Do asbestos-related pleural plaques on HRCT scans cause restrictive impairment in the absence of pulmonary fibrosis?

Abstract

Background It is uncertain whether isolated pleural plaques cause functional impairment. Objective To analyse the relationship between isolated pleural plaques confirmed by CT scanning and lung function in subjects with occupational exposure to asbestos. Methods The study population consisted of 2743 subjects presenting with no parenchymal interstitial abnormalities on the high-resolution CT (HRCT) scan. Asbestos exposure was evaluated by calculation of an individual cumulative exposure index (CEI). Each subject underwent pulmonary function tests (PFTs) and HRCT scanning. Variables were adjusted for age, smoking status, body mass index, CEI to asbestos and the centres in which the pulmonary function tests were conducted. Results All functional parameters studied were within normal limits for subjects presenting with isolated pleural plaques and for those presenting with no pleuropulmonary abnormalities. However, isolated parietal and/or diaphragmatic pleural plaques were associated with a significant decrease in total lung capacity (TLC) (98.1% predicted in subjects with pleural plaques vs 101.2% in subjects free of plaques, p¼0.0494), forced vital capacity (FVC) (96.6% vs 100.4%, p<0.001) and forced expiratory volume in 1 s (FEV 1 ) (97.9% vs 101.9%, p¼0.0032). In contrast, no significant relationship was observed between pleural plaques and FEV 1 /FVC ratio, forced expiratory flow at 25e75% FVC and residual volume. A significant correlation was found between the extent of pleural plaques and the reduction in FVC and TLC, whereas plaque thickness was not related to functional impairment. Conclusions The results show a relationship between isolated parietal and/or diaphragmatic pleural plaques and a trend towards a restrictive pattern, although the observed decrease in FVC and TLC is unlikely to be of real clinical relevance for the majority of subjects in this series.

Quantification of pleural plaques by computed tomography and correlations with pulmonary function: preliminary study

“…But these PFT results are still within normal limits, it may not have a real clinical relevance for the subjects with decreased pulmonary function. Similarly, study by Clin et al (20) showed that patients with isolated pleural plaques and/or diaphragmatic pleural plaques exhibited significant decreases in total lung capacity, FVC and FEV 1 which showed a trend towards a restrictive pattern. However, they concluded that since PFT results were within normal limits, the PFT decreases were unlikely to be of clinical relevance.…”

Are pleural plaques an appropriate endpoint for risk analyses?

“…In summary, in the six cross-sectional studies of non-Libby populations that evaluated the association between pleural plaques and pulmonary function with adjustment for asbestos exposure (Broderick et al, 1992;Clin et al, 2011;Lilis et al, 1991;Miller et al, 1994;Oliver et al, 1988;Wang et al, 2001), results varied depending on the measure of lung function, with no consistent patterns of association with spirometric or symptom-based outcomes. Moreover, two studies did not distinguish LPT from DPT (Miller et al, 1994;Wang et al, 2001), only one used highresolution computed tomography to detect LPT (Clin et al, 2011) and all six were susceptible to residual confounding by asbestos exposure and occult parenchymal fibrosis.…”

“…Numerous studies have examined the dose-or exposureresponse relation for pleural plaques (Bar-Shai et al, 2012;Boffetta, 1998;Clin et al, 2011;Eisenhawer et al, 2014;Ehrlich et al, 1992;Finkelstein & Vingilis, 1984;Hosoda et al, 2008;Jakobsson et al, 1995;Järvholm, 1992;Karjalainen et al, 1994;Lockey et al, 2015;Mastrangelo et al, 2009;McDonald et al, 1986;Moolgavkar et al, 2014;Paris et al, 2008Paris et al, , 2009Rohs et al, 2008;Sandén & Järvholm, 1986;Shepherd et al, 1997;Soulat et al, 1999;Van Cleemput et al, 2001). Results differ among these studies, 6 but exposure variables found relevant in one or more studies include time since first exposure (TSFE), age at first exposure (Jones, 1997), type (Hillerdal, 1997;Jones, 1997;Sandén & Järvholm, 1986) and dimensions of fiber (Hillerdal, 1997;Jones, 1997), lung fiber burden (Karjalainen et al, 1994;Roberts, 1971), duration of exposure, intensity of estimated asbestos exposure and cumulative exposure (measured in various ways).…”

Localized pleural thickening: Smoking and exposure to Libby vermiculite

“…4 LPT is associated with constricting pain 5,6 and reduced lung function. 7,8 Libby amphibole asbestos (LAA) is a mixture of amphibole fibers identified in the Rainy Creek complex and present in ore from the vermiculite mine near Libby, MT, USA. 9 Epidemiological studies of worker cohorts in Libby, MT, USA, 10,11 and Marysville, OH, USA, 12,13 exposed to LAA fibers indicate increased risk of radiographic abnormalities, and that the latency period for development of radiographic abnormalities may be relatively short (median latency of 8.6 years for pleural plaques in retrospective investigation of serial radiographs).…”