The natural course of lung function decline in asbestos exposed subjects with pleural plaques and asbestosis

Our plain-English summary of The natural course of lung function decline in asbestos exposed subjects with pleural plaques and asbestosis, by M. Barnikel, P.M. Million, H. Knoop, et al (Respiratory Medicine, 2019).

The study

• Authors: M. Barnikel, P.M. Million, H. Knoop, J. Behr
• Journal: Respiratory Medicine
• Published: 2019;154:82-85
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Unlabelled: While there is a good knowledge of the natural course of lung function in interstitial lung diseases (ILD) like idiopathic lung fibrosis (IPF), many ambiguities remain in patients with asbestosis. Therefore, we evaluated the change in lung function in asbestos exposed subjects with pleural plaques and asbestosis and analysed corresponding morphology of computer tomography of the thorax.

Methods: 93 asbestos exposed subjects with pleural plaques and asbestosis were analysed retrospectively at the Klinikum Bergmannsheil of the Ruhr-University of Bochum. Parameters of lung function were obtained at least twice and annual changes of FVC, TLC and DLCOsb were calculated. In addition, we assessed the predominant pattern in high-resolution computer tomography of the thorax (HRCT) and differentiated three phenotypes: p (pleural) -type, f (fibrosis) -type and m (mixed) -type.

Results: FU data are available in 56/93 (60.2%) patients. The annual deterioration (Mean ± SEM) of FVC is -31.46 ± 17.34 ml, of TLC -55.55 ± 25.67 ml, of DLCOsb -0.38 ± 0.07 mmol/min/kPa and of DLCOva -0.05 ± 0.01 mmol/min/kPa/L. A categorical change of FVC > -100 ml was found in 12/56 (21.4%) and 18/56 (32.1%) patients showed an annual loss of TLC > -100 ml. The greatest annual decline of FVC was observed in patients with the fibrotic phenotype on HRCT (-76.76 ± 66.43 ml) and the mixed phenotype (-81.52 ± 24.79 ml), while the pleural phenotype was less affected (-10.52 ± 25.07 ml).

Conclusion: More than 20% of our cohort have a progressive disease with an annual loss of FVC > -100 ml. Patients with the fibrotic-phenotype or mixed-phenotype on HRCT are particularly at risk.

Copyright © 2019. Published by Elsevier Ltd.

In plain English

This retrospective study reviewed 93 people in Bochum, Germany, with pleural plaques and asbestosis officially recognized as an occupational disease. The authors measured how breathing tests changed in the 56 patients who had at least two follow-up tests (mean follow-up 6.3 years). They also sorted CT scans by whether pleural plaques, lung scarring (fibrosis), or a mix of both predominated. On average, forced vital capacity (FVC, the amount of air that can be breathed out) fell by about 31 ml per year. Twelve of the 56 patients (21.4%) lost more than 100 ml of FVC per year, including 4 who lost more than 200 ml. FVC fell fastest in the fibrosis-type and mixed-type groups and least in the pleural-type group, but the authors reported no statistically significant differences. The authors concluded that more than 20% of the 56 patients with follow-up had progressive disease, and that those with fibrotic or mixed CT patterns were particularly at risk. They noted that the study was retrospective, small and from one center, and that it did not quantify each patient's asbestos exposure.

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: Retrospective, single-center observational study with descriptive statistics only
• Who was studied: 93 asbestos-exposed subjects with pleural plaques and asbestosis, all officially accepted as having asbestosis as an occupational disease (German occupational disease ordinance number 4103), analysed at the Klinikum Bergmannsheil of the Ruhr-University of Bochum, Germany. 56 of the 93 (60.2%) had at least two follow-up lung function tests. Study dates were not given.
• Exposure: Asbestos exposure judged sufficient to cause the disease by a specialist in occupational medicine. Fiber types, jobs and exposure levels were not reported or quantified.
• Main results:
  • Among patients with follow-up, the mean follow-up period was 6.3 years, totalling 352 patient-years.
  • Mean annual decline among the 56 patients with follow-up (mean plus or minus standard error): FVC −31.46 ± 17.34 ml (Table 2 prints −31.36), TLC −55.55 ± 25.67 ml, DLCOsb −0.38 ± 0.07 mmol/min/kPa.
  • 44 of 56 patients (78.6%) showed stable or slowly progressive disease, with an annual FVC loss of 100 ml or less.
  • 12 of 56 patients (21.4%) lost more than 100 ml of FVC per year; 4 of 56 (7.1%) lost more than 200 ml per year.
  • For total lung capacity (TLC), 18 of 56 patients (32.1%) lost more than 100 ml per year, including 10 of 56 (17.9%) who lost more than 200 ml per year.
  • Among all patients, CT patterns were pleural-type in 53%, fibrosis-type in 11%, mixed-type in 30%, and indeterminate in 6%.
  • Annual FVC decline by CT pattern: fibrotic type −76.76 ± 66.43 ml, mixed type −81.52 ± 24.79 ml, pleural type −10.52 ± 25.07 ml.
  • The differences between CT pattern groups were not statistically significant.
• The authors' conclusion: The authors concluded that more than 20% of the patients with at least two follow-up lung function tests (12 of 56) had progressive disease (annual FVC loss of more than 100 ml), and that patients with a fibrotic or mixed CT pattern were particularly at risk.
• Limitations the authors state:
  • Retrospective design, with its inherent limitations and biases
  • Individual asbestos exposure levels were not quantified or analysed
  • Mortality could not be evaluated, because patients were not followed up for it
  • Single-center study with a relatively small cohort of 56 patients with follow-up
  • Subgroups were small, so only descriptive statistics were provided

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis, Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Pleural Plaques, Interstitial Lung Disease, Idiopathic, Fibrosis, Thorax, High-Resolution CT (HRCT).

Related studies

• Pleural plaques and lung function in the Marysville worker cohort: a re-analysis — K. Zu, G. Tao, et al. (2016)
• Abnormal pulmonary function associated with diaphragmatic pleural plaques due to exposure to asbestos — K.H. Kilburn, R.H. Warshaw (1990)
• Prevalence of anti-nuclear autoantibodies in subjects exposed to natural asbestiform fibers: a cross-sectional study — C. Ledda, R. Caltabiano, et al. (2018)
• Coated and uncoated lung mineral fibres in subjects with and without pleural plaques at autopsy — A. Andrion, D. Bellis, et al. (1984)
• Asbestos-related lesions of the pleura: parietal plaques compared to diffuse thickening studied with chest roentgenography, computed tomography, lung function, and gas exchange — G. Hillerdal, P. Malmberg, et al. (1990)
• Asbestos-related pleural plaques and lung function — L.C. Oliver, E.A. Eisen, et al. (1988)

Browse more research in Respiratory Medicine, or return to medical research.