Reference values for respiratory function tests in males: prediction formulas with tobacco smoking parameters

Abstract

Prediction equations for respiratory function tests were obtained by multiple regression of data from 263 healthy men. The material was evenly distributed in the ages 20-70 yr, .apprx. 1/3 each of non-smokers, smokers and ex-smokers. Measurements were done of lung volumes (with body plethysmograph), airways resistance, ventilatory capacity including flow-volume registration, gas distribution and closing volume, transfer factor and static elastic recoil pressures of the lung with calculation of static compliance. The parameters'' age, height, weight, years of tobacco smoking and grams of tobacco smoked each day showed significant correlation with the outcome of the test in most of the respiratory function tests. A set of basic regression equations including these parameters was calculated. An extended set of equations was also calculated for prediction of some tests with inclusion of nonlinear terms and the parameter years of abstinence from smoking. The reduction in variance which followed inclusion of tested parameters was moderate (20-60%). There were significant differences between these results and several previously published regression formulas.