Comparison of expert and job-exposure matrix-based retrospective exposure assessment of occupational carcinogens in The Netherlands Cohort Study

Our plain-English summary of Comparison of expert and job-exposure matrix-based retrospective exposure assessment of occupational carcinogens in The Netherlands Cohort Study, by N.S. Offermans, R. Vermeulen, A. Burdorf, et al (Occupational and Environmental Medicine, 2012).

The study

• Authors: N.S. Offermans, R. Vermeulen, A. Burdorf, S. Peters, R.A. Goldbohm, T. Koeman, M. van Tongeren, T. Kauppinen, I. Kant, H. Kromhout, P.A. van den Brandt
• Journal: Occupational and Environmental Medicine
• Published: 2012;69(10):745-51
• Cited by: 45 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: Reliable retrospective exposure assessment continues to be a challenge in most population-based studies. Several methodologies exist for estimating exposures retrospectively, of which case-by-case expert assessment and job-exposure matrices (JEMs) are commonly used. This study evaluated the reliability of exposure estimates for selected carcinogens obtained through three JEMs by comparing the estimates with case-by-case expert assessment within the Netherlands Cohort Study (NLCS).

Methods: The NLCS includes 58,279 men aged 55-69 years at enrolment in 1986. For a subcohort of these men (n=1630), expert assessment is available for exposure to asbestos, polycyclic aromatic hydrocarbons (PAHs) and welding fumes. Reliability of the different JEMs (DOMJEM (asbestos, PAHs), FINJEM (asbestos, PAHs and welding fumes) and Asbestos JEM (asbestos) was determined by assessing the agreement between these JEMs and the expert assessment.

Results: Expert assessment revealed the lowest prevalence of exposure for all three exposures (asbestos 9.3%; PAHs 5.3%; welding fumes 11.7%). The DOMJEM showed the highest level of agreement with the expert assessment for asbestos and PAHs (κs=0.29 and 0.42, respectively), closely followed by the FINJEM. For welding fumes, concordance between the expert assessment and FINJEM was high (κ=0.70). The Asbestos JEM showed poor agreement with the expert asbestos assessment (κ=0.10).

Conclusions: This study shows case-by-case expert assessment to result in the lowest prevalence of occupational exposure in the NLCS. Furthermore, the DOMJEM and FINJEM proved to be rather similar in agreement when compared with the expert assessment. The Asbestos JEM appeared to be less appropriate for use in the NLCS.

In plain English

Within the Netherlands Cohort Study, the authors compared ways of estimating past workplace exposure to asbestos, polycyclic aromatic hydrocarbons (PAHs) and welding fumes. For 1455 men from a random subcohort of 1630 with usable job histories, an earlier case-by-case assessment by two experts was compared with three job-exposure matrices (JEMs), which give everyone in a job the same estimate: Dutch DOMJEM and Asbestos JEM and Finnish FINJEM. The experts classed the fewest men as exposed: 9.3% for asbestos, against 28.3% to 32.9% with the JEMs. Weighted kappa agreement with the experts on asbestos was poor for all three JEMs: DOMJEM 0.29 (95% CI 0.23 to 0.32), FINJEM 0.23 (0.19 to 0.29), Asbestos JEM 0.10 (0.05 to 0.13). It was moderate for PAHs and high for welding fumes (FINJEM 0.70, 95% CI 0.66 to 0.74, or 0.65 to 0.74 in the table). The authors concluded DOMJEM and FINJEM performed rather similarly and the Asbestos JEM appeared less appropriate for this cohort. They noted that no data existed on agreement between the two experts, and that low exposure prevalence makes kappa imprecise.

