Response to Hein and Schubauer-Berigan

Our plain-English summary of Response to Hein and Schubauer-Berigan, by J.Y. Zhou (International Journal of Radiation Biology, 2015).

The study

• Author: J.Y. Zhou
• Journal: International Journal of Radiation Biology
• Published: 2015;91(11):911-2
• Type of article: Letter, Comment
• Read it: PubMed · Publisher

In plain English

This letter to the editor reports no new study data. The author replied to Hein and Schubauer-Berigan, who had criticized the author's 2014 article on bias in the proportionate mortality ratio (PMR), which compares a cause's share of deaths in a group with its share in a reference population. The 2014 article concerned radiation and mesothelioma, but this letter gives no asbestos or mesothelioma data. The author argued that the critics' simulation was unnecessary and inappropriate, and that they miscalculated the average PMR for the author's method. In invented examples with five causes of death, groups with no deaths from some causes had PMRs above 1 for the other causes (1.071, 1.250 and 1.667) with no real excess. The author wrote that this bias is negligible for a large study population over many cause-of-death categories, or when the sample size ratio is large, and that combining categories does not remove it. The author argued that studies such as Gibb et al. 2013 therefore give false positive findings when no real excess exists, and suggested revising LTAS.NET.

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 (reply to a letter by Hein and Schubauer-Berigan), with invented illustrative examples; no new study data
• Who was studied: No real population was studied. The letter uses invented examples: a referent population and five hypothetical study groups, spread over five cause-of-death categories.
• Exposure: No exposure was studied. The letter discusses the statistical method (proportionate mortality ratio) used in analyses of radiation and mesothelioma, including Gibb et al. 2013 on the US Transuranium and Uranium Registries.
• Main results:
  • In the invented examples, cause-of-death categories with zero deaths in a study group inflated the proportions of the remaining categories, and therefore inflated their PMRs.
  • In the invented examples, Studies 3, 4 and 5 had the same numbers of deaths in their non-zero categories as the referent population pattern. Even so, the PMR for cause 4 was 1.071 in Study 3, 1.250 in Study 4 and 1.667 in Study 5. In Studies 1 and 2 it was 1.000.
  • The author stated that the bias from zero-death categories is negligible in practice with a large study population over a large number of cause-of-death categories, or when the sample size ratio is large.
  • The author stated that combining disease categories, as the critics suggested, does not remove the small-sample PMR bias.
  • The author argued that Hein and Schubauer-Berigan calculated the mean PMR for the author's proposed method incorrectly.
• The authors' conclusion: The author concluded that, because the small-sample bias causes overestimation of PMR, studies such as Gibb et al. 2013 produce false positive findings when no real excess of cause-specific deaths is present. The author suggested that LTAS.NET be revised to correct for this bias.

Topics

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

Related studies

• Bias in the proportionate mortality ratio analysis of small study populations: a case on analyses of radiation and mesothelioma — J.Y. Zhou (2014)
• A Monte Carlo t Test to Evaluate Mesothelioma and Radiation in the US Transuranium and Uranium Registries — J.Y. Zhou, S.L. McComish, et al. (2019)
• Risk of cancer from occupational exposure to ionising radiation: retrospective cohort study of workers in France, the United Kingdom, and the United States (INWORKS) — D.B. Richardson, E. Cardis, et al. (2015)
• Malignant mesothelioma following radiation exposure — K.H. Antman, J.M. Corson, et al. (1983)
• Malignant peritoneal mesothelioma following radiotherapy for seminoma of the testis — R.J. Stock, Y.S. Fu, et al. (1979)
• Ionizing radiation: a risk factor for mesothelioma — J.E. Goodman, M.A. Nascarella, et al. (2009)

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