Discriminant analysis of pulmonary function parameters--mild asthmatics versus moderate asthmatics--.

Maximal expiratory volume-time and flow-volume (MEVT and MEFV) curves were constructed from the measurements of young male nonsmoking, mild and moderate asthmatic patients (mean age, 29.7 yrs.). Eleven parameters of the pulmonary function tests, two MEVT, six MEFV, and three mean time constant (MTC) parameters, were calculated from the curves. These parameters were used in 15 analyses through the all possible selection procedure (APAP) discriminating between mild and moderate asthmatics. The probability of misclassification was computed with each of the eleven parameters, and all eleven probabilities thus obtained were compared with each other. This procedure showed us that the probability of misclassification ranged from 30.83% to 45.40% and that the most useful parameter was MTC50-25. The probability of misclassification computed using all eleven parameters (total parameter group) was 15.90%. The discriminant analysis indicated that the flow-volume patterns varied according the severity of bronchial asthma, thus, the flow-volume curve was considered to be important in analyzing the severity of bronchial asthma.