NEW YORK (Reuters Health) – Weekly weight measurements can accurately predict which preterm infants are likely to develop proliferative retinopathy of prematurity (ROP) requiring treatment, according to study findings published in the April issue of Pediatrics.

This study, Dr. Ann Hellström told Reuters Health, shows that “a simple measure as weight gain is very closely associated to vessel development and therefore we can use weight development to identify early (months before we can see the disease needing treatment) infants at risk for the retinal vessel disease.”

“This gives us possibilities to undertake measures to optimize weight development in these fragile infants and possibly prevent sight-threatening retinopathy of prematurity,” added Dr. Hellström, who is a professor of pediatric ophthalmology at Queen Silvia Children’s Hospital, Sahlgrenska Academy at University of Gothenburg, Göteborg, Sweden.

The risk for significant ROP is predicted by low birth weight or gestational age (often < 1500 grams or < 32 weeks gestation), the investigators note in their report, and at-risk infants undergo serial ophthalmologic examinations to identify the minority of infants (roughly 10%) who would benefit from treatment. In their retrospective study, Dr. Hellström’s team found that a slowdown in postnatal growth (weight gain) is a simpler, faster, and less costly and stressful way to identify children at risk for developing proliferative ROP severe enough to warrant ophthalmologic examinations. In the study, the researchers retrospectively entered weekly weights from birth to postmenopausal week 36 into a surveillance algorithm that gave an alarm when the rate of weight gain decreased to a certain level, indicating a need for an eye exam. In development of the algorithm, the expected weight gain was estimated from data for a group of preterm infants who did not develop ROP or developed only stage 1 ROP, the team notes. Weekly weights were recorded for all 354 premature infants screened and/or treated for ROP at Sahlgrenska University Hospital from 2004 to 2007. One child was excluded due to nonphysiologic weight gain (hydrocephalus). According to the investigators, no alarm was given for 127 (36%) of 353 children. For 141 infants (40%), an alarm at “low risk” was given after postmenopausal week 32 and none of these infants developed ROP requiring treatment. Of the remaining 85 children (24%) who received an alarm at low risk before 32 postmenstrual weeks or a high-risk alarm, 41% developed proliferative ROP and 29% were treated because of sight-threatening disease. The investigators point out that the infants who developed proliferative disease had a median chronological age after birth of 3 weeks when the alarm was given and of 8.4 weeks before the first sign of proliferative disease was seen. “The fact that very early weight deviations are associated with proliferative ROP may help to provide new insights into the nature of the disease,” they write. Not only did weekly postnatal weight gain accurately identify infants at risk for proliferative ROP early, it also correctly identified a majority of infants who were not at risk, the investigators note. If further studies confirm the value of this method, “a majority (70%) of infants would not need screening, which can be stressful for the infant and is costly for society,” Dr. Hellström told Reuters Health. “As the method allows us to focus on the right patients at the right time, it can also minimize the risk of missing infants at high risk for disease development and blindness,” she added. Reference:
Pediatrics 2009;123:e638-e645.