Postconceptional age at the treatment of retinopathy of prematurity in inborn and referred preterm infants from the same institution

Purpose: The outcomes of the treatment of retinopathy of prematurity (ROP) seem to be better in inborn patients than in those patients who were referred for ROP treatment. This study aims to investigate the timing of treatment and the outcomes in inborn patients and in patients referred for treatment to the Hospital de Clinicas de Porto Alegre, Brazil. Methods: An institutional prospective cohort study was conducted from 2002 to 2010 and included in group 1 all inborn preterm neonates treated for retinopathy of prematurity and in group 2 all babies referred for treatment to the same institution. All of the included patients presented birth weight (BW) <= 1,500 g and/or gestational age (GA) <= 32 weeks. Main outcomes were postconceptional age at the treatment and one year follow-up outcomes in both groups. The considered variables were: BW, GA, stage and location of retinopathy of prematurity at treatment. Results: Group 1 comprised 24 inborn patients. Mean BW and GA at birth were 918 +/- 232 g and 28.2 +/- 2.1 weeks, respectively, and median post-conceptional postconceptional age at treatment was 37 weeks. Group 2 comprised 14 infants transferred for treatment. Mean BW and GA at birth were 885 + 188 g and 28.2 + 2.4 weeks, respectively, and median postconceptional age at treatment was 39 weeks. Mean BW and GA were similar in both groups (P=0.654 and P=0.949, respectively), but the difference among the postconceptional age was significant (P=0.029). Conclusions: Inborn patients were treated for retinopathy of prematurity during the 37(th) week of postconceptional age while transferred patients were treated, usually, after the 39(th) week postconceptional age. The worst outcomes observed among referred patients could be partially explained by the delayed time for treatment.