Risk factors for diabetic retinopathy: Findings from The Andhra Pradesh Eye Disease Study

To assess prevalence, potential risk factors and population attributable risk percentage (PAR%) for diabetic retinopathy (DR) in the Indian state of Andhra Pradesh. A population-based study, using a stratified, random, cluster, systematic sampling strategy, was conducted in the state of Andhra Pradesh in India during 1996 and 2000. Participants from 94 clusters in one urban and three rural areas representative of the population of Andhra Pradesh, underwent a detailed interview and a comprehensive dilated ocular evaluation by trained professionals. DR was defined according to the international classification and grading system. For subjects more than or equal to 30 years of age, we explored associations of DR with potential risk factors using bivariable and multivariable analyses. Population attributable risk percent was calculated using Levin's formula. Diabetic retinopathy was present in 39 of 5586 subjects, an age-gender-area-adjusted prevalence of 0.72% (95% confidence interval (CI): 0.49%-0.93%) among subjects aged >/= 30 years old, and 0.27% (95% CI: 0.17%-0.37%) for all ages. Most of the DR was either mild (51.3%) or moderate (35.9%) non-proliferative type; one subject (2.6%) had proliferative retinopathy. Multivariable analysis showed that increasing age, adjusted odds ratio (OR); 4.04 (95% CI: 1.88-8.68), middle and upper socioeconomic status group (OR); 2.34 (95% CI: 1.16-4.73), hypertension (OR); 3.48 (95% CI: 1.50-8.11) and duration of diabetes >/= 15 years (OR); 8.62 (95% CI: 2.63-28.29) were significantly associated with increasing risk of DR. The PAR % for hypertension was 50%; it was 10% for cigarette smokers. Extrapolating the prevalence of diabetic retinopathy in our sample to the Indian population suggests that there may be an estimated 2.77 million people with DR, approximately 0.07 million people with severe DR. As the population demographics change towards aging, this number is likely to increase further. Health care programs in India need to examine strategies to prevent diabetes and DR, as well as create the infrastructure required to manage this condition.