Nationwide trends and incidence of blindness in patients with diabetic retinopathy identified using an age-period-cohort analysis

Abstract

Objectives: To estimate the epidemiologic trends of blindness in patients with diabetic retinopathy (DR) and investigate the age-, period-, and cohort-specific effects on blindness. Methods: A total of 2.5 million patients with DR aged 20 years or older were included from the Korean National Health Claims database from 2005 to 2019. Non-proliferative DR/ proliferative DR (NPDR/PDR) cohorts were constructed separately. Participants were identified as having a blindness in at least one eye. The incidence of blindness were calculated using a log-linear Poisson age-period-cohort (APC) analysis model, each effect on blindness were estimated for each study group. Results: The incidence of blindness was 1326.62 per 100,000 in the NPDR group and 3397.57 in the PDR group. The blindness rate sharply decreased after 2011, with annual decreases of 5.6% and 4.4% in the NPDR and the PDR groups, respectively. People born between 1920 and 1930 had the highest overall risk of blindness, with the risk decreasing rapidly after that. For those born after 1980, the risk started to increase in both sexes. Among the APC models, the combination model of age, period, and cohort effects showed the highest explanatory power (0.96). Conclusions: In this nationwide long-term study, blindness in DR was not due to a single epidemiologic cause but rather a combination of biological age, social determinants, and healthcare policies. The increased risk of blindness in individuals in their 20 s and 30 s may even increase in the future and should not be ignored. Therefore, vigilance of younger patients is recommended.