Importance: 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.
Objective: To determine the precise contemporary estimates of the prevalence and incidence of STDR in patients with type 2 diabetes mellitus in Taiwan.
Design, setting, and participants: 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.
Main outcomes and measures: Procedure codes were used to determine the diagnosis of STDR.
Results: 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).
Conclusions and relevance: 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.