The relationship between respiratory impairment and asbestos-related pleural abnormality in an active work force

Our plain-English summary of The relationship between respiratory impairment and asbestos-related pleural abnormality in an active work force, by J. Bourbeau, P. Ernst, J. Chrome, et al (The American Review of Respiratory Disease, 1990).

The study

• Authors: J. Bourbeau, P. Ernst, J. Chrome, B. Armstrong, M.R. Becklake
• Journal: The American Review of Respiratory Disease
• Published: 1990;142(4):837-42
• Cited by: 68 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 003750).

Abstract

With the general improvement in environmental controls in workplaces where asbestos is used, an increasing number of workers are seen who exhibit isolated pleural plaques. The question as to whether these are associated with respiratory impairment independently of parenchymal disease remains unresolved. The question was reinvestigated using quantitative gallium-67 lung scanning to take into account early parenchymal change not evident on the chest radiograph. We carried out a cross-sectional study of 110 construction insulators all currently at work. Overall, 58.2% had pleural abnormality, 52.5% pleural plaques only, and 5.5% diffuse pleural thickening as assessed from the PA chest radiograph. Compared with those without, those with any pleural abnormality had a decrease in FEV1 and FVC on average of 222 and 402 ml (p less than 0.05), and those with isolated pleural plaques, a decrease on average of 200 and 350 ml (p less than 0.05), after taking into account age, height, smoking status, and the presence of parenchymal abnormality as assessed by chest radiography and gallium uptake. The complaint of dyspnea with strenuous activities was also significantly related to the width and extent of chest wall pleural thickening (p less than 0.05), independently of parenchymal disease. This study suggests that the most common radiographic findings in asbestos-exposed, isolated pleural plaques are associated with a significant reduction in FEV1 and FVC, which cannot be attributed to the presence of radiographic and subradiographic pulmonary fibrosis.

In plain English

This cross-sectional study examined 110 construction insulators aged 35 and older who were still at work, drawn from a Quebec insulators' union local. The authors asked whether asbestos-related pleural abnormality, especially isolated pleural plaques, is linked to poorer breathing apart from scarring of the lung tissue itself. Workers had chest X-rays, breathing and exercise tests, breathlessness questionnaires, and gallium-67 lung scans to detect early lung tissue changes not visible on X-ray. Overall, 58.2% had a pleural abnormality: 52.5% had pleural plaques only and 5.5% had diffuse pleural thickening. After accounting for age, height, smoking and lung tissue changes, workers with any pleural abnormality had two standard breathing measures (FEV1 and FVC) that were significantly lower on average, by 222 and 402 ml. Those with isolated plaques had values lower by 200 and 350 ml. Most differences in breathlessness were not statistically significant after adjustment. The authors concluded that isolated plaques were associated with reduced FEV1 and FVC that could not be attributed to lung fibrosis. They noted that studying only active workers likely minimized the effect.

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 study
• Who was studied: 110 currently employed construction insulators aged 35 years and older (110 of 129 eligible), members of Local 58 of the International Union of Frost and Heat Insulation and Asbestos Workers in Quebec. They were selected from workers tested in the authors' laboratory in Montreal in 1983-1984.
• Exposure: Occupational asbestos exposure as construction insulators. Fiber types are not specified. Years in the trade and years since first exposure were recorded and were reported as similar between workers with and without pleural abnormality.
• Main results:
  • Of the 110 insulators, 58.2% had any pleural abnormality, 52.5% had pleural plaques only, and 5.5% had diffuse pleural thickening on the PA chest radiograph.
  • Compared with workers without pleural abnormality, workers with any pleural abnormality had FEV1 and FVC lower on average by 222 and 402 ml (p less than 0.05). This was after adjusting for age, height, smoking and parenchymal abnormality on radiograph and gallium uptake.
  • Workers with isolated pleural plaques had FEV1 and FVC lower on average by 200 and 350 ml (p less than 0.05) after the same adjustments.
  • The largest deficit in resting lung function was related to costophrenic angle obliteration. FVC was 460 ml lower on average in workers with blunting of one costophrenic angle.
  • Breathlessness was more frequent in workers with pleural change, but most differences were not statistically significant after accounting for age, smoking and parenchymal abnormality.
  • For isolated pleural plaques taken as present or absent, the odds ratios for breathlessness were not statistically significant.
  • Breathlessness with major activities, such as walking up a steep hill, was significantly related to the extent of chest wall pleural thickening after adjustment.
  • No effect of pleural change on maximal oxygen consumption during exercise could be shown.
• The authors' conclusion: The authors concluded that isolated pleural plaques were associated with a significant reduction in FEV1 and FVC. In their view, this reduction could not be attributed to radiographic or subradiographic pulmonary fibrosis.
• Limitations the authors state:
  • Only active workers were examined, among whom health selection was likely to have minimized the size of the effect.
  • Assessment of pleural abnormality on radiographs has substantial between-reader and within-reader variability. The authors argued that random error of this kind would weaken, not explain, the observed relationship.
  • The PA chest radiograph detects only a small proportion of pleural abnormalities found at autopsy.
  • Some pleural thickening was seen as early as 10 years after first exposure, which suggested that some of it was due to fat. Adjusting for weight did not alter the estimated effect.
  • The study had limited power to show differences in breathlessness.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

Medical terms in this study, explained in our Lexicon: Pleural Plaques, Chest X-Ray, Insulator, Diffuse Pleural Thickening, FEV1, Dyspnea, Pleural Thickening, Pulmonary Fibrosis.

Related studies

• The relationship between respiratory impairment and asbestos-related pleural abnormality in an active work force — J.E. Cotes, B. King (1991)
• Pleural abnormality as a cause of impairment and disability — P. Ernst, J. Bourbeau, et al. (1991)
• Respiratory findings among millwright and machinery erectors: identification of health hazards from asbestos in place at work — A. Fischbein, J.C. Luo, et al. (1993)
• Between- and within-reader variability in the assessment of pleural abnormality using the ILO 1980 international classification of pneumoconioses — J. Bourbeau, P. Ernst (1988)
• Correlation between respiratory symptoms and pulmonary function in asbestos-exposed workers — C.A. Brodkin, S. Barnhart, et al. (1993)
• Radiographic abnormalities in asbestos insulators: effects of duration from onset of exposure and smoking. Relationships of dyspnea with parenchymal and pleural fibrosis — R. Lilis, A. Miller, et al. (1991)

Browse more research in The American Review of Respiratory Disease, or return to medical research.