Differential peeky bias

Our plain-English summary of Differential peeky bias, by D.S. Egilman, M.A. Billings (International Journal of Occupational and Environmental Health, 2006).

The study

• Authors: D.S. Egilman, M.A. Billings
• Journal: International Journal of Occupational and Environmental Health
• Published: 2006;12(3):294
• Type of article: Letter
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

In this letter to the editor, the authors responded to issues raised by legal counsel for automobile manufacturers about their 2005 paper, "Abuse of Epidemiology: Automobile Manufacturers Manufacture a Defense to Asbestos Liability." First, they clarified that the figure they had quoted from McDonald et al., 0.4 mesothelioma cases per 1,000 in chrysotile asbestos factories, was deaths per 1,000 deaths. At Chrysler counsel's suggestion, they compared it with United States data for 1979, the earliest year available, which showed 0.18 mesothelioma deaths per 1,000 deaths. They stated that this was less than half the McDonald rate and supported their earlier conclusion that the McDonald rate was more than double the expected rate. Second, they noted that McDonald and McDonald gave two conflicting descriptions of the exposure period studied: up to 10 years before death, and 10 or more years before death. They argued that either way the data included a ten-year period in which few mesotheliomas would be expected, which would have diluted any effect. Third, they corrected their description of the scoring scale in the Goodman et al. meta-analysis. They reported that the highest-scoring study was Teschke's (5 of 8), not Hessel et al.'s (4). They stated that Goodman et al. sought extra exposure information from some but not all study authors and used it to exclude two studies unfavorable to their sponsors. One example was Malker et al., which reported the highest relative risk for mechanics (2.4). The authors named this error "differential peeky bias."

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 item is a letter to the editor, not a research study. The authors answered issues raised by legal counsel for automobile manufacturers about their earlier paper, "Abuse of Epidemiology: Automobile Manufacturers Manufacture a Defense to Asbestos Liability." First, they clarified that a figure they had quoted from McDonald et al., 0.4 mesothelioma cases per 1,000 in chrysotile asbestos factories, was actually deaths per 1,000 deaths. United States data for 1979 showed 0.18 mesothelioma deaths per 1,000 deaths, less than half that rate, which the authors said further supported their conclusion that the McDonald rate was more than double the expected rate. Second, they noted that the McDonald and McDonald study described its exposure time window in two conflicting ways. They argued that either way, the exposure data used would have diluted any potential effect. Third, they corrected how they had described the scoring scale in a meta-analysis by Goodman et al. Finally, they argued that Goodman et al. sought extra exposure information from the authors of some studies but not others. In their account, this led Goodman et al. to exclude a study by Malker et al. that reported a relative risk of 2.4 for mechanics. The authors named this error "differential peeky bias."

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 criticisms of the authors' earlier paper; no new study was conducted
• Who was studied: No study population. The letter discusses published studies (McDonald et al.; McDonald and McDonald; the Goodman et al. meta-analysis) and cites United States mesothelioma death data for 1979
• Exposure: Occupational asbestos exposure: chrysotile asbestos factory work (McDonald et al. figure) and brake work among motor vehicle mechanics (Goodman et al. meta-analysis)
• Main results:
  • The McDonald et al. figure of 0.4 mesothelioma cases per 1,000 individuals in chrysotile asbestos factories was deaths per 1,000 deaths
  • The United States rate for 1979 (0.18 mesothelioma deaths per 1,000 deaths) was less than half the 0.4 per 1,000 deaths reported by McDonald et al.
  • The McDonald and McDonald study gave two conflicting explanations of its exposure time window. The authors argued that, in either case, the exposure data used would have diluted any potential effect
  • Correction: Goodman et al. used what appears to be a 13-point scale based on 11 criteria, not an 11-point scale. The maximum score appears to be 8, not 9
  • Correction: the highest-ranking study in the Goodman et al. meta-analysis scored 5 out of 8 and was the Teschke paper. The Hessel et al. paper scored 4, the second highest
  • The authors stated that Goodman et al. excluded the Malker et al. paper, which reported the highest relative risk (RR, 2.4) for mechanics, because one of its authors could not document actual brake work
• The authors' conclusion: The authors named the selective pursuit of unreported exposure information to enhance favorable data or discredit unfavorable data "differential peeky bias," and said Goodman et al. used it to exclude two studies unfavorable to their sponsors' financial interests

Topics

Medical terms in this study, explained in our Lexicon: Epidemiology, Mesothelioma, Chrysotile, Meta-Analysis, Relative Risk.

Related studies

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• Assessing specific causation of mesothelioma following exposure to chrysotile asbestos-containing brake dust — M.D. Freeman, S.S. Kohles (2012)
• Evaluation of Confounding and Selection Bias in Epidemiological Studies of Populations Exposed to Low-Dose, High-Energy Photon Radiation — M.K. Schubauer-Berigan, A. Berrington de Gonzalez, et al. (2020)
• Estimating the effect of cumulative occupational asbestos exposure on time to lung cancer mortality: using structural nested failure-time models to account for healthy-worker survivor bias — A.I. Naimi, S.R. Cole, et al. (2014)
• Assessing the component associations of the healthy worker survivor bias: occupational asbestos exposure and lung cancer mortality — A.I. Naimi, S.R. Cole, et al. (2013)
• Evaluation of selection bias in a cross-sectional survey — I.J. Selikoff, H. Seidman (1991)

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