Time to regain birth weight - a marker to predict the severity of retinopathy of prematurity?

Background: Poor weight gain in the first few weeks of life has been studied as a predictor of retinopathy of prematurity (ROP). Our aim was to assess whether time taken to regain birthweight (BW) be used as an additional marker to identify infants with type 1 ROP. Methods: In this retrospective study, preterm infants (< 27 weeks gestational age at birth) born during the period from 1/1/2010–31/12/2015 at a tertiary neonatal intensive care unit in Australia were included. Twenty-seven preterm infants with Type 1 ROP were identified. Controls (No ROP or ROP other than type 1) were matched with cases on gestational age at birth and BW (1:4 ratio). Data were collected from the database and medical records. Results: The median (IQR) gestational age for Type 1 ROP and control groups were 24 (24–26) and 25 (24–26) weeks respectively and median (IQR) BW for Type 1 ROP and control groups were 675 (635–810) and 773 (666–884) grams respectively. Preterm infants with Type 1 ROP were more likely to be small for gestational age (SGA) (18.5% vs 3.7%, p = 0.015) and had increased weeks on oxygen therapy (median 11.9 vs 9.1, p = 0.028). Time to regain BW was longer in preterm infants with type 1 ROP than controls but did not reach statistical significance (median 9 vs 7 days, OR 1.08, 95% CI 1.00–1.17, p = 0.059) adjusted for SGA and duration of oxygen therapy. The area under the curve from the time to regain BW model with adjustment for SGA and duration of oxygen therapy was 0.73 (95% CI 0.62–0.83). Conclusion: We hypothesize that time to regain BW has potential to aid prediction of Type 1 ROP and this warrants further investigation in a larger prospective study.