The influence of gestational age on the dynamic behavior of other risk factors associated with retinopathy of prematurity (ROP)

Abstract

Background: Improved survival of preterm neonates has increased the incidence of retinopathy of prematurity (ROP) in many middle-income countries.

Aim: This study aimed to verify the main risk factors for the development of ROP according to different gestational age (GA) groups.

Methods: A prospective cohort study including infants weighing < or =1,500 g or GA < or =32 weeks at birth was conducted. The main clinical outcomes were the occurrence of any stage of ROP and severe ROP. The perinatal variables considered for the study were: birth weight; GA; gender; to be small for GA (SGA); weight gain from birth to the sixth week of life; use of oxygen in mechanical ventilation or nasal CPAP; multiple gestations; therapeutic use of surfactant, indomethacin, and erythropoietin; occurrence of sepsis, meningitis, intraventricular hemorrhage, and patent ductus arteriosus; need for and volume of blood transfusion; and 10-min Apgar score. The patients were divided into three groups according to GA: (group 1) infants of GA < or =28 weeks at birth (n = 100); (group 2) infants of GA = 29-31 weeks at birth (n = 215); and (group 3) infants of GA > or =32 weeks at birth (n = 152).

Results: A total of 467 newborn infants were included. Mean BW and GA in the total cohort were 1,216.5 g (+/-278.3) and 30.3 weeks (+/-2.2), respectively. Gestational age groups were not matched for BW and SGA. Any stage of ROP occurred in 111 patients (23.8%) and 24 (5.1%) patients developed severe ROP. Only BW and volume of blood transfusion were significant factors for the occurrence of any stage of ROP in all groups. In group 1, GA, the twin situation, and use of erythropoietin were statistically significant factors. In group 2, only GA and need for blood transfusion were significant. In group 3, use of oxygen in mechanical ventilation, sepsis, and need for blood transfusion were significant for ROP onset. The logistic regression determined that patients in groups 2 and 3 were less likely to develop ROP than patients in group 1.

Conclusions: Patients in groups 1 and 2 developed ROP due to general immaturity, whereas bigger babies, of GA > or =32 weeks, developed ROP because they were "sicker" babies with more comorbidities.