Background Among asbestos-exposed individuals, abnormal spirometry is usually associated with parenchymal abnormalities or diffuse pleural thickening. Localised pleural thickening (LPT), the most common abnormality associated with asbestos exposure, is typically thought to be a marker of exposure with little clinical consequence. Our objective was to determine if abnormal spirometry is associated with LPT independent of other abnormalities, using data from community-based screening conducted in Libby, Montana.
Methods Subjects were a subset of screening participants comprising persons with interpretable spirometry and chest radiograph results (n=6475). Chest radiographs were independently evaluated by two or three B readers, and participants were classified by mutually exclusive categories of spirometry outcome: normal, restriction, obstruction or mixed defect.
Results Restrictive spirometry was strongly associated with parenchymal abnormalities (OR 2.9; 95% CI 1.4 to 6.0) and diffuse pleural thickening (OR 4.1; 95% CI 2.1 to 7.8). Controlling for the presence of these abnormalities as well as age, smoking status and other covariates, restrictive spirometry was also associated with LPT (OR 1.4; 95% CI 1.1 to 1.8). The risk of restrictive spirometric findings correlated with the severity of LPT.
Conclusions In this large community-based screening cohort, restrictive spirometry is significantly associated with LPT, indicating that this abnormality may result in lung function impairment. Physicians treating patients exposed to Libby amphibole should be aware that LPT may have functional consequences.
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Roles of authors: Guarantors of the integrity of the entire study: TCL, ML and EBG. Study concepts/study design or data acquisition or data analysis: all authors. Manuscript drafting or manuscript revision for important intellectual content: all authors. Manuscript final version approval: all authors. Literature search: TCL and VCA. Clinical studies: EBG. Statistical analyses: ML and TCL. Manuscript editing: all authors.
Funding This study was financed by intramural funds from the US Department of Health and Human Services 200 Independence Avenue, S.W. Washington, D.C. 20201.
Competing interests None.
Patient consent Obtained.
Ethics approval The study was approved by Centers for Disease Control and Prevention.
Provenance and peer review Not commissioned; externally peer reviewed.
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