred ten persons with diabetes mellitus (DM) from the BES cohort, which was based on a simple random sample of Barbadians, 40 to 84 years of age at baseline. Main Outcome Measures: Development of DR, assessed by independent gradings of 30degrees color stereo fundus photographs of the disc and macula. Associations were evaluated by logistic regression analyses. Results: After 4 years, DR developed in 92 of 306 (30.1%; 95% confidence interval, 25.0%, 35.5%) persons unaffected at baseline. The incidence of DR was 31.9% in those with known DM at baseline and 20.9% in newly diagnosed DM. Clinically significant macular edema developed in 16 (4.5%) of 353 individuals at risk. Seven (6.9%) of the 101 persons with minimum or moderate DR at baseline progressed to proliferative DR. Age-specific incidence declined from 36.2% at age 40 to 49 years to 28.8% and 24.2% over the subsequent two decades, increasing to 38.2% among those greater than or equal to70 years. Risk factors for DR were increased systolic blood pressure (relative risk [RR], 1.16 [1.03, 1.31]/10 mmHg increase); use of oral hypoglycemics (RR, 2.4 [1.3, 4.2]); and use of insulin (RR, 6.1 [1.7, 22.1]) (vs. no treatment or diet only); and elevated glycated hemoglobin (GHb; RR, 6.4 [2.5, 16.0]); GHb >11.5% vs. GHb less than or equal to8%). Conclusions: High rates of incident DR were evident in the black BES population, also known to have high rates of DM. Prevention of visual loss caused by DR in this population has high priority, including optimal glycemic and blood pressure control.