Abnormal pulmonary function associated with diaphragmatic pleural plaques due to exposure to asbestos

Our plain-English summary of Abnormal pulmonary function associated with diaphragmatic pleural plaques due to exposure to asbestos, by K.H. Kilburn, R.H. Warshaw (British Journal of Industrial Medicine, 1990).

The study

• Authors: K.H. Kilburn, R.H. Warshaw
• Journal: British Journal of Industrial Medicine
• Published: 1990;47(9):611-4
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 003762).

Abstract

Pulmonary function was measured in 79 men with diaphragmatic pleural plaques (DPP) as the only abnormality characteristic of asbestos disease on chest radiographs. They were selected from 4572 construction and shipyard workers exposed to asbestos. Abnormalities of pulmonary function in 21 non-smokers and 43 current smokers were compared with referent values adjusted for height, age, and duration of cigarette smoking. In the non-smokers, flows (FEV1) FEF75-85 and FEV1/FVC) were reduced and TGV and RV/TGV were raised. Current smokers had similar significant reductions. Thus by contrast with some current opinion that plaques are "an index only of past asbestos exposure," workers with plaques, even limited to the diaphragm, have functional impairment typical of pulmonary asbestosis. This suggests that they have pulmonary asbestosis, which is below the threshold of radiographic recognition.

In plain English

This study measured lung function in 79 men whose chest x-rays showed plaques on the diaphragm as the only sign of asbestos disease. They were selected from 4572 asbestos-exposed men at 20 United States sites, most of them members of boilermakers', pipefitters', metal, or chemical unions. Their mean age was just over 60, with over 30 years of asbestos exposure. Results for 21 non-smokers and 43 current smokers were compared with Michigan men from a random population sample, as percentages of predicted values adjusted for height, age and years of smoking. Fifteen ex-smokers were not analysed further. Among non-smokers, men with plaques had an FEV1 of 92.1% of predicted versus 99.2% in referents, and more air trapping. Their FVC did not differ significantly. Current smokers with plaques also had reduced flow measures and more air trapping, although their FVC and FEV1 differences were not statistically significant. The authors concluded that diaphragmatic plaques were associated with obstructive limitation of expiratory airflow, and suggested these men have pulmonary asbestosis below the threshold of x-ray recognition.

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 comparison of lung function in asbestos-exposed men with diaphragmatic pleural plaques against referents from a Michigan population sample, using t tests
• Who was studied: 79 men with diaphragmatic plaques as the only radiographic sign of asbestos disease, selected from 4572 men at 20 United States sites, mostly union members. 21 non-smokers and 43 current smokers were analysed; 15 ex-smokers were not. The mean age was just over 60. Referents were 119 non-smoking and 167 currently smoking men from a stratified random population sample of Michigan.
• Exposure: Occupational asbestos exposure (fiber type not stated). Most men were members of boilermakers', pipefitters', metal, or chemical unions. Study criteria were 15 or more years since first exposure and five or more years of exposure. The mean exposure was over 30 years.
• Main results:
  • In the non-smokers, men with plaques (n=21) had a lower FEV1 than non-smoking referents (n=119): 92.1 versus 99.2 percent of predicted, p 0.015.
  • In the non-smokers, men with plaques had a lower FEF75-85 than referents: 72.3 versus 102.1 percent of predicted, p 0.0014.
  • In the non-smokers, men with plaques had a higher RV/TGV than referents: 46.8 versus 30.3, p 0.0001.
  • In the non-smokers, men with plaques had a higher TGV than referents: 110.8 versus 100.1 percent of predicted, p 0.0009.
  • In the non-smokers, differences were not significant for mid flows (FEF25-75: 92.1 versus 100.1, p 0.4) or FVC (96.0 versus 99.0, p 0.3).
  • In current smokers, men with plaques (n=43) had a lower FEV1/FVC than smoking referents (n=167): 72.3 versus 77.4, p 0.0001.
  • In current smokers, men with plaques had a lower FEF75-85 than referents: 83.2 versus 106.8, p 0.0001.
  • In current smokers, men with plaques had a higher RV/TGV than referents: 46.0 versus 34.0, p 0.0001.
  • In current smokers, differences in FVC (93.5 versus 95.8, p 0.4) and FEV1 (93.1 versus 95.2, p 0.2) were not statistically significant in the table.
  • Because thoracic gas volume was increased, the authors found no evidence of restrictive impairment.
• The authors' conclusion: The authors concluded that diaphragmatic pleural plaques were associated with limitation of expiratory flow, an obstructive lesion located in the small airways. They suggested that these men have pulmonary asbestosis below the threshold of radiographic recognition.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Plaques, Chest X-Ray, FEV1, FEV1/FVC Ratio, Asbestos Exposure, Diaphragm, Asbestosis.

Related studies

• Abnormal lung function associated with asbestos disease of the pleura, the lung, and both: a comparative analysis — K.H. Kilburn, R.H. Warshaw (1991)
• Do asbestos-related pleural plaques on HRCT scans cause restrictive impairment in the absence of pulmonary fibrosis? — B. Clin, C. Paris, et al. (2011)
• Systematic review of pleural plaques and lung function — L.E. Kerper, H.N. Lynch, et al. (2015)
• The natural course of lung function decline in asbestos exposed subjects with pleural plaques and asbestosis — M. Barnikel, P.M. Million, et al. (2019)
• Pleural plaques and lung function in the Marysville worker cohort: a re-analysis — K. Zu, G. Tao, et al. (2016)
• Risk and significance of chest radiograph and pulmonary function abnormalities in an elderly cohort of former nuclear weapons workers — M.A. Mikulski, P.G. Hartley, et al. (2011)

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