The Relationship Between Discordant Growth in Twin Pairs and the Development of Retinopathy of Prematurity (ROP)

Abstract

Purpose : ROP is a leading cause of childhood blindness characterized by incomplete peripheral vascularization followed by neovascularization of the retina. The relationship between ROP and birth weight in singletons is well studied, but the effect of discordant growth in twins on ROP is understudied. In this retrospective cohort study using data from an ROP registry at an academic center, we investigated the relationship between discordant growth in preterm twin pairs and the development of any ROP (type 1, type 2, or low-grade ROP).

Methods : Only twins with a surviving co-twin were included in the study. Twin pairs were classified as discordant if there was a >25% difference in birth weight between twins. Logistic regression using generalized estimating equations was used to assess the effect of birthweight of the smaller discordant twin on the odds of developing any ROP with and without controlling for gestational age at delivery.

Results : From a cohort of 2,083 infants that qualified for ROP screening (2006 - 2021), 36 discordant twin pairs were identified. The mean gestational age of discordant twins was 29.6 (SD=2.2) weeks and mean birth weight was 1093.9 (SD=382.7) grams. Among discordant twins, lower gestational age at delivery (weeks) (OR=2.899, 95% CI (1.682 – 4.997), p<0.001) and lower birthweight (grams) (OR=1.006, 95% CI (1.004 – 1.009), p<0.001) were significantly associated with increased odds of any ROP. The smaller twin within a discordant twin pair had increased odds of developing any ROP (OR=2.728, 95% CI (1.270–5.858), p=0.010) compared to the larger twin. The effect of varying percent differences in discordance on ROP outcomes is shown in Figure 1. This association remained significant when adjusting for gestational age at birth (OR=6.492, 95% CI (2.123 – 19.854), p=0.001).

Conclusions : In preterm twins with discordant growth the smaller twin is significantly more likely to develop any ROP. This relationship persisted with varying percent differences in discordance. Studying twins allows for direct comparison of infants of identical gestational age, offering a method to study the effects of birth weight on ROP development. This information will assist ophthalmologists in developing screening and prevention strategies for ROP in preterm discordant twin pairs.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.