Weight gain measured at 6 weeks after birth as a predictor for severe retinopathy of prematurity: study with 317 very low birth weight preterm babies

Recent studies suggest that postnatal weight gain can play an important role in the development of retinopathy of prematurity (ROP). To analyze the low weight gain (WG) from birth to 6 weeks of life to predict the development of severe retinopathy of prematurity (ROP) among very low birth weight preterm babies (VLBW). A prospective cohort study included 317 newborns with birth weight (BW) a parts per thousand currency sign1,500 g and gestational age (GA) a parts per thousand currency sign32 weeks. The main outcome was the development of severe ROP (defined as threshold ROP and higher stages of ROP). In all patients, the proportion of the WG was defined as the preterm weight measured at 6 weeks of life minus the BW divided by the BW. Seventeen risk factors for ROP were studied by univariate analysis. Chi-square test and Student's t-test were used to compare no-ROP/mild ROP patients and severe ROP patients. Logistic regression and receiver operating characteristic (ROC) curve were used to determine if the WG proportion was independently related to severe ROP development and if it was capable of predicting severe ROP. Ophthalmological examinations started between the fourth and sixth week of life, and were repeated until the 45th week of postmenstrual age. Weight gain proportion was always calculated at completed 6 weeks of life. Mean GA and mean BW of the whole cohort were 29.6 weeks (+/- 1.9) and 1,124 grams (+/- 239.5) respectively. After logistic regression, the low WG proportion under 51.2% from the BW, measured at 6 weeks of life, showed OR 3.007 (95%CI: 1.195-7.566; P = 0.019), for severe ROP, when adjusted for BW and for any stage intraventricular hemorrhage. Area under the ROC curve was 0.63 (95%CI: 0.495-0.761; P = 0.037). For the discriminative cutoff of 51.2% of the WG proportion, sensitivity and specificity values were 66.3% and 62.6% respectively. Positive and negative predictive values were 10.2% and 94.7% respectively. Low WG by six weeks of life is an important and independent risk factor for severe ROP and is capable to predict the development of severe ROP in most patients that needed treatment.