This retrospective study in the August Archives of Ophthalmology assessed the effectiveness of the WINROP (weight, insulin-like growth factor, neonatal ROP) algorithm, which uses postnatal weight measurements to predict retinopathy of prematurity (ROP). The authors found that WINROP is a useful adjunct for ROP screening that identifies high-risk infants early and could potentially reduce the number of diagnostic ROP examinations.
WINROP analysis was performed retrospectively on 1,706 conventionally at-risk infants from 10 neonatal intensive care units in the United States and Canada. Use of WINROP requires (1) gestational age less than 32 weeks at birth, (2) weekly weight measurements, (3) physiologic weight gain, and (4) absence of other pathologic retinal vascular disease.
Weight measurements were entered into WINROP, which signals an alarm for an abnormal weight gain rate. Infants were classified into categories of no alarm (unlikely to develop type 1 ROP) and alarm (at risk for developing type 1 ROP).
The infants had a median gestational age of 28 weeks (range, 22 to 31 weeks) and median birth weight of 1016 g (range, 378 to 2240 g). An alarm occurred in 1,101 infants (64.5 percent), with a median time from birth to alarm of three weeks (range, 0 to 12 weeks) and from alarm to treatment of eight weeks (range, 1 day to 22 weeks). The sensitivity of WINROP was 98.6 percent and the negative predictive value was 99.7 percent.
Two infants with type 1 ROP requiring treatment after 40 weeks' postmenstrual age did not receive an alarm. Approximately 50 percent of infants who developed type 1 ROP received a WINROP alarm two weeks or less after birth and 75 percent received an alarm three weeks or less after birth.
The authors say this study validated the use of postnatal weight gain analysis by WINROP to aid early prediction of infants at high risk for type 1 ROP. They found that poor weight gain during the first weeks of life is a marker for severe ROP risk.
They say that since infants with no alarm were very unlikely to develop significant ROP, ophthalmologic examinations might be safely reduced in frequency and number for these infants, keeping in mind that WINROP is an adjunct to and not a replacement for standard ophthalmologic screening.