Correlation between risk factors during the neonatal period and appearance of retinopathy of prematurity in preterm infants in neonatal intensive care units in Alexandria, Egypt

Background: This study aimed to identify the main risk factors for development of retinopathy of prematurity (ROP) in neonatal intensive care units in Alexandria, Egypt, from January 2010 to January 2012. Methods: A prospective cohort study was undertaken in infants weighing, 1250g and maternal postmenstrual age, 32 weeks if there was concern about prolonged exposure to oxygen. The main clinical outcomes were occurrence of any stage of ROP and in particular severe ROP. Perinatal variables considered were: birth weight, gestational age, gender, method of ventilation (nasal continuous airway pressure or intermittent mechanical ventilation), packed red blood cell and/or plasma transfusion, occurrence of sepsis, neonatal indirect hyperbilirubinemia, intraventricular hemorrhage, and patent ductus arteriosus. After obtaining informed consent from the parents, infants at risk were examined for ROP using indirect ophthalmoscopy, ie, RetCam II fundus photography. Results: The study included 152infants of mean gestational age 31.02 weeks and mean birth weight 1.229kg. Seventy-two cases (47.5%) were male and 80 cases (52.5%) were female. Of the cases screened, 100 (65.6%) had no ROP, 52 had ROP of any stage (34.4%), and 27 (18%) had stage 1, five (3.3%) had stage 2, 17 (11.5%) had stage 3, and three (1.6%) had stage 4 disease. No infants had stage 5 ROP. Of all our cases with ROP, 15 (28.6%) had prethreshold disease type 1 that required treatment, comprising 9.8% of all cases screened for ROP. Using stepwise logistic regression analysis, all risk factors studied were found to be significantly associated with the development of ROP, except for neonatal indirect hyperbilirubinemia. Severity of ROP was inversely proportional to birth weight and gestational age. Conclusion: ROP occurred in 34.4% of all infants screened in the neonatal intensive care units at three obstetric hospitals in Alexandria. The main risk factors for development of threshold ROP by regression analysis were low birth weight, gestational age, method of ventilation, need for packed red blood cell and/or plasma transfusion, occurrence of sepsis, intraventricular hemorrhage, and patent ductus arteriosus but not neonatal indirect hyperbilirubinemia. We suggest that both immaturity and compromised pulmonary function are both important etiological factors in the development of ROP.