Early diagnosis of respiratory abnormalities in asbestos-exposed workers by the forced oscillation technique

Abstract

Background: The current reference test for the detection of respiratory abnormalitiesin asbestos-exposed workers is spirometry. However, spirometry has several shortcomings that greatly affect the efficacy of current as bestos control programs. The forced oscillation technique (FOT) represents the current state-of-the-art technique in the assessment of lung function. This method provides a detailed analysis of respiratory resistance and reactance at different oscillatory frequencies during tidal breathing. Here, we evaluate the FOT as an alternative method to standard spirometry for the early detection and quantification of respiratory abnormalitiesin asbestos-exposed workers. Methodology/Principalfindings: Seventy-two subjects were analyzed. The control group was composed of 33 subjects with a normal spirometricexam who had no history of smoking or pulmonarydisease. Thirty-nine subjects exposed to asbestos were also studied, including 32 volunteers in radiological category0/0 and 7 volunteers with radiological categories of 0/1 or 1/1. FOT data were interpreted using classical parameters as well as integer (InOr) and fractional-order (FrOr) modeling. The diagnostic accuracy was evaluated by investigating the area under the receiver operating characteristic curve (AUC). Exposed workers presented increased obstruction (resistance p<0.001) and a reduced compliance (p<0.001), with a predominance of obstructive changes. The FOT parameter changes were correlated with the standard pulmonaryfunction analysis methods (R = -0.52, p<0.001). Early respiratory abnormalitieswere identified with a high diagnostic accuracy (AUC = 0.987) using parameters obtained from the FrOr modeling. This accuracy was significantly better than those obtained with classical (p<0.001) and InOr (p<0.001) model parameters. Conclusions: The FOT improved our knowledge about the biomechanical abnormalitiesin workers exposed to asbestos. Additionally, a high diagnostic accuracy in the diagnosis of early respiratory abnormalities in asbestos-exposed workers was obtained. This makes the FOT particularly useful as a screening tool in the context of asbestos control and elimination. Moreover, it can facilitate epidemiological research and the longitudinal follow-up of asbestos exposure and asbestos-related diseases.