Interindividual variation in pubertal growth patterns of ventilatory function, standing height, and weight.

We studied interindividual variation in pubertal growth patterns from peak growth velocities (PGV) and peak growth ages (PGA) of ventilatory function, standing height, and weight in a selection of 144 boys from a longitudinal survey of 404 pupils in a Dutch secondary school. Measurements were made at intervals of approximately 0.5 yr between 1978 and 1985. Between 9 and 14 measurements were available for each selected individual. Average age on enrollment was 12.7 years. Ventilatory function was characterized by FVC, FEV1, peak expiratory flow (PEF), and maximal expiratory flow at 50% of the FVC (MEF50), derived from maximum expiratory flow volume (MEFV) curves. PGVs and PGAs were derived from monotonically increased regression splines, fitted to the data of each individual and each variable separately. The 90% percentile ranges of PGA were approximately 4.5 yr in all variables. In almost all boys, the PGA of height occurred earlier than that of ventilatory function, but the magnitude of the time lag varied considerably. Median PGAs agreed well with peak growth ages derived from average growth velocity curves fitted on exactly the same data. However, median PGVs were 1.25 to 1.40 times higher than the corresponding estimates from the average curves. The latter finding implies that in almost all cases, individual development deviates considerably from development suggested by average growth profiles. No differences in PGA and PGV were found between subjects with a prepubertal history of respiratory symptoms and those without. The large interindividual variations in PGA and PGV, and in the time lag between growth of height and of ventilatory function, are not accounted for in cross-sectional reference equations. These equations are therefore not suitable to predict individual development during adolescence.