No clinical correlation between bilirubin levels and severity of retinopathy of prematurity

PURPOSE: To evaluate the hypothesis that bilirubin has a protective effect against the development of severe retinopathy of prematurity (ROP). METHODS: An assessment of 76 infants born at 24 and 25 weeks' gestation and admitted to the level III neonatal intensive care unit at Saitama Children's Medical Center was made. Indirect ophthalmoscopy fundus examinations were performed on all infants to identify the degree and progression to threshold ROP. We analyzed the daily bilirubin levels and grouped the patients according to the severity of ROP based on the infant's worst ROP examination. The first group was comprised of infants with less than stage 3 ROP and infants with stage 3 ROP. The second group was infants with less than prethreshold ROP or prethreshold ROP, and infants with threshold ROP. Next, we divided the infants into 3 groups: less than prethreshold ROP, prethreshold ROP, and threshold ROP. The daily changes in serum bilirubin concentrations during the first 14 days of life were determined for each infant. Three groups (less than prethreshold ROP, prethreshold ROP, and threshold ROP) were comparable as to their basic data, clinical characteristics, and treatments. RESULTS: ROP was found in 76 infants. There were no statistical differences in the clinical characteristics and treatments, excluding the duration of phototherapy, among the 3 groups. During the first 14 days of age, there were no significant differences in the daily mean bilirubin concentrations according to the groups separated by severity of ROP. CONCLUSION: These results indicate that there is no distinct protective effect of bilirubin on the development of severe ROP.