[Longitudinal analysis of the development of pulmonary function in childhood]

In order to evaluate, longitudinally, the development of pulmonary function in childhood, maximal expiratory flow volume (MEFV) curves, height, and weight of 441 fourth grade school children were measured in 1980, and again two and four years later. The same instruments were used to measure pulmonary function, height, and weight in all three surveys. In addition, pulmonary function tests were performed by the same examiner in all three surveys. Three hundred and twenty five children had acceptable results for MEFV curves at all of three surveys. Two simple linear models were fitted to the distribution of pulmonary function measurements. One has age, height, functional level of the individual child, and the interaction of age and height as explanatory variables. In the other model, the natural logarithm of pulmonary function measurements was considered as a dependent variable, and age, height, and functional level of the individual child were employed as explanatory variables. The models explained the distribution of forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and maximal expiratory flows (MEFs) quite well both in males and in females. These results suggest that the development of FVC and FEV1 against height was not linear, and that age was an independent contributor to the development even after adjusting for height. Tracking in the development of MEFs as well as FVC and FEV1 was observed, suggesting that functional development of MEFs for an individual child could be evaluated accurately utilizing percentile curves as in the case of FVC and FEV1.