Receiver operating characteristic (ROC) curves to identify birth weight cutoffs to predict overweight in Mexican school children

Objective: To identify birth weight cutoffs to predict overweight in school children and adolescents from Chilpancingo, Mexico, in 2004. Methods: Six hundred and sixty-two male and female children between 5 and 13 years old were selected by probability sampling. Birth weight measures were extracted from vaccination cards. The school children's nutritional status was defined using specific body mass index (BMI) cutoffs according to sex and age. Predicting equations were built using linear regression models. Areas under the receiver operating characteristic (ROC) curves were calculated and two-graph (TG) ROC curves were plotted, respectively, to detect global accuracy and to identify birth weight cutoffs corresponding to the intersection of sensitivity and specificity curves. Results: Overweight prevalence was higher in female (46%) than male school children (38.5%). Among adolescents, overweight prevalence was also higher in females (43.5%) than males (38.9%). BMI average and birth weight deciles showed a linear relation. Areas under ROC curves showed values >= 78% in each stratum of sex and age, depicting a difference by sex in adolescents. TG-ROC curves showed that birth weight cutoffs were slightly higher in boys than in girls, and the sensitivity/specificity intersections were >= 0.70. Conclusions: The study results showed that birth weight cutoffs can be used as overweight markers in childhood and adolescence, being useful as a screening strategy to detect risk groups.