Sex- and Age-Specific Prevalence and Incidence Rates of Sight-Threatening Diabetic Retinopathy in Taiwan

Abstract

The prevalence of diabetic retinopathy (DR) is high in individuals with diabetes mellitus. Published estimates for sight-threatening DR (STDR) prevalence range widely. There is a need for precise contemporary estimates of the prevalence and incidence of STDR for providing optimal strategies of clinical management in Taiwan. To determine the precise contemporary estimates of the prevalence and incidence of STDR in patients with type 2 diabetes mellitus in Taiwan. Data were collected from a representative database, the Longitudinal Health Insurance Database 2005, from 2005 to 2011, on a total of 2926 incident cases of patients with STDR among 63,582 patients with type 2 diabetes. Sight-threatening DR was defined as clinically significant macular edema, severe nonproliferative DR, or proliferative DR according to the classification of the Early Treatment Diabetic Retinopathy Study research group. Sex-specific and age-adjusted incidence and prevalence rates of STDR were analyzed for patients with type 2 diabetes and STDR identified using International Classification of Diseases, Ninth Revision, Clinical Modification codes and procedure codes. Procedure codes were used to determine the diagnosis of STDR. The number of incident cases of STDR increased in line with the increasing diabetic population during 2005-2011. Sex differences in the age-adjusted incidence rates were observed, showing a declining trend from 10.84 (95% CI, 10.69%-10.99%) to 6.00 (95% CI, 5.86%-6.14%) per 1000 person-years for women (P < .001) contrasting with an increasing trend in men, from 14.86 (95% CI, 14.71%-15.01%) to 21.89 (95% CI, 21.76%-22.02%) per 1000 person-years (P < .001). The age-adjusted prevalence rates of STDR were in decreasing trends for both sexes, with a mean of 2.75% for women and 2.87% for men. Apart from apparent sex differences in prevalence rates of STDR, increasing trends were observed among younger patients (aged <60 years). We found considerable variation in the incidence trends between sexes. Our findings provide evidence that the incident cases of STDR have increased among patients with type 2 diabetes, but the overall prevalence of STDR is in a declining trend in Taiwan, suggesting that decreased mortality rate, better diabetes management, and early detection of treatable DR might contribute to the prevalence patterns.