American College of Chest Physicians consensus statement on the respiratory health effects of asbestos. Results of a Delphi study

Our plain-English summary of American College of Chest Physicians consensus statement on the respiratory health effects of asbestos. Results of a Delphi study, by D.E. Banks, R. Shi, J. McLarty, et al (Chest, 2009).

The study

• Authors: D.E. Banks, R. Shi, J. McLarty, C.T. Cowl, D. Smith, S.M. Tarlo, F. Daroowalla, J. Balmes, M. Baumann
• Journal: Chest
• Published: 2009;135(6):1619-1627
• Type of article: Consensus statement
• Cited by: 41 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: The diagnosis of and criteria for the evaluation of asbestos-related disease impairment remains controversial after decades of research. Assessing agreement among experts who study pneumoconiosis, and diagnose and treat patients with asbestos-related respiratory conditions may be the first step in clarifying clinical and forensic/administrative issues associated with asbestos-related pulmonary conditions.

Methods: We conducted a Delphi study, an iterative method of obtaining consensus among a group of experts. An expert panel was identified using an objective, nonbiased algorithm, based on the number of asbestos-related disease publications authored during the preceding 10-year period. Identified experts were invited to participate by accessing an Internet site. Each expert was presented statements developed by the authors regarding the diagnosis or treatment of asbestos-related disease; experts then ranked their degree of agreement or disagreement utilizing an 11-level modified Likert scale for each statement. Each expert was asked to justify their selection and to suggest references in support of their opinion. The Wilcoxon signed rank test and the interquartile range were used to define "consensus." The results of the collective Likert rankings, deidentified comments, and suggested references as well as the initial consensus results were then provided to the participating experts. Each panel member then ranked their extent of agreement with a modified statement for which consensus was not achieved. The process was repeated three times.

Results: Consensus was achieved on all but 9 of 32 statements.

Conclusions: Consensus was not achieved for nine statements. These statements may be topics for future research.

In plain English

This was a Delphi study, in which experts rated statements over repeated rounds and saw the group's answers between rounds. The authors found experts through a PubMed search of asbestos publications from 1991 to 2002 and invited 71. In the three rounds, 34, 29 and 24 experts voted. Experts scored 32 statements from 0 (strong disagreement) to 10 (strong agreement), and consensus was defined statistically. The panel reached consensus on 23 statements, agreeing with 17 and disagreeing with 6. It agreed that asbestos exposure can cause pleural plaques, and that workers with significant exposure but no asbestosis are at increased risk of bronchogenic carcinoma. It disagreed that pleural plaques alter lung function to a clinically significant degree. It also disagreed that workers with asbestos-induced pleural abnormalities face higher lung cancer risk than similarly exposed workers without them. No consensus was reached on nine statements. These included whether a heavy exposure sufficient to cause asbestosis, together with sufficient latency, is necessary to attribute lung cancer to asbestos. The authors concluded that these unresolved questions indicate areas for future research.

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: Delphi consensus study: an expert panel rated statements over three internet-based rounds, with consensus defined statistically using the Wilcoxon signed rank test and the interquartile range
• Who was studied: International experts identified from a PubMed search (January 1, 1991 to May 15, 2002) of clinically relevant asbestos publications, which yielded 1,106 references. The 95 first authors with 3 or more publications formed the pool; one was deceased, leaving 94 eligible. The 71 with known e-mail addresses were invited. 34 experts voted in round 1, 29 in round 2 and 24 in round 3.
• Exposure: Asbestos exposure in general; the article names no specific fiber type. The panel rated 32 statements on the diagnosis, attribution and health effects of asbestos-related respiratory disease, on a scale from 0 (strong disagreement) to 10 (strong agreement), with 5 meaning no opinion.
• Main results:
  • Of the 32 statements, the panel reached some degree of consensus on 23: agreement on 17 and disagreement on 6. No consensus was reached on 9.
  • Consensus was reached on 7 of 25 questions in round 1, on 12 of the remaining 25 in round 2, and on 4 of the remaining 13 in round 3.
  • The panel agreed that asbestos exposure can cause pleural plaques and can cause diffuse pleural thickening.
  • The panel agreed that workers with significant asbestos exposure who do not have asbestosis are at increased risk of bronchogenic carcinoma.
  • The panel disagreed that pleural plaques alter lung function to a clinically significant degree.
  • The panel disagreed that workers with asbestos-induced pleural abnormalities are at increased lung cancer risk compared with workers with similar exposures but without these abnormalities. The authors described this as strong disagreement.
  • The panel disagreed that chest radiographs are a sensitive method to diagnose interstitial disease attributable to asbestos exposure. After three rounds, the median score was 2, the IQR 3 and the p value 0.001.
  • No consensus was reached on the statement that a heavy asbestos exposure (sufficient to cause asbestosis) with sufficient latency is necessary to establish asbestos exposure as causative for lung cancer.
  • Other statements without consensus included:
• whether a reasonable scheme can apportion smoking and asbestos exposure in a smoking worker with lung cancer;
• whether CT scanning should be used to screen populations at risk;
• whether nonsmoking workers with significant exposure (without asbestosis) have at least double the risk of bronchogenic carcinoma compared with nonsmoking workers with low-level exposure;
• whether smoking workers with significant exposure (without asbestosis) have at least double the risk compared with nonexposed smokers.
  • On whether a decline in small airway flow rates in a nonsmoker can be attributed to asbestos exposure, experts seemed evenly divided (p = 0.76), and results did not change substantially between rounds.
• The authors' conclusion: The authors concluded that the Delphi method gave a systematic approach to disputed issues in asbestos-related disease, and that the questions still unresolved indicate areas for future research.
• Limitations the authors state:
  • Potential for nonresponse bias.
  • A different pool of experts might have judged the issues differently.
  • Face-to-face discussion might have produced different results.
  • More rounds might have produced consensus on all statements, but this was impractical.
  • Experts without an e-mail address, or whose address could not be found, were excluded. The authors were not certain whether this affected the outcome.

Topics

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

Medical terms in this study, explained in our Lexicon: Pneumoconiosis.

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