Does height catch‐up in schoolchildren have an effect on bone mass in adolescents? Analysis in a Brazilian birth cohort

Abstract

ObjectiveTo analyze the effect of height catch‐up at school age on the bone mass of adolescents of a Brazilian birth cohort. MethodsA cohort study using data obtained from the three moments (birth, 7/9 years and 18/19 years of age) of the Cohorts‐RPS study. Height catch‐up was defined based on the difference between the schoolchild's z‐score and birth z‐score. The adolescents’ bone mineral mass was analyzed using the z‐score index for the lumbar spine measured by dual emission X‐ray absorptiometry. A theoretical model was developed for the proposed analysis using directed acyclic graphs paired through the nearest‐neighbor matching propensity score using the STATA software, version 14.0. The level of significance was set at 5%. ResultsOf the 297 studied children, 24.5% achieved height catch‐up. The bone mass below the expected for age was observed in 5.39% of the subjects. The mean lumbar spine z‐score was −0.34 (±1.01). After the adjustment, no effect was observed between height catch‐up at school age and bone mass in adolescents (Coeff=0.598; 95% CI −0.117 to 1.313; p=0.101). ConclusionEven using the directed acyclic graphs and the causal inference method by adjusting the propensity score, the height catch‐up did not seem to affect bone mass in adolescents, a result perhaps related to the sample size.