Lung function values in healthy non-smoking urban adults in iran

BACKGROUND: The values of lung function tests (LFTs) are dependent on height, age, and sex. In addition, there is evidence of LFT variation in different ethnic groups. OBJECTIVE: We have therefore derived prediction equations for LFTs from a healthy, non-smoking, urban adult population in the city of Mashhad (northeast Iran). METHODS: Predicted equations for normal lung function have been derived from 572 healthy, non-smoking subjects including 326 men (height 154-195 cm) and 246 women (height 144-174 cm) aged 18-65 years. The subjects underwent measurement of spirometric flow and volume. The following variables were measured: forced vital capacity (FVC), forced expiratory volume in 1 s (FEV(1)), maximal mid-expiratory flow (MMEF), peak expiratory flow (PEF) and maximal expiratory flow at 75, 50 and 25% of the FVC (MEF(75), MEF(50), and MEF(25), respectively). Regression analysis using height and age as independent variables was applied to provide predicted values for both sexes. RESULTS: There was a negative correlation between each lung function and age. The largest negative correlations were found for FEV(1) and FVC in men and women, respectively. All parameters correlated positively with height; the largest positive correlation was observed for FVC in both sexes. Comparison of LFTs derived from the equations of the present study showed significant differences with those of several previous studies. CONCLUSION: In this study, a set of LFT reference values and prediction equations for both sexes have been derived using a relatively large, healthy, non-smoking Iranian, adult population which was different from several other prediction equations.