Comment on "pleural plaques and lung function in the Marysville worker cohort: a re-analysis" by Zu et al. (2016)

Our plain-English summary of Comment on "pleural plaques and lung function in the Marysville worker cohort: a re-analysis" by Zu et al. (2016), by J.E. Lockey, K. Dunning, T.J. Hilbert, et al (Inhalation Toxicology, 2017).

The study

• Authors: J.E. Lockey, K. Dunning, T.J. Hilbert, E. Borton, L. Levin, C.H. Rice, R.T. McKay, R. Shipley, C.A. Meyer, C. Perme, G.K. LeMasters
• Journal: Inhalation Toxicology
• Published: 2017;29(2):43-45
• Type of article: Letter, Comment
• Read it: PubMed · Publisher

In plain English

This is a letter to the editor, not a new study. The authors had earlier published analyses of Marysville, Ohio workers exposed from 1957 to 1980 to Libby amphibole asbestos in contaminated vermiculite. They responded to a re-analysis of their data by Zu et al. (2016). The letter notes Zu et al. stated their work was funded by W.R. Grace. The authors argued that Zu et al. cut the lung function group from 154 to 141 workers and moved workers between categories without justification. They also said adding cumulative fiber exposure to the model served to lessen the effect of localized pleural thickening on lung function. The authors noted that Zu et al. still found an apparently unadjusted 5.1% decrement in predicted forced vital capacity (FVC) linked to localized pleural thickening. They called this essentially the same as their own 6.1% decrease in FVC associated with localized pleural thickening only, adjusted for body mass index and smoking. The authors concluded that the Zu et al. paper contained misleading statements, lacked transparency and contained errors, such as saying the cohort included miners.

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 responding to another group's re-analysis (Zu et al., 2016) of the authors' previously published data; no new data were collected
• Who was studied: The Marysville, Ohio worker cohort exposed to Libby amphibole asbestos. The authors' spirometry analyses included 154 workers; the Zu et al. re-analysis used 141.
• Exposure: Libby amphibole asbestos (LAA) in asbestos-contaminated vermiculite from the mine operated by W.R. Grace, to which the Marysville cohort was exposed from 1957 to 1980
• Main results:
  • The letter states that Zu et al. (2016) declared their work was funded by W.R. Grace.
  • The authors' spirometry analyses included 154 workers. The Zu et al. analysis reduced this to 141, excluding 10 of the 13 removed workers because spirometry was done more than 3 years before the HRCT/CT scans.
  • The authors stated that their earlier sensitivity analysis (Lockey et al., 2015b) found similar results after removing 8 of these workers.
  • The authors said Zu et al. moved some workers from the normal and localized pleural thickening (LPT) only categories into an "other" category without justification.
  • The authors said Zu et al. still found an apparently unadjusted 5.1% decrement in predicted forced vital capacity (FVC) related to LPT. They called this essentially the same as the 6.1 they had derived after adjustment for body mass index and pack-years of smoking (Lockey et al., 2015a).
  • The authors stated that in their own analyses (Lockey et al., 2015a,b), the 6.1% decrease in FVC associated with LPT only was statistically significant, as were the RV and TLC findings.
  • The authors stated that adding cumulative fiber exposure (CFE) to the Zu et al. model served to lessen the impact of LPT on lung function.
  • Citing their earlier studies, the authors reported that pleural changes on chest X-ray in this cohort rose from 2.0% in 1980 to 28.7% in 2004 (Rohs et al., 2008). In 2010–2011, the figure was 42.5% using HRCT/CT or, where HRCT/CT was not available, chest radiograph, and 52.9% on HRCT/CT alone (Lockey et al., 2015a).
  • Citing Lockey et al. (2015a), the authors reported that in the full cohort, odds ratios for pleural changes by exposure category were 5.0, 6.8, 10.4 and 9.9. Among those hired on or after 1972, the odds ratios rose from 4.1 to 4.4 and 10.2.
  • The authors said Zu et al. wrongly listed miners in the cohort and twice referred to the workers as men, although women were included.
• The authors' conclusion: The authors concluded that the Zu et al. (2016) paper contained misleading statements, lacked transparency, re-classified workers without justification, used questionable statistical methods, and contained errors.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Pleural Plaques.

Related studies

• Pleural plaques and lung function in the Marysville worker cohort: a re-analysis — K. Zu, G. Tao, et al. (2016)
• Comment on "A systematic review of the association between pleural plaques and changes in lung function" by Kopylev et al (2014) — J.E. Goodman, L.E. Kerper, et al. (2015)
• Reduced lung function in smokers in a lung cancer screening cohort with asbestos exposure and pleural plaques — S. Lopatin, J.C. Tsay, et al. (2016)
• HRCT/CT and associated spirometric effects of low Libby amphibole asbestos exposure — J.E. Lockey, K. Dunning, et al. (2015)
• Risk and significance of chest radiograph and pulmonary function abnormalities in an elderly cohort of former nuclear weapons workers — M.A. Mikulski, P.G. Hartley, et al. (2011)
• A systematic review of the association between pleural plaques and changes in lung function — L. Kopylev, K.Y. Christensen, et al. (2015)

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