Comparison of FEV(3), FEV(6), FEV(1)/FEV(3) and FEV(1)/FEV(6) with usual spirometric indices

Background and objective: Pulmonary function tests play an important role in the management of pulmonary diseases. One of the tests that are widely used is spirometry. Performing an acceptable spirometry manoeuvre according to the standards set by the American Thoracic Society/European Respiratory Society is difficult. The aim of this study was to compare forced expiratory volume in 3 s (FEV₃) and forced expiratory volume in 6 s (FEV₆) with forced vital capacity (FVC), and forced expiratory volume in 1 s FEV₁/FEV₃ and FEV₁/FEV₆ with FEV₁/FVC, in order to substitute the usual spirometric manoeuvres with manoeuvres that are easier to perform. Methods: In a cross‐sectional study, spirometry was performed for 588 subjects who were referred for occupational health evaluations. The accuracy of FEV₃, FEV₆, FEV₁/FEV₃ and FEV₁/FEV₆ was compared with that of FVC and FEV₁/FVC. Chi‐square tests and kappa tests were used to analyse the data. Results: Individuals with normal (n = 297) and abnormal spirometry (n = 291) were evaluated. The sensitivity, specificity, positive predictive value and negative predictive value of FEV₁/FEV₆, as compared with that of FEV₁/FVC for detecting obstruction, were 93.56, 99.32, 98.95 and 96.09, respectively. The sensitivity, specificity, positive predictive value and negative predictive value of FEV₆, as compared with that of FVC for detecting restriction, were 96.68, 98.65, 96.68 and 98.65, respectively. Conclusions: FEV₆ and FEV₁/FEV₆ can be used as surrogates for FVC and FEV₁/FVC, respectively, and these parameters showed acceptable sensitivity, specificity, positive predictive value and negative predictive value for occupational health evaluations.