Identifying children at high risk for overweight at school entry by weight gain during the first 2 years.

OBJECTIVE To assess the best anthropometric predictor from birth to 2 years for later overweight, based on recent studies reporting that large infant weight or length gain predicts subsequent overweight. DESIGN Retrospective cohort study. SETTING Southern Germany. PARTICIPANTS German children (n = 4235) aged 5.0 to 6.9 years. MAIN OUTCOME MEASURES Overweight at school entry was defined according to sex- and age-specific body mass index cutpoints proposed by the International Obesity Task Force. Weight, length, body mass index, and ponderal index differences between birth, 6 months, 12 months, and 24 months of age were compared by receiver operating characteristic curves and predictive values. RESULTS For all variables, the largest area under the receiver operating characteristic curve was observed with a 24-month follow-up: 0.76 (95% confidence interval [CI], 0.74-0.79) for weight, 0.70 (95% CI, 0.67-0.72) for body mass index, and 0.58 (95% CI, 0.55-0.61) for length gain. The highest Youden index ([sensitivity plus specificity] minus 1) for weight gain from birth to 24 months (41%) was attained for a cutpoint of 9764 g, with a corresponding positive likelihood ratio of 2.39 (95% CI, 2.20-2.59) and positive predictive value of 19% (95% CI, 17%-21%), despite an odds ratio of 5.7 (95% CI, 4.5-7.1). CONCLUSIONS Weight gain from birth to 24 months was the best overall predictor of later overweight compared with other anthropometric markers and intervals. However, the corresponding poor positive predictive value suggests that only 1 of 5 children with a large weight gain in the first 2 years is overweight at school entry and reflects an insufficient predictability in the general population.