Maturation-related deviations and misclassification of stature and weight in adolescence

The present research quantifies normal deviations in stature and weight associated with variation in maturational status and describes the associated misclassification that occurs when using reference data based on chronological age. Misclassification is the likelihood that incorrect judgments will be made in assessments relative to the reference data. Based on data for 999 children of the Brush Foundation study, the absolute deviations associated with variation in maturational status, an index of misclassification P̂_mc.5 was developed to estimate the approximate probability of misclassification within an age group relative to that occurring at 5 years of age. The estimated maturation-associated deviations and P̂_mc.5 include changes in age-specific standard deviations in skeletal age (mean of hand, foot, elbow, knee, hip, shoulder) and regression coefficients (slopes) of stature-for-skeletal age and weight-for-skeletal age. Maturation-associated deviations for stature reach 11 cm for boys and 9 cm for girls, and those for weight reach 12 kg and 10.5 kg for boys and girls, respectively. P̂_mc.5 for stature at peak velocity reaches 1.3 and 2.3 in girls and boys, respectively. These levels indicate that at these ages girls will be ∼1.3 times, and boys 2.3 times, as likely to have their statures misclassified because of maturational status than at 5 years of age. For weight, P̂_mc.5 reaches 2.0 by ∼9 years of age in both sexes and reaches 3.1 for girls and 4.9 in boys during adolescence. The adolescent increase in maturation-related misclassification results primarily from changes in the size-for-maturation relationships rather than changes in the variation in maturational status per se.