A Population Based Assessment of Diabetic Retinopathy in Pakistan. The National Blindness and Visual Impairment Survey

Abstract

Purpose:: To estimate the prevalence and risk factors for diabetic retinopathy (DR) in Pakistan.

Methods:: Multi-stage, cluster random sampling, with probability proportional-to-size procedures selected a nationally representative sample of adults aged ≥30 years. Diabetics were identified by a positive medical history or, in any suspected participants, a random blood glucose level of >140mg/dl. All participants underwent fundus examination, those with a visual acuity of <6/12 in either eye had an in-depth examination including fundus photography. Logistic regression modeling investigated risk factors.

Results:: 16,507 (95.3% response rate) adults included in the survey, 660 of whom were diabetic (4%). Provincial differences in prevalence of diabetes found (Punjab 5.0%; Sindh 3.3%; North West Frontier Province 3.1%, and Balochistan 0.4%, p<0.001). The prevalence was highest in the sixth decade of life (7.1%). Urban dwellers had a higher prevalence than rural dwellers (7% vs. 2.5%, p<0.001). Diabetics were more likely to have visual loss than non-diabetics (8.8% and 48% of diabetic participants were <6/60 and <6/12 respectively in their better eye compared with 4.7% and 25.9% among non-diabetics). 101 diabetic adults (15.3%) had signs of DR. The standardized prevalence of DR was 0.6% (95%CI: 0.5, 0.7%). In urban dwellers the prevalence was 1.1% compared to 0.4% in rural areas (p<0.001). 12.9% of participants with DR were <6/60 and 69.3% were <6/12. Only 0.2% of blind (<3/60) and 0.4% of visually impaired (<6/12) adults were attributed to DR. Non proliferative DR (mild or moderate) was the commonest type (70.3%), however 30 individuals had signs of active proliferative disease. Literacy, urban dwelling, increasing age and increasing body mass index were statistically significant risk factors for DR in the multivariable model.

Conclusions:: In this survey, nearly half the diabetic population was visually impaired and 1 in 6 had signs of diabetic retinopathy. We estimate 90,000 adults in Pakistan are at immediate risk of visual loss from proliferative DR. Pakistan is projected to have one of the largest increases in diabetes prevalence in the forth coming years, and effective models for screening and treatment need to be established to prevent diabetic retinopathy from becoming an important cause of visual loss.

Keywords: diabetic retinopathy • clinical (human) or epidemiologic studies: prevalence/incidence • clinical (human) or epidemiologic studies: risk factor assessment