Cases of alleged asbestos-related disease: a radiologic re-evaluation

Our plain-English summary of Cases of alleged asbestos-related disease: a radiologic re-evaluation, by R.B. Reger, W.S. Cole, E.N. Sargent, et al (Journal of Occupational Medicine., 1990).

The study

• Authors: R.B. Reger, W.S. Cole, E.N. Sargent, P.S. Wheeler
• Journal: Journal of Occupational Medicine.
• Published: 1990;32(11):1088-90
• Cited by: 6 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. 003681).

Abstract

Chest radiographs were re-evaluated from 439 active and retired tireworkers previously designated as having a condition consistent with an asbestiform mineral exposure. The review was performed in an independent manner by three board-certified radiologists according to guidelines from an international classification system. The percentage of cases with abnormalities consistent with an asbestiform mineral exposure found separately by the three radiologists was 3.7, 3.0, and 2.7%. Application of an algorithm to form a consensus evaluation indicated that approximately 3.6% (16) of the subjects evaluated may have a condition consistent with an asbestos exposure. A more detailed review, however, revealed that only 11 workers, or 2.5% of the total, would have a reasonable likelihood of having such a condition. Most cases were normal and the majority of abnormalities present on the radiographs evaluated were nonoccupational in origin. Prevalent conditions identified included healed tuberculosis, histoplasmosis, emphysema, discoid atelectasis, effusions, healed rib fractures, scarring due to infection or old inflammatory disease, possible cancer, miscellaneous nonspecific linear markings consistent with cigarette smoking and aging, and heart and vascular system diseases--the latter evidenced by an abnormally large number of subjects with healed coronary artery bypass surgery and pacemaker implants. In summary, the best estimate from this study indicates that possibly 16 (3.6%), but more realistically 11 (2.5%), of the 439 tireworkers evaluated may have a condition consistent with exposure to an asbestiform mineral. This represents a 40-fold difference between the re-evaluation results and the original survey work.

In plain English

This study re-read chest X-rays of 439 active and retired tire workers from one site. A 1986 screening of about 700 to 750 workers had identified them as having conditions consistent with asbestiform mineral exposure, and they had filed legal claims for asbestos-related injury. Their average age was 60.3. Three board-certified radiologists, not told the study's purpose, read the films independently using the 1980 International Labour Office classification. Reading separately, the radiologists found abnormalities consistent with asbestiform mineral exposure in 3.7, 3.0 and 2.7% of the workers. By consensus, 16 of the 439 (3.6%) had conditions that may be consistent with asbestos exposure. Five of these cases did not meet the exact consensus rules, so the authors judged that only 11 (2.5%) had a high likelihood. Most workers (265, 60.4%) had normal films, and 158 (36.0%) showed conditions of nonoccupational origin, such as healed tuberculosis, emphysema, and heart and vascular disease. The authors concluded that the originally reported prevalence was mistakenly high; their estimate was 40-fold lower. They noted that workers originally judged negative were not re-examined.

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: Radiologic re-evaluation (independent re-reading by three radiologists) of chest films from a prior screening
• Who was studied: 439 active and retired tireworkers at one site, drawn from 700 to 750 tireworkers screened in 1986, who had been designated as having a condition consistent with asbestiform mineral exposure and had filed legal claims; average age 60.3, more than 90% of those with a recorded age were 50 or older
• Exposure: Exposure to asbestiform minerals. The original diagnoses rested on chest films together with a history of at least potential exposure to asbestos and/or talc. No specific fiber types are named.
• Main results:
  • Reading separately, the three radiologists found likely asbestos-related conditions in 3.7, 3.0 and 2.7% of the 439 workers. These groups overlapped, so the percentages are not additive.
  • By consensus, 16 (3.6%) of the 439 workers had conditions that may be consistent with asbestos exposure: 7 (1.6%) with parenchymal abnormalities at a median profusion above 0/1, 8 (1.8%) with pleural abnormalities on which two of three radiologists agreed, and 1 (0.2%) with both.
  • At least five of the 16 consensus cases were questioned because they did not meet the exact consensus rules. Without them, 11 (2.5%) of the 439 workers had a high likelihood of a condition consistent with asbestiform mineral exposure.
  • 265 (60.4%) of the 439 workers had normal films and 158 (36.0%) had conditions of nonoccupational origin. These included healed tuberculosis, histoplasmosis, emphysema, discoid atelectasis, effusions, healed rib fractures, scarring, possible cancer, nonspecific markings consistent with smoking and aging, and heart and vascular system diseases.
  • The re-evaluation estimate of possible asbestos-related disease was 40-fold lower than the original survey results.
  • Most films were of good or acceptable quality, but one radiologist considered 35 films (8%) unreadable.
• The authors' conclusion: The authors concluded that the prevalence of disease originally noted was mistakenly high. In their view, the prevalence of asbestos-related or other occupational conditions in the sample re-evaluated was not of epidemic proportions, and widespread alarm was unwarranted.
• Limitations the authors state:
  • Workers originally considered negative for asbestos-related disease were not included, because of administrative necessities and time constraints.
  • In the original screening, the chest radiograph was only one of the diagnostic aids used to classify workers.
  • Even the 2.5% figure may be overstated. Many workers were classified as category 1/0, which represents minimal changes that could result from smoking, aging, poor inspiration, or conditions that mimic asbestosis.

Topics

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

Medical terms in this study, explained in our Lexicon: Chest X-Ray, Asbestiform, Asbestos Exposure, Emphysema, Atelectasis.

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