Effect of Adjusting for Tanner Stage Age on Prevalence of Short and Tall Stature of Youths in the United States.

ABSTRACT

OBJECTIVE: To evaluate the extent to which pubertal timing alters the classification of extremes of attained stature across race-ethnicity groups of youths in the US. STUDY DESIGN: We performed analyses of height and Tanner staging data of 3206 cross-sectional national sample of youths ages 8-18 years (53% male, n = 1606), 72% of whom were non-Hispanic white, 9% Mexican American, and 19% non-Hispanic black . Specialized growth models were used to derive Tanner-stage-age-adjusted z scores (TSAHAZ). The prevalence of shortness (<-1SD) and tallness (≥+1SD) status was quantified using TSAHAZ. RESULTS: Highly variable patterns of prevalence of shortness and tallness via chronologic age height z score (CAHAZ) were observed in results stratified by race-ethnicity and sex. Tallness CAHAZ prevalence was high among non-Hispanic white and non-Hispanic black male youths relative to Mexican American (40.0%-43.3% vs 20.5%) with a similar pattern in female youths. In both sexes, this pattern was eliminated with TSAHAZ, with Mexican American youth becoming statistically not different from their non-Hispanic white and non-Hispanic black peers. CONCLUSIONS: Differences in timing of puberty between race-ethnicity groups affects estimated prevalence of shortness and tallness of attained height that remains uncaptured with CAHAZ. Adjustment for pubertal development might help isolate crucial determinants of attained stature and other aspects of body composition that may be most responsive to intervention programs in populations. The curves developed by adjusting for pubertal status may help the clinician avoid misclassification of children with early and late pubertal development.