Review of the Kilburn and Warshaw Chest article--airways obstruction from asbestos exposure

Our plain-English summary of Review of the Kilburn and Warshaw Chest article--airways obstruction from asbestos exposure, by R.N. Jones, H.W. Glindmeyer, H. Weill (Chest, 1995).

The study

• Authors: R.N. Jones, H.W. Glindmeyer, H. Weill
• Journal: Chest
• Published: 1995;107(6):1727-9
• Type of article: Comment
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

This commentary, part of a debate in print, critiqued a 1994 Chest article by Kilburn and Warshaw, which concluded that "Asbestos exposure causes airway obstruction and asbestosis increases it." The original study compared 8,720 self-selected asbestos-exposed construction and shipyard workers with a reference group drawn from a Michigan population sample. The critics argued that this reference group had been studied in the early 1980s by other investigators for a different purpose and was not comparable in age and smoking history. They noted that a single reader interpreted all chest radiographs knowing each worker's exposure and health status, and gave his reading in the worker's presence. The prediction and smoking-adjustment equations used came from younger, health-screened subjects. The critics said these would underestimate smoking effects in older smokers, whose mean ages were 58 and 63 years. Reanalysing the published group means with the Morris et al equations, the critics found generally normal values in never smokers. Ratios of forced expiratory volume in 1 second (FEV1) to forced vital capacity (FVC) in the asbestos-exposed and asbestosis groups exceeded those of the reference group. The ratio of residual volume to total lung capacity (RV/TLC) in current smokers was 34.1% in nonexposed and 47.9% in exposed men. Expressed as percent predicted, the values were 105.6 and 108.6. The authors concluded that the original paper failed to demonstrate its claimed differences and instead supported the conclusion that asbestos does not cause significant obstruction.

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 "debate in print" commentary in Chest, not a new study. The authors critiqued a 1994 Chest article by Kilburn and Warshaw concluding that asbestos exposure causes airway obstruction and asbestosis increases it. They noted the comparison group came from a Michigan population study run by other investigators for a different purpose. They said the exposed workers were self-selected. They also said one reader interpreted all chest x-rays knowing each worker's exposure and health status. They re-expressed Kilburn and Warshaw's published group averages using other prediction equations (Morris et al). Among never smokers, values were generally normal, and FEV1/FVC as percent predicted was higher in the asbestos-exposed (107.7) and asbestosis (106.8) groups than in the reference group (105.4), though measured ratios were lower (75.6% and 75.2% versus 80.0%). In current smokers, a raw difference in residual volume to total lung capacity of 34.1% versus 47.9% became 105.6 versus 108.6 percent predicted. The authors noted they could not compute a p-value without the full data set. They concluded that the paper actually supports the view that asbestos does not cause significant obstruction.

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: Commentary ("debate in print") critiquing a published study, with a partial re-analysis of that study's published group averages
• Who was studied: No new subjects. The commentary examined Kilburn and Warshaw's published data on 8,720 asbestos-exposed construction and shipyard workers, compared with a reference group from a Michigan population study (Miller et al, 1986)
• Exposure: Asbestos exposure among construction and shipyard workers in the critiqued study, with comparisons between workers with and without x-ray-diagnosed asbestosis; fiber types not stated
• Main results:
  • The authors noted that the reference group in the critiqued study was studied in the early 1980s by different investigators for a different purpose
  • The authors said the exposed study population was self-selected, which biases toward worse health status
  • The authors noted that one reader interpreted the chest x-rays while knowing each worker's exposure and health status
  • Applying the Morris et al equations to never smokers' group averages gave generally normal values. FEV1/FVC expressed as percent predicted was 105.4 in the no-exposure group, 107.7 in the asbestos-exposed group and 106.8 in the asbestosis group. The observed mean ratios were 80.0%, 75.6% and 75.2% respectively
  • In current smokers, raw residual volume to total lung capacity was 34.1% in nonexposed and 47.9% in asbestos-exposed workers (p=0.0001). Expressed as percent predicted, the values were 105.6 and 108.6, a 3% difference
  • Among never smokers, the R2 value of 2.4% indicated that small opacity profusion on x-ray explained virtually none of the variability in FEF25-75
  • Never smokers' mean FEF25-75 values were above 80% predicted in both the asbestos-exposed and the asbestosis groups
  • The authors stated that proper analysis showed Kilburn and Warshaw failed to demonstrate the differences behind their main conclusions
• The authors' conclusion: The authors concluded that the critiqued paper actually supports the opposite conclusion: that asbestos does not cause significant obstruction
• Limitations the authors state:
  • The authors could not compute a p-value for their recalculated comparison without the whole data set
  • The recalculated values are group averages expressed as percent of predicted averages, not averages of individual percent-predicted values

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, Chest X-Ray, FEV1, Total Lung Capacity (TLC).

Related studies

• Airways obstruction from asbestos exposure. Effects of asbestosis and smoking — K.H. Kilburn, R.H. Warshaw (1994)
• Association between increased small airway obstruction and asbestos exposure in patients with asbestosis — X. Yang, Y. Yan, et al. (2018)
• Abnormal lung function associated with asbestos disease of the pleura, the lung, and both: a comparative analysis — K.H. Kilburn, R.H. Warshaw (1991)
• Lung function and chest radiograph abnormalities among construction insulators — S.M. Kennedy, S. Vedal, et al. (1991)
• Does asbestos exposure cause airway obstruction, in the absence of confirmed asbestosis? — J. Ameille, M. Letourneux, et al. (2010)
• Airway obstruction in asbestos-exposed shipyard workers: with and without irregular opacities — K.H. Kilburn, R.H. Warshaw (1990)

Browse more research in Chest, or return to medical research.