Response to Baur et al. (2017)

Our plain-English summary of Response to Baur et al. (2017), by C. Schikowsky, M.K. Felten, C. Eisenhawer, et al (American Journal of Industrial Medicine, 2018).

The study

• Authors: C. Schikowsky, M.K. Felten, C. Eisenhawer, M. Das, T. Kraus
• Journal: American Journal of Industrial Medicine
• Published: 2018;61(4):355-357
• Type of article: Letter, Comment
• Read it: PubMed · Publisher

In plain English

This is a letter to the editor, not a new study. In it the authors replied to a commentary by Baur and colleagues on the authors' 2017 study of lung function in asbestos-exposed workers whose CT scans were normal. The authors argued that a meta-analysis by Wilken et al and a study by Lopatin et al did not contradict their results. They described where their study group came from. More than 20,000 employees of a German energy supplier were contacted, and 1199 received at least one multiple detector-CT scan. The group had a mean exposure duration of 21.4 years and a mean cumulative exposure of 49 fibre-years. Exposure was estimated with standardized software rather than from monitoring of each worker's own workplace. The authors restated that the link between the measure "Rtot" and cumulative exposure had a P-value of 0.09, which they rated as not statistically significant. They acknowledged possible selection bias and a likely healthy worker effect. The authors concluded that their results clearly suggested no effect of asbestos on lung function without structural change visible on CT. However, they said they could not rule out such an effect in some asbestos victims.

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: the authors' reply to a commentary (Baur et al.) on their own earlier study, Schikowsky et al. 2017, Am J Ind Med 60:422-431
• Who was studied: From a health surveillance program of a German energy supplier. More than 20,000 former and still-active employees who had probably been exposed to asbestos were contacted. 8565 confirmed occupational exposure. 7,703 (printed as "7.703") were examined at least once. 1199 received at least one multiple detector-CT (MDCT) scan, 859 of them at the Institute of Occupational and Social Medicine (IOSM), Aachen. Ages ranged from 36 to 80 years.
• Exposure: Occupational asbestos exposure; the fiber type is not specified. The mean exposure duration was 21.4 years and the mean cumulative exposure was 49 fibre-years. Individual cumulative exposure in fiber-years was estimated with standardized software that used workplace monitoring data from various companies and industries.
• Main results:
  • In the original study group, the univariate regression of "Rtot" on cumulative asbestos exposure (fiber-years) gave a P-value of 0.09. The authors rated this as statistically non-significant, and multivariate analysis gave a similar non-significant result.
  • A post hoc power analysis (univariate linear regression) gave a power of 0.65 for a small effect and 0.99 for a moderate effect.
  • The authors referred to a weak correlation between time since end of exposure and DLCO/VA. They suggested it might be explained by age-related changes and by inadequate age adjustment of the DLCO/VA reference values.
• The authors' conclusion: The authors concluded that neither the Wilken et al meta-analysis nor the Lopatin et al study contradicted their results. They said they could not rule out that, in some asbestos victims, lung function may be affected without structural change visible on CT. Even so, they considered it necessary to report results that they said clearly suggested no such effects.
• Limitations the authors state:
  • The authors could not rule out some selection (response) bias during recruitment.
  • No actual monitoring data from the participants' own workplaces were available, so exposure was estimated.
  • The cohort was a sample of surviving formerly exposed workers who volunteered. The authors did not claim it was representative of German power industry workers.
  • The authors considered it reasonable to assume that the healthy worker effect had some influence on their results.

Related studies

• Digital tomosynthesis of the chest: current and emerging applications — S.H. Chou, G.A. Kicska, et al. (2014)
• Lung function not affected by asbestos exposure in workers with normal Computed Tomography scan — C. Schikowsky, M.K. Felten, et al. (2017)
• Non-response bias in a surveillance program for asbestos-related lung cancer — L. Knoll, M.K. Felten, et al. (2011)
• Is it useful to combine sputum cytology and low-dose spiral computed tomography for early detection of lung cancer in formerly asbestos-exposed power industry workers? — M.K. Felten, L. Knoll, et al. (2014)
• Radiological surveillance of formerly asbestos-exposed power industry workers: rates and risk factors of benign changes on chest X-ray and MDCT — C. Eisenhawer, M.K. Felten, et al. (2014)
• Commentary to the article lung function not affected by asbestos exposure in workers with normal Computed Tomography scan, by Schikowsky, Felten, et al., 2017 — X. Baur, B. Terracini, et al. (2018)

Browse more research in American Journal of Industrial Medicine, or return to medical research.