[Prediction formulas for pulmonary function tests expressed in linear and exponential form for healthy Japanese...

We studied 21 parameters of pulmonary function in 172 healthy Japanese adult smokers and non-smokers ranging from 18 to 83 years of age. Prediction formulas for each parameter were calculated in both linear and exponential form using multiple regression analysis with regard to sex, age, height and weight. The exponential form was superior to the linear form for V25, V50, PEF, FVC, VC, FEV1.0, FEV1.0%, TLC, DLCo and DL/VA, namely, the parameters whose predictive value decreases with aging. In particular for V25, only the exponential form of the predictive formula could be applied for subjects with advanced age. For PMI, LCI, IDI, pulmonary N2 clearance delay, and single breath delta N2, indices for unevenness of intrapulmonary gas distribution, there has been no previous report about their predictive formulas and ours is the first. These predictive formulas all showed increasing values with aging, and showed higher predictive values in females than in males, except for delta N2. These parameters require further study with respect to their normal value ranges and differences between males and females.