VALIDITY OF ECSC PREDICTION EQUATIONS FOR SPIROMETRIC INDEXES IN DUTCH CONSCRIPTS

A study was performed to determine whether prediction equations issued by the European Community for Steel and Coal (ECSC) and the European Respiratory Society (ERS) fit spirometric data in young adult males. The study comprised 246 randomly selected Dutch conscripts, who participated in the study on the basis of informed consent. A questionnaire was used to assess respiratory symptoms and smoking habits. Maximal expiratory flow-volume curves were obtained with a rolling seal spirometer, and summary statistics selected according to ECSC/ERS recommendations. In addition, standing height and body weight were obtained. We analysed the data of 100 conscripts of European descent, with no history of respiratory symptoms. They were all life-long nonsmokers. Their mean (SD) age was 18 (0.12) yrs (range 17.9-19.0 yrs), with a mean (SD) standing height of 1.84 (0.06) m (range 1.68-2.00 m). The data for forced vital capacity (FVC), forced expiratory volume in one second (FEV(1)) and maximal midexpiratory flow (MMEF) agreed well with ECSC predictions; 95% confidence intervals (95% CI) of differences between measured and predicted values were -0.174 to 0.044 l, -0.012 to 0.174 l.s(-1) and -0.114 to 0.302 l.s(-1), respectively. Peak expiratory flow was systematically larger than predicted, as was FEV(1)%FVC (95% CI 0.74 to 1.31 l.s(-1) and 2.50 to 5.24%, respectively), due to the intercept being inappropriate. The residual standard deviation in the conscripts was somewhat less than in the ECSC/ERS predictions equations, except for peak expiratory now (PEF). The percentages of observations below the predicted lower limit were 9% for FVC1 5% for FEV(1), 2% for FEV(1)%FVC, 2% for PEF, and 4% for MMEF. We conclude that the ECSC/ERS recommendations are satisfactory for FEV(1), FVC and MMEF. However, FEV(1)%FVC and PEF are systematically higher than predicted, but this does not preclude the use of prediction equations for diagnostic and discriminatory purposes.