Lung function not affected by asbestos exposure in workers with normal Computed Tomography scan

Our plain-English summary of Lung function not affected by asbestos exposure in workers with normal Computed Tomography scan, by C. Schikowsky, M.K. Felten, C. Eisenhawer, et al (American Journal of Industrial Medicine, 2017).

The study

• Authors: C. Schikowsky, M.K. Felten, C. Eisenhawer, M. Das, T. Kraus
• Journal: American Journal of Industrial Medicine
• Published: 2017;60(5):422-431
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: It has been suggested that asbestos exposure affects lung function, even in the absence of asbestos-related pulmonary interstitial or pleural changes or emphysema.

Methods: We analyzed associations between well-known asbestos-related risk factors, such as individual cumulative asbestos exposure, and key lung function parameters in formerly asbestos-exposed power industry workers (N = 207) with normal CT scans. For this, we excluded participants with emphysema, fibrosis, pleural changes, or any combination of these.

Results: The lung function parameters of FVC, FEV1, DLCO/VA, and airway resistance were significantly associated with the burden of smoking, BMI and years since end of exposure (only DLCO/VA). However, they were not affected by factors directly related to amount (eg, cumulative exposure) or duration of asbestos exposure.

Conclusions: Our results confirm the well-known correlation between lung function, smoking habits, and BMI. However, we found no significant association between lung function and asbestos exposure.

© 2017 Wiley Periodicals, Inc.

In plain English

This study asked whether past asbestos exposure was linked to poorer lung function in workers whose CT scans showed no asbestos-related changes and no emphysema. The authors analysed 207 male power industry workers with past asbestos exposure in Germany, all tested at one centre in Aachen. Exposure was estimated from job histories. It averaged 49.0 fiber years (range 0.1 to 844.9) over an average of 21.4 years, and the article does not name the fiber types. The authors measured breathing volumes (FVC, FEV1), gas transfer (DLCO/VA) and airway resistance. Smoking (pack years) and body mass index were significantly associated with all four measures. Current smokers had significantly lower FVC, FEV1 and DLCO/VA than never-smokers and ex-smokers. No measure of the amount or duration of asbestos exposure was significantly associated with lung function, including when never-smokers, ex-smokers and smokers were analysed separately. The authors concluded they found no evidence that asbestos exposure without CT abnormalities affected these measures. They noted possible selection bias, and that exposure estimates were not based on fiber measurements at the actual workplaces.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Cross-sectional analysis of workers from a company asbestos health surveillance program, using univariate and multivariate linear regression, analysis of variance by smoking status, and regression stratified by smoking status
• Who was studied: 207 male formerly asbestos-exposed workers (the surveillance program enrolled both active and former employees) of a major German electrical power provider. All had CT scans (MDCT) showing no emphysema and no asbestos-related lung or pleural changes. All had lung function testing at the Institute for Occupational and Social Medicine, RWTH Aachen University. Examinations ran from March 2002 to the end of 2013. Of the participants with MDCT whose lung function was tested at that centre, 652 were excluded for emphysema (79), asbestos-related changes (296) or both (277).
• Exposure: Occupational asbestos exposure in the power industry; fiber types not named. Cumulative exposure was estimated from job titles, main tasks and self-reported exposure periods using workplace air monitoring data. The mean was 49.0 fiber years (range 0.1 to 844.9) over a mean exposure duration of 21.4 years. Smoking (mean 34.4 pack years among smokers and ex-smokers) and body mass index were also analysed.
• Main results:
  • In all 207 workers, smoking (pack years) and body mass index had a significant effect on all four lung function measures (FVC, FEV1, DLCO/VA, airway resistance) in univariate analysis.
  • In all 207 workers, none of the factors related to the duration or amount of asbestos exposure (cumulative exposure in fiber years, exposure duration) was significantly associated with any of the lung function measures, in either univariate or multivariate analysis.
  • In univariate analysis, time since end of asbestos exposure was significantly associated with DLCO/VA. The authors suggested this and the age association may reflect inaccurate age-adaptation of the DLCO/VA reference values.
  • Current smokers (n = 43) had significantly lower mean values than never-smokers (n = 53) and ex-smokers (n = 111) for FVC (92.3% vs 101.7% and 99.3% of reference), FEV1 (87.7% vs 100.6% and 96.6%) and DLCO/VA (99.4% vs 114.6% and 114.0%). The three smoking groups did not differ significantly in asbestos-related factors.
  • When never-smokers, ex-smokers and smokers were analysed separately, no significant association was found between asbestos exposure factors and lung function in any group.
  • Mean FVC was 98.5% and mean FEV1 was 95.8% of age-adjusted reference values. 74 of 207 participants had lung function classified as abnormal, mostly because of raised airway resistance (67 participants). The authors related this to about three quarters of the group being former or current smokers.
• The authors' conclusion: The authors concluded they found no evidence that asbestos exposure without matching CT abnormalities had any effect on FVC, FEV1, DLCO/VA or airway resistance. In their view, asbestos dust seems an unlikely cause of clinically relevant lung function impairment when CT shows no characteristic abnormalities. They said the slightly reduced mean FVC and FEV1 were fully explained by smoking.
• Limitations the authors state:
  • The careful selection of only CT-normal participants might have introduced selection bias.
  • Asbestos exposure estimates were not based on objective fiber measurements at participants' actual workplaces.
  • Analysing smoking subgroups separately reduced statistical power.
  • The reference values used for DLCO/VA may not be suitably adapted for age.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Interstitial, Emphysema, CT Scan, Fibrosis, FEV1, Diffusing Capacity (DLCO), Cumulative Exposure.

Related studies

• Commentary to the article lung function not affected by asbestos exposure in workers with normal Computed Tomography scan, by Schikowsky, Felten, et al., 2017 — X. Baur, B. Terracini, et al. (2018)
• High resolution computed tomography and lung function in asbestos-exposed workers with normal chest radiographs — C.A. Staples, G. Gamsu, et al. (1989)
• Findings from high resolution computed tomography of the lung and pleura of symptom free workers exposed to amosite who had normal chest radiographs and pulmonary function tests — S. Neri, A. Antonelli, et al. (1994)
• Pulmonary function, smoking habits, and high resolution computed tomography (HRCT) early abnormalities of lung and pleural fibrosis in shipyard workers exposed to asbestos — S. Neri, P. Boraschi, et al. (1996)
• Smoking, occupational risk factors, and bronchial tumor location: a possible impact for lung cancer computed tomography scan screening — M. Gonzalez, J.M. Vignaud, et al. (2012)
• Do asbestos-related pleural plaques on HRCT scans cause restrictive impairment in the absence of pulmonary fibrosis? — B. Clin, C. Paris, et al. (2011)

Browse more research in American Journal of Industrial Medicine, or return to medical research.