The incidence and risk factors of retinopathy of prematurity in South Korea: A nationwide cohort study.

Retinopathy of prematurity (ROP) is a major treatable cause of childhood blindness. Thus, epidemiological investigations are necessary for detecting and preventing ROP. Determining risk factors for ROP are also essential to improve screening methods. Therefore, we aimed to investigate the incidence and risk factors of ROP in Korea. The National Health Insurance Service (NHIS) covers almost all Koreans. Furthermore, the National Health Screening Program for Infants and Children (NHSPIC) is a government-run, health-screening program for children aged < 6 years. We used the NHIS-Infants and Children's Health Screening cohort database to evaluate the incidence of preterm infants and ROP. The database contains data on 84,005 participants, drawn from 5% of the NHSPIC survey on participants born annually during 2008 to 2012. Sociodemographic factors and systemic diseases were assessed as potential risk factors for ROP. We identified 2615 premature infants (3.11%); 846 of them had ROP (cumulative incidence: 32.4%). Although preterm births increased annually in 2008 to 2012, the ROP incidence in preterm infants did not increase by the birth year. Twenty patients (2.4%) with ROP underwent laser photocoagulation or surgery. Extremely low birth weight was a high risk factor (odds ratio [OR] = 49.86, P < .001). Moreover, chorioamnionitis (OR = 2.77, P = .028), respiratory distress syndrome (OR = 4.09, P < .001), apnea (OR = 1.59, P = .008), anemia (OR = 2.41, P < .001), and intraventricular hemorrhage (OR = 2.34, P < .001) were found to be risk factors for ROP. In conclusion, the incidence of premature babies increased between 2008 and 2012. However, the overall incidence of ROP among premature infants remained unchanged by birth year. Our findings revealed the roles of birth weight, respiratory conditions, anemia, and intraventricular hemorrhage in ROP.