Ethnic Differences in the Prevalence and Risk Factors of Diabetic Retinopathy

Purpose To evaluate the prevalence and risk factors for diabetic retinopathy (DR) in the Singapore Epidemiology of Eye Diseases (SEED) Study. Design Population-based, cross-sectional study. Participants Persons of Malay, Indian, and Chinese ethnicity aged 40+ years, living in Singapore. Methods Diabetes was defined as nonfasting plasma glucose ≥200 mg/dl (11.1 mmol/l), glycated hemoglobin A1c (HbA1c) >6.5%, self-reported physician-diagnosed diabetes, or the use of glucose-lowering medication. Retinal photographs, were graded for the presence and severity of DR using the modified Airlie House classification system. Main Outcome Measures Diabetic retinopathy, diabetic macular edema (DME), vision-threatening diabetic retinopathy (VTDR), defined as the presence of severe nonproliferative or proliferative DR, or clinically significant macular edema (CSME). Results Of the 10 033 subjects, 2877 (28.7%) had diabetes and gradable photographs for analysis. The overall age-standardized prevalence (95% confidence interval [CI]) was 28.2% (25.9–30.6) for any DR, 7.6% (6.5–9.0) for DME, and 7.7% (6.6–9.0) for VTDR. Indians had a higher prevalence of any DR (30.7% vs. 26.2% in Chinese and 25.5% in Malays, P = 0.012); a similar trend was noted for any DME ( P = 0.001) and CSME ( P = 0.032). Independent risk factors for any DR were Indian ethnicity (odds ratio [OR], 1.41; 95% CI, 1.09–1.83, vs. Chinese), diabetes duration (OR, 1.10; 95% CI, 1.08–1.11, per year), HbA1c (OR, 1.25; 95% CI, 1.18–1.32, per %), serum glucose (OR, 1.03; 95% CI, 1.00–1.06, per mmol/l), and systolic blood pressure (OR, 1.14; 95% CI, 1.09–1.19, per 10 mmHg). Diastolic blood pressure (OR, 0.74; 95% CI, 0.65–0.84, per 10 mmHg increase), total cholesterol (OR, 0.87; 95% CI, 0.80–0.95, per mmol/l increase), and low-density lipoprotein (LDL) cholesterol (OR, 0.83; 95% CI, 0.74–0.92, per mmol/l increase) were associated with lower odds of any DR. Risk factors were largely similar across the 3 ethnic groups. Conclusions Indian Singaporeans have a higher prevalence of DR and DME compared with Chinese and Malays. Major risk factors for DR in this study were similar across the 3 ethnic groups. Addressing these risk factors may reduce the impact of DR in Asia, regardless of ethnicity.