Failure to prove asbestos exposure produces obstructive lung disease

Our plain-English summary of Failure to prove asbestos exposure produces obstructive lung disease, by D.D. Smith (Chest, 2004).

The study

• Author: D.D. Smith
• Journal: Chest
• Published: 2004;126(3):1000
• Type of article: Comment, Letter
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

In this letter to the editor, Smith commented on a study by Ohar and colleagues (Chest, February 2004). That study had analyzed relationships among asbestos exposure, cigarette smoking, lung function and chest radiograph abnormalities in 3,383 patients referred mainly by plaintiff attorneys and trade union members. He noted that the study had reported clinically significant airflow obstruction as well as restrictive changes, attributed to a synergistic effect of smoking and asbestos exposure.

He pointed to what he described as contradictions. First, 73% of patients with mixed restrictive/obstructive findings had a normal total lung capacity, yet the authors later stated that 83% of smokers and 71% of nonsmokers with obstruction and a reduced FVC had hyperinflation. Second, a figure gave a value of 5,381 (16.0%), although 16% of 3,312 is 530.

He questioned the statistical method used to compare FEV1/FVC ratios in nonsmokers with high versus low ILO scores (72.8% vs 76.2%), citing Rothman and Greenland. He also raised these points:

• Diffusing capacity results were not presented.
• The cause of restriction (diffuse pleural disease vs asbestosis) was not given.
• Total lung capacity should have been used for clinical correlations.
• ILO scoring is prone to error.
• Patients referred largely by plaintiff attorneys may exaggerate asbestos exposure and minimize smoking.
• The bibliography was selective.

He concluded that the article failed to prove that asbestos exposure produces obstructive lung disease.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This is a letter to the editor, not a research study. The author, from the University of Washington, criticized a 2004 Chest article by Ohar and colleagues. That article examined asbestos exposure, cigarette smoking, lung function and chest X-ray findings in 3,383 patients referred mainly by plaintiff attorneys and trade union members. The author argued that the article's figures were inconsistent. It reported that 73% of patients with mixed restrictive and obstructive findings had normal total lung capacity, but later said that 83% of smokers and 71% of nonsmokers with obstruction and reduced FVC had hyperinflation. The author also said a count in its Figure 2 was wrong. The author questioned the statistical method used to compare nonsmokers with high and low ILO X-ray scores. Other criticisms were that diffusion measurements were missing, the cause of restriction was not given, patients seeking compensation might misreport smoking and asbestos exposure, and the bibliography was selective. The author concluded the article failed to prove that asbestos exposure produces obstructive lung disease.

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: Letter to the editor commenting on another published study (Ohar et al., Chest 2004); no new data
• Who was studied: No population of its own. The letter discusses the Ohar et al. study of 3,383 patients referred primarily by plaintiff attorneys and trade union members.
• Exposure: Asbestos exposure and cigarette smoking, as studied in the Ohar et al. article. No fiber types are named.
• Main results:
  • The author pointed to an apparent contradiction in the Ohar et al. article. It reported that 73% of patients with mixed restrictive/obstructive findings had normal total lung capacity and only 27% had coexistent restriction. Later it stated that 83% of smokers and 71% of nonsmokers with obstruction and a reduced FVC had hyperinflation.
  • The author stated that the value 5,381 (16.0%) in the article's Figure 2 was incorrect, because 16% of 3,312 is 530.
  • Among nonsmokers, the article reported an FEV1/FVC ratio of 72.8% for patients with high ILO scores and 76.2% for those with low ILO scores, with a p value of 0.025 using a Bonferroni correction. The author cited Rothman and Greenland as calling this method imprecise and said it was not clear the difference was truly statistically significant.
  • The author criticized the absence of diffusing capacity measurements, which might have identified emphysema. The author also noted that no information was given on the cause of restrictive disease (diffuse pleural disease vs asbestosis).
  • The author argued that patients referred largely by plaintiff attorneys tend to exaggerate asbestos exposure and minimize smoking history. The author also noted that ILO scoring is prone to error.
  • The author stated that the article's bibliography was selective and did not cite articles disagreeing with its conclusions.
• The authors' conclusion: The author concluded that the Ohar et al. article raised more questions than it answered and failed to prove its authors' hypothesis that asbestos exposure produces obstructive lung disease.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Obstructive Lung Disease, Chest X-Ray, Plaintiff, Synergistic Effect, Total Lung Capacity (TLC), FEV1/FVC Ratio, Diffusing Capacity (DLCO).

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• Incident chronic obstructive pulmonary disease associated with occupation, industry, and workplace exposures in the Health and Retirement Study — S.R. Silver, W.A. Alarcon, et al. (2021)
• A somatic TSHR mutation in a patient with lung adenocarcinoma with bronchioloalveolar carcinoma, coronary artery disease and severe chronic obstructive pulmonary disease — J.W. Kim, S. Lee, et al. (2012)
• Changing patterns in asbestos-induced lung disease — P. De Vuyst, P.A. Gevenois, et al. (2004)
• Total lung capacity. An insensitive measure of impairment in patients with asbestosis and chronic obstructive pulmonary disease? — S. Barnhart, L.D. Hudson, et al. (1988)
• Infectious disease risk in asbestos abatement workers — J.H. Lange, G. Mastrangelo, et al. (2012)

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