Incidence and severity of retinopathy of prematurity in extremely premature infants.

OBJECTIVE

To analyze incidence and severity of retinopathy of prematurity (ROP) among extremely premature infants.

DESIGN

Retrospective, longitudinal study.

PARTICIPANTS

We studied the data concerning 207 infants whose gestational ages (GAs) were equal to 27 weeks or fewer and who were admitted to a neonatal intensive care unit between July 2006 and July 2010.

METHODS

Data were extracted from the Canadian Neonatal Network, which maintains clinical information about neonates, and were confirmed by reviewing medical charts. Infants were classified into 2 groups: the GAs of the infants in group 1 were ≤ 25 weeks; those in group 2 had GAs between 26 and 27 weeks. The incidence and severity of ROP were assessed in the total screened population and between groups.

RESULTS

The overall incidence of any ROP was 64.7%; 88% of infants in group 1 had any ROP compared to 48% infants in group 2. The overall incidence of type 1 ROP was 11.6%; in group 1 it was 24.4%, compared to 2.5% in group 2. Type 1 ROP was significantly associated with birth weight in grams (p < 0.001; OR = 8.20) and GA (p < 0.001; OR = 2.46). There was no difference in mean postmenstrual age at first ROP onset between group 1 and group 2 (33.5 vs 33.9 weeks, respectively). PMA at time of ROP diagnosis was not associated with development of type 1 ROP (p = 0.75; OR = 0.94; CI 0.62-1.41).

CONCLUSIONS

Extremely premature infants with lower GA had a higher incidence of type 1 ROP. Earlier presentation of ROP did not predict development of type 1 ROP. No infant with a GA > 26 weeks at birth or birth weight > 1000 g had type 1 ROP.