Pleural plaques and lung function in asbestos-exposed workers free from pulmonary fibrosis

Background: Relationships between parietal pleural plaques and lung function impairment still remain controversial. Aims: This study analyses the relationships between isolated pleural plaques and lung function, among subjects occupationally exposed to asbestos. Methods: The study population consisted of 2,743 subjects included in a large-scale pilot screening program for asbestos-related diseases in four regions of France between 2003 and 2005. All had been occupationally exposed to asbestos, and were free of interstitial disease on high resolution chest computed tomography (HRCT). The asbestos exposure was assessed with calculation of an individual cumulative exposure index (CEI) taking into account all job periods for each subject. Each included subject benefited from pulmonary function tests (PFT) and HRCT was interpreted by a panel of expert radiologists in thoracic imaging. In both univariate and multivariate analysis, variables were adjusted on tobacco status, body mass index (BMI), CEI to asbestos and the center where PFT were made. Results: Isolated pleural plaques were associated with a significant decrease of TLC (p=0.049), FVC (p=0.001) and FEV1 (p=0.003). On the other hand, no significant relationship was observed between pleural plaques and FEV1/FVC ratio, FEF25-75% and RV. A significant correlation was found between the extent of pleural plaques and the reduction of FVC (p trend=0.0089) and TLC (p trend=0.0046). By contrast, thickness of pleural plaques was not related to any functional impairment. Conclusions: Our results are in favor of a relationship between isolated parietal and/or dipahragmatic pleural plaques and a trend to restrictive pattern.