SPIROMETRIC STANDARDS FOR HEALTHY ADULT LIFETIME NONSMOKERS IN AUSTRALIA

The aim of this study was to develop suitable spirometric prediction e quations for asymptomatic Caucasian adults in the Australian populatio n, These equations were compared with those of previous studies and co nstants were presented which, when associated with the prediction equa tions, permitted the calculation of 5% tolerance intervals for lung fu nction. The 1,302 subjects (aged 18-78 yrs) who underwent pneumotachog raph spirometry, using techniques recommended by the American Thoracic Society, were a sample from metropolitan Adelaide, South Australia, T he variables recorded were sex, age, height, mass, forced expiratory v olume in one second (FEV1), forced vital capacity (FVC), peak expirato ry flow rate (PEFR), forced mid-expiratory flow (FEF25-75%) and FEV1/F VC ratio. Complete data were obtained for 614 females and 621 males, b ut the sample was reduced to 249 females and 165 males when only lifet ime nonsmokers with no adverse bronchial symptoms were selected, Predi ction equations of normal lung function were obtained from the reduced sample by multiple regression, with age, height and functions of both age and height as predictors, The derived equations did not differ si gnificantly from the majority of previously reported equations and wer e generally superior in their ability to predict the lung function of the asymptomatic ex-smokers who were part of the original sample, Anal ysis of the sensitivity, specificity and predictive power of 5% tolera nce limits for the presence of symptoms revealed the important roles o f FEV1, FEV1/FVC and FEF25-75% in diagnostic testing. The present pred iction equations are recommended for use on the Australian population and on populations with similar Caucasian characteristics.