A survey of pleural thickening: its relation to asbestos exposure and previous pleural disease

Our plain-English summary of A survey of pleural thickening: its relation to asbestos exposure and previous pleural disease (Environmental Research, 1972).

The study

• Journal: Environmental Research
• Published: 1972;5(2):142-51
• Cited by: 7 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. 001351).

In plain English

This survey compared Birmingham (UK) chest clinic patients aged 40 and over whose X-rays showed pleural thickening or calcification with age- and sex-matched patients whose X-rays did not. Chest physicians reviewed 3863 films of new patients. An expert panel accepted 275 as abnormal, and 186 remained after films showing only unilateral obliteration of the costophrenic angle were excluded. Calcification appeared in 0.7% of all films. Assessors who did not know which patients were cases rated work histories for asbestos exposure. Pairs in which only one member had an exposure history split almost evenly between cases and controls (for one assessor, 19 versus 15, P = 0.61). Among the cases and controls whose histories each assessor team could classify, 4.4% (by one team) and 11.5% (by the other) had definite asbestos exposure. Among 113 interviewed pairs, 43 (38%) of cases and 12 (11%) of controls had past pleural disease or injury rated highly or moderately likely to leave a shadow. The authors concluded there was no strong association between pleural shadowing and asbestos exposure in these clinics. They added that areas with known asbestos exposure might give different results.

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: Matched case-control survey: chest clinic patients with pleural abnormalities on X-ray compared with age- and sex-matched patients with normal films, using interview histories assessed blind
• Who was studied: New patients aged 40 and over at 18 of the 24 chest clinics in the Birmingham Regional Hospital Board area (UK), in a consecutive series going back from June 1966. Of 3863 films examined, 186 cases were kept, each with a matched control. Of the 186 cases, 133 were interviewed (37 had died and 16 were untraceable), and 113 case-control pairs were interviewed.
• Exposure: Occupational and other asbestos exposure, taken from interview histories (an occupational checklist, a list of all jobs, and local dusty materials) and classified by two teams of assessors as definite, possible, none, or insufficient evidence. Previous pleural disease and chest injury were also assessed.
• Main results:
  • Of 387 films picked out by the chest physicians, the expert panel accepted 275 (71%) as showing pleural abnormality.
  • Of the 186 cases, 27 (14.5%) showed pleural calcification, all in the costal pleura.
  • Calcification was present in 0.7% of all 3863 films: 0.9% in males and 0.5% in females.
  • Of the 186 case-control pairs, 63 were unclassifiable for exposure by both teams. Ten more were unclassifiable only by PDO and JCW, and 19 more only by HJD. Ninety-four pairs were classified by both teams. The article does not state how many pairs each team classified on its own. Worked out from these counts, PDO and JCW classified 113 pairs (186 minus 63 minus 10) and HJD classified 104 pairs (186 minus 63 minus 19). The case counts in the article's exposure listing add to the same totals: 6, 21 and 86 for PDO and JCW; 14, 18 and 72 for HJD.
  • In matched pairs where only one member had a positive asbestos exposure history, the split between positive case and positive control was 19 versus 15 (P = 0.61) by assessor HJD, 22 versus 18 (P = 0.43) by assessors PDO and JCW, and 10 versus 7 (P = 0.63) for pairs agreed by both teams. The authors called the imbalance negligible.
  • Among the cases and controls whose histories each team could classify, with or without pleural shadowing, a definite history of asbestos exposure was found in 4.4% according to PDO and JCW and in 11.5% according to HJD. For a possible or definite history, the article gives 22.1% and 25.8%.
  • Of the 113 interviewed pairs, 43 (38%) of the cases with pleural abnormality had a history of pleural disease with a high or moderate likelihood of leaving a shadow.
  • In the controls, 12 (11%) had such a history.
  • After removing all pairs with any likelihood of a medical cause, the PDO and JCW classification gave 8 pairs with a positive case against 1 pair with a positive control (P = 0.04). No such disproportion appeared with HJD's classification or in the pairs agreed by both teams. The authors said the statistical significance must be discounted.
• The authors' conclusion: The authors concluded that there appeared to be no strong association between pleural shadowing and asbestos exposure in chest clinic cases from the areas selected.
• Limitations the authors state:
  • The chest physicians may have interpreted the selection criteria differently, which may explain much of the variation between clinics.
  • Many pairs could not be classified for asbestos exposure because of a lack of adequate information.
  • The two teams of assessors disagreed often. Histories were frequently too vague, and it is not clear which team was right.
  • Judging whether past illness explained the pleural changes may be fallible, so some pairs may have been wrongly eliminated or retained.
  • Studies in areas with known asbestos exposure, such as East London and Leeds, might give different results.

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 Thickening, Asbestos Exposure.

Related studies

• Relationship of mortality, occupation, and pulmonary diffusing capacity to pleural thickening in the First National Health and Nutrition Examination Survey — D.P. Loomis, G.W. Collman, et al. (1989)
• Occupational lung disease survey of respiratory physicians in Northern Ireland — T.F. McKeagney, K. Addley, et al. (2015)
• US prevalence of occupational pleural thickening. A look at chest X-rays from the first National Health and Nutrition Examination Survey — W.J. Rogan, B.C. Gladen, et al. (1987)
• Re: "US prevalence of occupational pleural thickening: a look at chest x-rays from the first National Health and Nutrition Examination Survey" — W.C. Cooper (1989)
• Bilateral pleural thickening: a manifestation of asbestos dust exposure — E.N. Sargent, J. Gordonson, et al. (1978)
• Asbestosis, pleural plaques and diffuse pleural thickening: three distinct benign responses to asbestos exposure — P.A. Gevenois, V. de Maertelaer, et al. (1998)

Browse more research in Environmental Research, or return to medical research.