Prevalence of diabetic retinopathy in rural China: the Handan Eye Study.

PURPOSE: To describe the age- and gender-specific prevalence, characteristics, and severity of diabetic retinopathy (DR) in a rural population in northern China. DESIGN: A population-based cross-sectional study. PARTICIPANTS: A total of 6830 Han Chinese aged 30 years and older from 13 villages of Yongnian County, Handan City, Hebei Province, China. METHODS: All participants underwent a standardized interview, a comprehensive eye examination, and fasting blood glucose testing according to the American Diabetes Association diagnostic criteria (fasting plasma glucose >or=7.0 mmol/l). Retinal photographs obtained after pupil dilation were graded for the presence and severity of DR according to the modified Early Treatment Diabetic Retinopathy Study classification system. MAIN OUTCOME MEASURES: Any DR, retinopathy grades, macular edema, or vision-threatening retinopathy. RESULTS: Of the 6830 eligible individuals participating in the study, 5597 (81.9%) had fasting blood glucose results available. Of these, 387 participants (6.9%) were diagnosed with diabetes mellitus, including 247 subjects with new diabetes mellitus (NDM) and 140 subjects with known diabetes mellitus (KDM). For these, gradable photographs were available for 368 subjects (95.1%). The overall prevalence of DR was 43.1% (95% confidence interval, 38.1-48.4) and was higher in persons with KDM (65.2%) than NDM (33.5%). The prevalence of proliferative DR, macular edema, and vision-threatening retinopathy was 1.6%, 5.2%, and 6.3%, respectively, with 12.1% with KDM having untreated vision-threatening DR. No age- or gender-related differences were present. The prevalence of DR was strongly related to duration of disease. CONCLUSIONS: Our study reports a high prevalence of DR among adults 30 years and older with diabetes in rural China. On the basis of estimates obtained from our study, we projected that in rural China, 21.1 million persons aged 30+ years have diabetes and 9.2 million have DR, including 1.3 million with vision-threatening DR. There is a pressing need for appropriate screening and management of diabetes and its complications in rural China.