Mesothelioma in occupational cohort studies: methodological considerations

Our plain-English summary of Mesothelioma in occupational cohort studies: methodological considerations, by N.C. Wojcik, A.R. Schnatter, W.W. Huebner (Journal of Occupational and Environmental Medicine, 2014).

The study

• Authors: N.C. Wojcik, A.R. Schnatter, W.W. Huebner
• Journal: Journal of Occupational and Environmental Medicine
• Published: 2014;56(1):47-51
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: This article describes effective strategies for the identification and valid assessment of mortality due to mesothelioma.

Methods: We manually reviewed all death certificates for mention of mesothelioma for all International Classification of Diseases (ICD) revisions. We tested the accuracy of our ascertainment method by comparing New Jersey death certificate data from our health status registry with histologically confirmed cases from the New Jersey State Cancer Registry.

Results: We found reasonably good agreement between death certificate diagnoses and histologically confirmed cases, κ coefficient 0.86 (95% confidence interval, 0.76 to 0.95). Most mesothelioma deaths in our test and North American cohorts were coded to unspecified anatomical sites.

Conclusions: Limiting ascertainment to pleura and peritoneum ICD codes underestimates mesothelioma deaths. Reviewing all ICD codes that could contain mesothelioma is the only effective method for complete capture of mesothelioma diagnoses.

In plain English

This methodological article, sponsored by ExxonMobil and written by current and former company employees, described how the company identifies mesothelioma deaths in its worker mortality studies, and tested that method. Before the Tenth Revision of the International Classification of Diseases (ICD), mesothelioma had no specific cause-of-death code. So a nosologist trained by the National Center for Health Statistics manually reviewed every death certificate for any mention of mesothelioma. To test the method, the authors used 3834 male company decedents with New Jersey death certificates from 1979 through 2000. Of these, 28 had been flagged as mesothelioma. The New Jersey State Cancer Registry histologically confirmed 24 of those 28. Four other decedents had registry-confirmed malignant mesothelioma that was not on their death certificates. The authors described agreement as reasonably good, with a kappa coefficient of 0.86 (95% confidence interval 0.76 to 0.95). Most flagged deaths were coded to an unspecified site or to lung. Only 13% were coded to pleura and 4% to peritoneum. The authors concluded that limiting searches to pleura and peritoneum codes underestimates mesothelioma deaths. They noted they could not fully investigate non-matching cases.

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: Methodological study: description of a death certificate review method, tested by record linkage of company death certificate data with a state cancer registry
• Who was studied: 3834 male decedents from a petroleum company's US health status registry (more than 330,000 employee records searched) who had New Jersey death certificates dated 1979 through 2000. The article also reports ICD coding for 88 mesothelioma deaths in the company's North American cohorts (US 1979–2000; Canada 1964–1994).
• Exposure: No asbestos exposure was measured. The study concerned how mesothelioma deaths are identified among company employees, including members of earlier company cohorts and more recent employees from all US business segments.
• Main results:
  • Of the 3834 decedents in the test cohort, 28 had been flagged as mesothelioma by the company's death certificate review.
  • 24 of the 28 company-identified mesothelioma deaths were histologically confirmed as mesothelioma by the New Jersey State Cancer Registry.
  • Four other test cohort decedents had no mesothelioma diagnosis on their death certificates but had microscopic confirmation of malignant mesothelioma in the registry.
  • Agreement between company death certificate ascertainment and the registry: kappa coefficient 0.86 (95% confidence interval, 0.76 to 0.95), described by the authors as reasonably good.
  • Among the 28 company-identified mesothelioma deaths, most were coded to ICD 199.1 (other, unspecified site; 39%) and ICD 162.9 (bronchus and lung, unspecified; 25%).
  • In the New Jersey test, only 13% of mesothelioma deaths were coded to ICD 163 (pleura) and 4% to ICD 158 (peritoneum).
  • In the company's North American cohorts, 88 mesothelioma deaths were captured. Of the 77 coded under ICD-9, 60% were coded to 199.1 (site not specified).
  • In the North American cohorts, 22% of the ICD-9-coded mesothelioma deaths were coded to ICD 163 (pleura) and none to ICD 158 (peritoneum).
  • Most of the 24 matched cases were classified as pleural by the registry.
• The authors' conclusion: The authors concluded that limiting ascertainment to pleura and peritoneum ICD codes underestimates mesothelioma deaths, and that reviewing all ICD codes that could contain mesothelioma is the only effective method for complete capture.
• Limitations the authors state:
  • The authors could not fully research the non-matching cases, partly because all identifiers were removed after merging.
  • Cancer registration covered a shorter period than mortality ascertainment, so earlier mesothelioma death diagnoses could not be confirmed or refuted.
  • Neither database could be treated as the criterion standard, and the precise degree of under-ascertainment could not be determined.
  • The sample was too small to describe the distribution of ICD codes and anatomical sites in detail.

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Death Certificate, Cancer Registry, confidence interval, Pleura, Peritoneum.

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