ABSTRACT BACKGROUND: Multiple studies have investigated the relationship between asbestos-related pleural plaques (PP) and lung function with disparate and inconsistent results. Most use chest radiographs to identify PP and simple spirometry to measure lung function. High resolution computerized tomography (HRCT) improves the accuracy of PP identification. Complete pulmonary function testing (PFT), including spirometry, lung volumes and diffusion capacity (DLCO), provides a more definitive assessment of lung function. The goal of this study was to determine the effect of PP on lung function in Libby vermiculite miners using HRCT and complete PFT.
METHODS: The results of HRCT and complete PFT performed between January 2000 and August 2012 were obtained from medical records of 166 Libby vermiculite miners. Multivariate regression analyses with Tukey multivariate adjustment was used to assess statistical associations between the presence of PP and lung function. Adjustments were made for age, BMI, smoking history, duration of employment and years since last occupational asbestos exposure.
RESULTS: Nearly 90% of miners (n=149) had evidence of PP on HRCT. No significant differences in spirometry results, lung volumes, or DLCO were found between miners with PP alone and miners with normal HRCT studies. Miners with both interstitial fibrosis and the presence of PP had a significantly decreased total lung capacity in comparison to miners with normal HRCT studies (p=0.03). Age, cumulative smoking history, and BMI were significant covariates that contributed to abnormal lung function.
CONCLUSION: Asbestos-related pleural plaques alone have no significant effect on lung function in Libby vermiculite miners.