ROP STRATEGY

WINROP (www.winrop.com), a new web-based surveillance system, could be a valuable tool for predicting the development of severe retinopathy of prematurity (ROP) in extremely preterm infants.

WINROP is an acronym for Weight, IGF-1, Neonatal, Retinopathy Of Prematurity. It was initially developed with the goal of improving ROP screening so that it could target infants at the greatest risk for developing sight-threatening disease.

Results from initial testing and from subsequent studies involving cohorts of children in the US, Europe, Asia and South America validated its performance. However, findings from thesis research conducted by Pia Lundgren, doctoral student, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden, suggest an opportunity to improve the specificity of WINROP as well as a strategy for reducing a child's risk for developing severe ROP.

“Current guidelines for ROP screening are based only on gestational age at birth and/or birth weight. However, only five per cent to 10 per cent of infants who become subjects for screening based on those criteria go on to develop severe ROP requiring treatment. Limiting the screening to children most at risk would reduce unnecessary exposure of many fragile infants to the stress of frequent screening examinations and burden on the healthcare system,” said Ms Lundgren.

“To our knowledge, WINROP is the first and only validated web-based surveillance system for estimating an individualised risk of developing severe ROP. However, its performance may be improved through the addition of novel risk factors. Validation testing of a new prototype will be undertaken in the near future.”

In its original iteration, WINROP incorporated serum levels of IGF-1 and weekly weight measurements. Subsequent study determined that IGF-1 data could be removed from the algorithm without compromising its performance, and so WINROP currently calculates risk of developing severe ROP based only on birth weight, gestational age and weekly weight measurements.

With an interest in evaluating growth and nutrition variables as predictors of severe ROP, Ms Lundgren undertook a series of analyses looking at potential roles of infant weight and weight gain at first detection of ROP, birth weight deficit, and energy and macronutrient intake during the first weeks of life.

Risk prediction

First undertaking a validation study using data from 407 extremely preterm infants, Ms Lundgren corroborated previous research showing the algorithm had very high sensitivity, identifying 96 per cent of children who went on to require treatment for ROP. However, its specificity was only 24 per cent.

A retrospective analysis led to the determination that risk prediction could be improved by incorporating weight gain at the time the algorithm first signals an infant is at high risk of developing severe ROP.

Analyses performed using another cohort including 147 children determined that an algorithm including gestational age at birth and weight standard deviation score at first detection of ROP predicted ROP requiring treatment with high accuracy.

Looking at nutritional intake as a risk factor for severe ROP, Ms Lundgren’s research showed that macronutrient intake during the first four weeks of life was poor overall. Logistic regression analyses identified associations between low intake of energy, fat and carbohydrates and an increased risk of developing severe ROP.

Compared with their counterparts who did not develop severe ROP, infants who did were also found to have a lower mean energy intake during the first four weeks of life.

A multivariate regression analysis incorporating a variety of other risk factors unrelated to age, weight, growth or nutrition showed that energy intake independently predicted severe ROP risk. According to the results, the odds of developing severe ROP were reduced 24 per cent for each 10kcal/kg/day increase in energy intake.

“Improving nutrition intake is challenging in these babies who are likely to have feeding difficulties, although it may be possible through enteral and parenteral nutrition. Nevertheless, further research is needed to determine if it could be an effective strategy for reducing the risk of severe ROP in extremely preterm infants,” Ms Lundgren said.

Pia Lundgren: pia.lundgren@gu.se