The left-sided predominance of asbestos-related pleural disease

Our plain-English summary of The left-sided predominance of asbestos-related pleural disease, by H. Hu, L. Beckett, K. Kelsey, et al (The American Review of Respiratory Disease, 1993).

The study

• Authors: H. Hu, L. Beckett, K. Kelsey, D. Christiani
• Journal: The American Review of Respiratory Disease
• Published: 1993;148(4 Pt 1):981-4
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

In a series of 406 subjects with a diagnosis of asbestos-related pleural disease (ARPD), the left-right symmetry of radiographically diagnosed ARPD was assessed using the International Labour Organization (ILO) system for classifying radiographic abnormalities and three different statistical models for testing the degree of symmetry. The extent of chest disease was found to be greater on the left than on the right for a number of parameters of pleural disease, including the width and extent of localized pleural thickening, the extent of enface pleural thickening, and the extent of diaphragmatic and chest wall calcification. Current cigarette smoking significantly enhanced the observed asymmetry, with the most pronounced effect being in diaphragmatic calcification. Using a composite scale for each subject's pleural disease, the left side had 1.6 times more localized disease than did the right (p < 0.001). Asymmetry in one parameter was associated with asymmetry in another for a number of pairs. The most significant of these associations was between enface pleural thickening and chest wall calcification (Kendall's tau B = 0.42). The pathophysiologic mechanisms that explain these findings remain elusive and need further investigation.

In plain English

This study examined chest X-rays of 406 people with asbestos-related pleural disease (disease of the lining around the lungs) seen at a Massachusetts referral center for asbestos-exposed workers between July 1987 and July 1989. Most patients at the center had been exposed through shipyard and construction work. The authors compared the left and right sides of the chest using the International Labour Office X-ray classification. For five of nine pleural disease categories, disease was worse on the left more often than on the right. About 2.5 times as many subjects had more severe diaphragmatic calcification on the left as on the right, and about twice as many had greater extent of localized pleural thickening on the left. No category showed an excess on the right. The left-sided pattern in diaphragmatic calcification was strongest in current smokers and nearly symmetric in never smokers. The authors noted that the current and never smoker subgroups were too small for most results to be statistically significant. The authors concluded that their findings strongly support a left-sided predominance. They noted they could not test whether X-rays detect disease equally well on both sides.

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 left-right symmetry on chest radiographs from a clinical referral series, using statistical models for paired, ordinal data
• Who was studied: 406 patients with a diagnosis of asbestos-related pleural disease at the Massachusetts Respiratory Hospital Center for Occupational and Environmental Medicine, a regional referral center for asbestos-exposed workers. Data came from each patient's earliest visit between July 1, 1987 and July 1, 1989. There were 75 current smokers, 238 former smokers and 92 never smokers. 71 (18%) had parenchymal asbestosis.
• Exposure: Asbestos exposure, mostly through work in the shipyard and construction trades. Fiber types and doses were not reported.
• Main results:
  • Among the 406 subjects, perfect left-right symmetry was rejected for five of nine ILO pleural disease categories and for both composite scores. In each of these the excess of disease was on the left side.
  • Extent of localized pleural thickening was about twice as likely to be greater on the left as on the right. The ratio of left-worse to right-worse was 1.96 (169 discordant pairs, p less than 0.001).
  • Diaphragmatic calcification was about 2.5 times as likely to be more severe on the left as on the right. The ratio was 2.48 (181 discordant pairs, p less than 0.001).
  • Three measures were about 1.5 times as likely to be more severe on the left: width of localized pleural thickening (ratio 1.46, p 0.01), extent of enface pleural disease (ratio 1.45, p 0.02) and chest wall calcification (ratio 1.63, p 0.01).
  • No category of pleural disease showed a suggestion of excess disease on the right side.
  • Composite pleural disease scores (method of Lilis and coworkers) were worse on the left more often than on the right. One composite had 1.37 times as many cases with worse disease on the left (p 0.03).
  • The other composite score had 1.58 times as many cases with worse disease on the left as on the right (302 discordant pairs, p less than 0.001).
  • Diaphragmatic calcification was most asymmetric in the 75 current smokers: nearly five times more likely to be more severe on the left (ratio 4.80, p less than 0.001). In the 238 former smokers the ratio was 2.87 (p less than 0.001).
  • Among the 92 never smokers, diaphragmatic calcification was nearly symmetric (ratio 1.12, p 0.74).
  • Splitting subjects by presence or absence of parenchymal asbestosis did not show an appreciable difference in the pattern of pleural disease symmetry.
  • Asymmetry in one measure tended to go with asymmetry in another. The strongest association was between enface pleural thickening and chest wall calcification (Kendall's tau B = 0.42).
• The authors' conclusion: The authors concluded that their findings strongly support a left-sided predominance of asbestos-related pleural abnormalities in exposed workers. They found some abnormalities, particularly diaphragmatic calcification, especially apparent on the left in cigarette smokers. They stated that the mechanisms are as yet undefined and need further research.
• Limitations the authors state:
  • The study assumed that plain chest X-rays are equally sensitive for left-sided and right-sided disease. The authors could not test this assumption with their data.
  • The current smoker and never smoker subgroups were too small for most variables to reach statistical significance. Sample sizes within the smoking strata limited the authors' ability to draw inferences.
  • The subgroup with parenchymal asbestosis (71 subjects, 18%) was small.

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: Asbestos-Related Pleural Disease, Pleural Thickening.

Related studies

• Absence of left-sided predominance in asbestos-related pleural plaques: a CT study — J.C. Gallego (1998)
• Roentgenographic evidence for predominant left-sided location of unilateral pleural plaques — B.F. Withers, A.M. Ducatman, et al. (1989)
• Lung crackle characteristics in patients with asbestosis, asbestos-related pleural disease and left ventricular failure using a time-expanded waveform analysis--a comparative study — N. al Jarad, S.W. Davies, et al. (1994)
• Asbestos-related diseases in construction carpenters — M. García-Closas, D.C. Christiani (1995)
• Intensity-modulated radiation therapy with simultaneous integrated boost in unresected left-sided pleural mesothelioma: a case report — S. Cilla, C. Digesú, et al. (2010)
• Asbestos-related pleural disease and asbestosis: a comparison of CT and chest radiography — A.C. Friedman, S.B. Fiel, et al. (1988)

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