Abstract

Age may have a different contribution to normal lung function values in those aged less than 25 years, as compared to older individuals. We report regression equations predicting ventilatory parameters in this age group, as none have been reported from Pakistan. The study was conducted on students of King Edward Medical College Lahore, Pakistan. Participants had never smoked and reported no respiratory symptoms. In addition to anthropometric data, forced expiratory volume in 1 sec (FEV1), forced vital capacity (FVC), peak expiratory flow (PEF) and forced expiratory flow at 50% of FVC (FEF50) were measured. Equations predicting normal values of these parameters were derived using SPSS (Chicago, Illinois, U.S.A.) P < or = 0.05 was treated as statistically significant. Of the students, 519 took part in the study. All four parameters correlated significantly (P < 0.001) and positively with height. FEF50 had a negative correlation with age in both sexes (P < 0.05). The correlation of other parameters with age was variable and not statistically significant. On multiple regression, height featured as an independent predictor in equations for all parameters. The contribution of age as an independent predictor of ventilatory function was, once again, variable. Independent variables were retained in the raw form as their transformation did not improve the goodness of fit of the derived equations. Only height and age emerged as independent predictors of ventilatory function. Values derived from the equations presented in this study were less than those for height and age matched white Caucasians. Such differences were greater than the 'Asian correction factors'.