Incidence and Risk Factors of the Retinopathy of Prematurity

Park, June Dong; Kweon, Jung Hae; Kim, Woong Heum; Kim, Beyong Il; Choi, Jung Hwan; Yun, Chong Ku; Khwarg, Sang In; Yu, Young Suk

Abstract

PURPOSE
Retinopathy of prematurity(ROP) continues to be a serious problem in infants who survived with neonatal intensive care. Nevertheless, there is neither available data about the incidence of ROP which may be the basis of the epidemiology, nor analysis of the risk factors of ROP in Korea. The purpose of this retrospective study was to evaluate the incidence of ROP and to analyze perinatal risk factors of ROP.
METHODS
The study population was inborn neonates of Seoul National University Hospital during the three-year period, from Jan. 1991 to Dec. 1993. The total number of infants was 5,764, and the incidence of ROP was evaluated according to gestational age and birthweight. Infants with birthweight under 1,500gram or with gestational age less than 33 weeks were involved in this study, in 168 of the 242 infants, their eyes were examined. Of these, 71 developed some degree of ROP, and 12 received cryotherapy. The comparisons of perinatal risk factors of ROP between the group with and without ROP, and in the group with ROP, between with and without cryotherapy have been made.
RESULTS
1) The cumulative incidence of ROP according to gestational age was 100% in less than 28 weeks, 96.0%, 80.4%, 66.7%, 57.3%, 44.1%, 32.2%, 23.1%, 15.8%, and 10.6% in less than 29, 30, 31, 32, 33, 34, 35, 36, and 37 weeks, respectively. 2) The cumulative incidence of ROP according to birthweight was 100% in under 750gram, 90.9%, 69.8%, 56.8%, 39.1%, 26.8%, 16.0%, and 9.9% in under 1,000gram, 1,250gram, 1,500gram, 1,750gram, 2,000gram, 2,250gram, and 2,500gram, respectively. 3) The perinatal risk factors which were statistically significant were gestational age, birthweight, Apgar score at 1 and 5 minutes, duration of hospitalization, ventilation and oxygen supply, number of transfusions, acidosis, hyperoxia, maximum fraction of inspired oxygen, maximum peak inspiratory pressure, maximum frequency, and the presence of pneumonia, apnea-bradycardia syndrome, intraventricular hemorrhage, sepsis, hypocalcemia, hyperglycemia, bronchopulmonary dysplasia, administration of aminophylline or furosemide. With linear logistic regression analysis, only gestational age (OR=0.930, 95% CI=0.887-0.975) and hyperoxia (OR=1.006, 95% CI=1.003-1.009) were proved to relate to the occurrence of ROP independently.
CONCLUSIONS
ROP was developed in 44.1% of infants less than 33 weeks and in 56.8% of infants under 1,500gram and the occurrence of ROP was related significantly only to gestational age and hyperoxia.