MEASUREMENT OF BRONCHIAL RESPONSIVENESS BY FORCED OSCILLATION TECHNIQUE IN OCCUPATIONAL EPIDEMIOLOGY

The performance of the forced oscillation technique (FOT) in the asses sment of bronchial responsiveness on the methacholine challenge test w as compared with that of forced expiratory volume in one second (FEV1) in 119 active workers with normal baseline pulmonary function. Change s in resistance (DELTAR0%), frequency dependence of resistance (DELTAP ) and resonant frequency (DELTAF%) determined by the FOT were compared to the DELTAFEV1%. Receiver operating characteristic (ROC) curves wer e established to determine values of the changes in FOT parameters whi ch corresponded to the best sensitivity and specificity for classifyin g the subjects as hyperresponsive or nonresponsive on the methacholine challenge test. Significant correlations were observed between DELTAF EV1% and DELTAR0%, DELTAP and DELTAF% respectively. The ROC curves sho wed the following cut-off values of FOT parameters to be the best valu es for classifying the subjects according to the presence or absence o f 20% fall in FEV1: a 65% increase in R0 (sensitivity 75%; specificity : 76%); a decrease of 65x10(-3) hPa.l-1.s2 in P (sensitivity 58%; spec ificity 83%); a 50% increase in F (sensitivity 75%; specificity 62%). Our results suggest that the FOT is a useful test for assessment of br onchial hyperresponsiveness when compared to spirometry, and can be ap plied to epidemiological studies of a bronchial challenge test in norm al active working populations.