Is forced oscillation technique useful in the diagnosis of occupational asthma?

ABSTRACT

OBJECTIVE: The aim of the study was to determine whether the forced oscillation technique (FOT), which does not require active cooperation, may be useful to assess bronchial responsiveness in patients with suspected occupational asthma (OA). METHODS: Changes in resistances evaluated by FOT, and DeltaFEV1 measured during methacholine challenge test were compared in 77 adults referred for suspected OA. Spearman correlations and ROC curves were used. RESULTS: R0 at the final dose of methacholine (R0hmd) and DeltaR0 were strongly correlated with DeltaFEV1 (p < 0.001). The ROC curves showed that R0hmd >or= 240% predicted was the best cut-off value to discriminate subjects with OA from nonasthmatic subjects (sensitivity 80%, specificity 76%). CONCLUSION: FOT can be proposed as an alternative method for the assessment of bronchial responsiveness in subjects with suspected OA, unable to correctly perform forced expiratory maneuvers.