Identifying Adolescents at Risk for Depression: A Prediction Score Performance in Cohorts Based in 3 Different Continents.

OBJECTIVE: Prediction models have become frequent in the medical literature, but most published studies are conducted in a single setting. Heterogeneity between development and validation samples has been posited as a major obstacle for the generalization of models. We aimed to develop a multivariable prognostic model using sociodemographic variables easily obtainable from adolescents at age 15 to predict a depressive disorder diagnosis at age 18 and to evaluate its generalizability in 2 samples from diverse socioeconomic and cultural settings. METHOD: Data from the 1993 Pelotas Birth Cohort were used to develop the prediction model, and its generalizability was evaluated in 2 representative cohort studies: the Environmental Risk (E-Risk) Longitudinal Twin Study and the Dunedin Multidisciplinary Health and Development Study. RESULTS: At age 15, 2,192 adolescents with no evidence of current or previous depression were included (44.6% male). The apparent C-statistic of the models derived in Pelotas ranged from 0.76 to 0.79, and the model obtained from a penalized logistic regression was selected for subsequent external evaluation. Major discrepancies between the samples were identified, impacting the external prognostic performance of the model (Dunedin and E-Risk C-statistics of 0.63 and 0.59, respectively). The implementation of recommended strategies to account for this heterogeneity among samples improved the model's calibration in both samples. CONCLUSION: An adolescent depression risk score comprising easily obtainable predictors was developed with good prognostic performance in a Brazilian sample. Heterogeneity among settings was not trivial, but strategies to deal with sample diversity were identified as pivotal for providing better risk stratification across samples. Future efforts should focus on developing better methodological approaches for incorporating heterogeneity in prognostic research.

The relationship between body mass index and behavior in children.

OBJECTIVE: To examine reciprocal relationships between body mass index (BMI) and internalizing and externalizing problems from infancy through middle childhood, with a focus on sex and history of overweight. STUDY DESIGN: Data from 1254 children in the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development were used to conduct longitudinal analyses of the relationship between BMI and scores on the Child Behavior Checklist from age 2 years through the 6th grade. RESULTS: BMI and behavior problems demonstrated stability across the 7 measurement occasions. No consistent relationship between BMI and behavior problems was evident before school entry, but higher BMI was associated with later internalizing problems beginning in the 1st grade for boys and girls. Higher BMI was not associated with increased conduct problems. CONCLUSIONS: As children move into middle childhood, higher BMI is associated with increased likelihood of developing internalizing problems. Health care providers should monitor BMI as children enter school and provide guidance to parents regarding emerging symptoms of anxiety and depression.