Oxygen administration to the premature infant. A two-edged sword

Incidence and risk factors for retinopathy of prematurity in very low and in extremely low birth weight infants in a unit-based approach in southern Brazil

AIMS

To analyse the incidence and risk factors for retinopathy of prematurity (ROP) and survival rates among extremely low birth weight (ELBW) and very low birth weight (VLBW) preterm infants.

METHODS

A prospective cohort study of 352 infants admitted at a teaching hospital, Hospital de Clinicas de Porto Alegre, Brazil, between October 2002 and December 2006, was screened for ROP. The ELBW group comprised infants whose birth weight (BW) was < or = 1000 g and the VLBW group comprised those infants whose BW were > 1000 g and < or = 1500 g. Perinatal risk factors for ROP were assessed using univariate and multivariate analysis.

RESULTS

Of the 352 neonates screened, 88 were ELBW babies. Survival rates among ELBW and VLBW were 47.8 and 88.7%, respectively. ROP affected 48.9% of ELBW infants and 18.2% of VLBW babies. Threshold disease occurred in 21 patients, 15 of whom were born weighing < 1000 g. Only 2.3% of the neonates born with more than 1000 g developed treatable disease. Univariate analysis showed that gestational age (GA), BW, use of indomethacin and erythropoietin, blood transfusions, and intraventricular haemorrhage were associated with ROP. After logistic regression, the most important adjusted risk factors were BW (OR: 1.002;95% CI: 1.001-1.003; P=0.003), GA (OR: 1.254;95% CI: 1.082-1.455; P=0.003), and use of erythropoietin (OR: 2.486;95% CI: 1.182-5.231; P=0.016).

CONCLUSION

This study showed reduced survival rates, high incidence of ROP, and a greater need of treatment among ELBW infants as compared to VLBW babies admitted in this institution.