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: Methods-comparison (reliability) study within a subcohort of a prospective population-based cohort. It compared three job-exposure matrices with an existing case-by-case expert assessment, which served as the reference.
• Who was studied: Male members of the random subcohort (1630 men) of the Netherlands Cohort Study, which enrolled 58,279 men aged 55 to 69 in 1986. Of these, 1455 men had job histories complete enough to assign job codes. Their mean age was 61.3 years, and their working lives spanned 1929 to 1986.
• Exposure: Occupational exposure to asbestos (fibre type not specified), PAHs and welding fumes. Cumulative exposure was estimated from self-reported lifetime job histories up to 1986, using expert assessment, the DOMJEM (asbestos, PAHs), the FINJEM (asbestos, PAHs, welding fumes) and the Asbestos JEM (asbestos).
• Main results:
  • Prevalence of asbestos exposure among the 1455 men: 9.3% by expert assessment, 28.3% by FINJEM, 30.0% by DOMJEM and 32.9% by the Asbestos JEM.
  • Prevalence of PAH exposure: 5.3% by expert assessment, 8.5% by DOMJEM and 10.1% by FINJEM.
  • Prevalence of welding fume exposure: 11.7% by expert assessment and 15.6% by FINJEM.
  • Agreement with the expert assessment for asbestos (weighted Cohen's kappa): DOMJEM 0.29 (95% CI 0.23 to 0.32) and FINJEM 0.23 (95% CI 0.19 to 0.29).
  • Agreement between the expert assessment and the Asbestos JEM for asbestos was low: kappa 0.10 (95% CI 0.05 to 0.13).
  • For asbestos, DOMJEM and FINJEM agreed with each other most closely: kappa 0.50 (95% CI 0.47 to 0.55).
  • For PAHs, DOMJEM showed the highest agreement with the expert assessment: kappa 0.42 (95% CI 0.29 to 0.52).
  • For welding fumes, agreement between the expert assessment and FINJEM was high: kappa 0.70. The text gives a 95% CI of 0.66 to 0.74, and Table 2 gives 0.65 to 0.74.
  • In the authors' summary, compared with the expert assessment, the JEMs showed poor agreement for asbestos (all JEMs), moderate agreement for PAHs (DOMJEM and FINJEM) and high agreement for welding fumes (FINJEM).
  • A sensitivity analysis was restricted to the 135 men the experts judged exposed to asbestos. In it, FINJEM (kappa 0.09) and the Asbestos JEM (kappa 0.04) showed hardly any agreement with the expert assessment.
• The authors' conclusion: The authors concluded that case-by-case expert assessment gave the lowest prevalence of occupational exposure in the NLCS, that the DOMJEM and FINJEM were rather similar in agreement with the expert assessment, and that the Asbestos JEM appeared less appropriate for use in the NLCS.
• Limitations the authors state:
  • No data were available on agreement between the two experts, so the reliability of the expert assessment itself could not be judged.
  • Exposure prevalence was low in this population-based study, which makes Cohen's kappa estimates imprecise.
  • Only limited information was available to the experts, which may have hampered their assessment of exposure patterns.
  • The relation of either method to true exposure is unknown, so the amount of exposure misclassification for each method could not be quantified.

Topics

Medical terms in this study, explained in our Lexicon: Cohort Study, Occupational Exposure.

Related studies

• Occupational exposure to carcinogens and risk of lung cancer: results from The Netherlands cohort study — A.J. van Loon, I.J. Kant, et al. (1997)
• Linking expert judgement and trends in occupational exposure into a job-exposure matrix for historical exposure to asbestos in the Netherlands — P. Swuste, M. Dahhan, et al. (2008)
• Development of an exposure measurement database on five lung carcinogens (ExpoSYN) for quantitative retrospective occupational exposure assessment — S. Peters, R. Vermeulen, et al. (2012)
• Occupational asbestos exposure and risk of pleural mesothelioma, lung cancer, and laryngeal cancer in the prospective Netherlands cohort study — N.S. Offermans, R. Vermeulen, et al. (2014)
• Occupational asbestos exposure and risk of esophageal, gastric and colorectal cancer in the prospective Netherlands Cohort Study — N.S. Offermans, R. Vermeulen, et al. (2014)
• Socioeconomic status and lung cancer incidence in men in The Netherlands: is there a role for occupational exposure? — A.J. van Loon, R.A. Goldbohm, et al. (1997)

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