Prediction equations for pulmonary function values in healthy children in Mashhad city, North East Iran

Background: Pulmonary function tests (PFTs) are used in assessing physiological to clinical status of the respiratory system, which is expressed as a percentage of predicted values. Predicted PFTs values are varies in different ethnics. Predicted PFTs values were studied in a sample of Iranian children. Materials and Methods: Prediction equations for PFTs were derived from urban children in the city of Mashhad (northeast Iran). Regression analysis using height and age as independent variables was applied to provide predicted values for both sexes. PFT values were measured in 414 healthy children (192 boy and 222 female, aged 4-10 years). Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), maximal mid-expiratory flow (MMEF), peak expiratory flow (PEF), MEF at 75%, 50% and 25% of the FVC (MEF75, MEF50 and MEF25 respectively) were measured. Results: There were positive correlations between each pulmonary function variable with height and age. The largest positive correlations were found for FVC (r = 0.712, P < 0.0001) and FEV1 (r = 0.642, P < 0.0001) in boys and girls respectively with height and for PEF (0.698, P < 0.0001) and MEF (r = 0.624, P < 0.0001) with age. Comparison of PFTs derived from the equations of the present study showed significant differences with those of several previous studies (P < 0.001 for most cases). Conclusion: A set of PFT reference values and prediction equations for both sexes has been derived using relatively large, healthy, Iranian children for the first time, which the generated results were differ from several prediction equations.