Changes in Course of Retinopathy of Prematurity from 1986 to 2013: Comparison of Three Studies in the United States

Abstract

Purpose: To compare infant and retinopathy of prematurity (ROP) characteristics from 3 clinical studies conducted over a 27-year period in the United States.

Design: Secondary analysis of results of 3 clinical studies.

Participants: Infants with birth weight (BW) <1251 g.

Methods: Analysis of data from the Cryotherapy for Retinopathy of Prematurity (CRYO-ROP) and Early Treatment for Retinopathy of Prematurity (ETROP) trials and the primary data from the Telemedicine Approaches for the Evaluation of Acute-Phase Retinopathy of Prematurity (e-ROP) study.

Main outcome measures: Infant characteristics and onset, severity, and time course of ROP.

Results: Across the 3 studies, mean (standard deviation) BW and mean gestational age (GA) decreased over time from CRYO-ROP (954 g [185 g], 27.9 weeks [2.2 weeks]) to ETROP (907 g [205 g], 27.4 weeks [2.2 weeks]) to e-ROP (864 g [212 g], 27.0 weeks [2.2 weeks]), with an increase in the percentage of infants enrolled weighing <750 g (15.8% CRYO, 24.9% ETROP, 33.4% e-ROP; P<0.0001). The percentage of infants who developed ROP varied only minimally (65.8% CRYO, 68.0% ETROP, 63.7% e-ROP; P = 0.003). Moderately severe ROP (defined as prethreshold or referral warranted) varied (17.8% CRYO, 12.3% ETROP, 19.4% e-ROP; P<0.0001), whereas the time of onset of any ROP did not vary (34.3 weeks CRYO, 34.1 weeks ETROP, 34.8 weeks e-ROP).

Conclusions: The BW and GA of infants enrolled in ROP studies in the United States have decreased over the past 27 years, whereas ROP prevalence and onset of disease are stable.

Figure 1

The rate of prethreshold ROP by combination of BW and GA in ETROP and e-ROP. Since 1986, average birth weight and gestational age of <1251g birth weight premature infants at risk for ROP have decreased while ROP prevalence and onset have changed little.