Is Forced Oscillation Technique Useful in the Diagnosis of Occupational Asthma?

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 △FEV1 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 (ROhmd) and △R0 were strongly correlated with △FEV1 (p < 0.001). The ROC curves showed that ROhmd ≥ 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.