Discriminant analysis of volume-time and flow-volume parameters between healthy adults and asthmatic patients.

Volume-time (V-T) and flow-volume (F-V) curves were measured in all the subjects of nonsmoking young males (mean value 26.3 yrs.), healthy and asthmatic. Eleven parameters of pulmonary function tests, which were composed of two V-T, six F-V, and three mean time constants (MTC) parameters, were calculated from the curves. These were used in the discriminant analysis through all possible selection procedures (APSP) to make clear the importance of the F-V recognition. In using only one parameter, V75, which was one of the F-V parameters, showed the lowest probability of misclassification, 18.78%, and was the most useful parameter to discriminate the two groups. The probability of misclassification of the eleven parameters showed 15.46%, and that of the six F-V ones showed 17.45%. Though the probability of the six F-V ones was higher than that of the eleven ones, it was lower than that of the twoV-T or of the three MTC ones. Therefore the six F-V parameters including V75 was sufficient to discriminate the two groups of subjects. Thus it was made clear that the flow-volume recognition was important by the discriminant analysis.