Overweight in Adolescence Can Be Predicted at Age 6 Years: A CART Analysis in German Cohorts

OBJECTIVE: To examine, whether overweight in adolescents can be predicted from the body mass index (BMI) category, at the age of 6, the mother's education level and mother's obesity and to quantify the proportion of overweight at the age of 14 that can be explained by these predictors. METHOD: Pooled data from three German cohorts providing anthropometric and other relevant data to a total of 1 287 children. We used a classification and regression tree (CART) approach to identify the contribution of BMI category at the age of 6 (obese: BMI>97(th) percentile (P97); overweight: P90<BMI≤P97; high normal weight: P75<BMI≤P90; third quartile: P50<BMI≤P75; below the median: ≤P50), maternal education level and maternal obesity for prediction of overweight/obesity (BMI>P90) at the age of 14. RESULTS: While 4.8% [95%CI: 3.2;7.0] of 651 boys and 4.1% [95%CI: 2.6;6.2] of 636 girls with a BMI<P75 at age 6 were overweight/obese in adolescence, prevalence increased to 41.3% [95%CI: 31.9;51.1] and 42.5% [95%CI: 33.8;51.6], respectively, in those with BMI≥P75. The lowest prevalence was 1.9% [95%CI: 0.8;3.8] in boys with a BMI≤P50 and the highest prevalence 91.7% [95%CI: 61.5;99.8] with a BMI>P97 (similar results for girls). BMI≥P75 at the age of 6 explained 63.5% [95%CI: 51.1;74.5]) and 72.0% [95%CI: 60.4;81.8] of overweight/obesity at the age of 14 in boys and girls, respectively. CONCLUSIONS: Overweight/obesity in adolescence can be predicted by BMI category at the age of 6 allowing for parent counselling or risk guided interventions in children with BMI≥P75, who accounted for >2/3 of overweight/obesity in adolescents.