Comparison of exposure assessment methods in a lung cancer case-control study: performance of a lifelong task-based questionnaire for asbestos and PAHs

Our plain-English summary of Comparison of exposure assessment methods in a lung cancer case-control study: performance of a lifelong task-based questionnaire for asbestos and PAHs, by E. Bourgkard, P. Wild, M. Gonzalez, et al (Occupational and Environmental Medicine, 2013).

The study

• Authors: E. Bourgkard, P. Wild, M. Gonzalez, J. Févotte, E. Penven, C. Paris
• Journal: Occupational and Environmental Medicine
• Published: 2013;70(12):884-91
• Cited by: 17 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: To describe the performance of a lifelong task-based questionnaire (TBQ) in estimating exposures compared with other approaches in the context of a case-control study.

Methods: A sample of 93 subjects was randomly selected from a lung cancer case-control study corresponding to 497 jobs. For each job, exposure assessments for asbestos and polycyclic aromatic hydrocarbons (PAHs) were obtained by expertise (TBQ expertise) and by algorithm using the TBQ (TBQ algorithm) as well as by expert appraisals based on all available occupational data (REFERENCE expertise) considered to be the gold standard. Additionally, a Job Exposure Matrix (JEM)-based evaluation for asbestos was also obtained. On the 497 jobs, the various evaluations were contrasted using Cohen's κ coefficient of agreement. Additionally, on the total case-control population, the asbestos dose-response relationship based on the TBQ algorithm was compared with the JEM-based assessment.

Results: Regarding asbestos, the TBQ-exposure estimates agreed well with the REFERENCE estimate (TBQ expertise: level-weighted κ (lwk)=0.68; TBQ algorithm: lwk=0.61) but less so with the JEM estimate (TBQ expertise: lwk=0.31; TBQ algorithm: lwk=0.26). Regarding PAHs, the agreements between REFERENCE expertise and TBQ were less good (TBQ expertise: lwk=0.43; TBQ algorithm: lwk=0.36). In the case-control study analysis, the dose-response relationship between lung cancer and cumulative asbestos based on the JEM is less steep than with the TBQ-algorithm exposure assessment and statistically non-significant.

Conclusions: Asbestos-exposure estimates based on the TBQ were consistent with the REFERENCE expertise and yielded a steeper dose-response relationship than the JEM. For PAHs, results were less clear.

In plain English

In a lung cancer case-control study of men in Lorraine, France, the authors compared ways of estimating workplace exposure to asbestos and polycyclic aromatic hydrocarbons (PAHs). For 93 randomly chosen participants (41 cases, 52 controls; 497 jobs), a short task-based questionnaire (TBQ) was scored by experts and by algorithm. Both were compared with a detailed reference expert assessment and, for asbestos, a job exposure matrix (JEM). For asbestos, weighted agreement (kappa) with the reference was 0.68 for expert scoring and 0.61 for the algorithm, versus 0.31 and 0.26 with the JEM. PAH agreement was 0.43 and 0.36. Among all 246 cases and 531 controls, adjusted for non-occupational factors including smoking, the lung cancer odds ratio per unit of the natural log of (cumulative asbestos fibre-years per mL plus 1) was 1.27 (95% CI 1.15 to 1.40) with the TBQ algorithm and 1.10 (0.98 to 1.24), not significant, with the JEM. Also adjusting for other workplace exposures, these became 1.18 (1.06 to 1.31) and 1.02 (0.91 to 1.16). The authors concluded TBQ asbestos estimates were consistent with the reference; PAH results were less clear.

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: Comparison of occupational exposure assessment methods (validation substudy) within a population-based lung cancer case-control study
• Who was studied: 93 randomly selected subjects (41 lung cancer cases, 52 controls), covering 497 jobs, drawn from a case-control study of men aged 40–80 in the northern Lorraine region of France. The dose-response comparison used the whole case-control study of 246 cases and 531 controls.
• Exposure: Occupational asbestos (fiber type not specified) and PAH exposure. The task-based questionnaire had 15 asbestos tasks and 5 PAH tasks. Asbestos levels were coded as 0 non-exposed, 1 less than 1, 2 from 1 to 10, and 3 at least 10 fibres per mL. In the case-control analysis, cumulative asbestos exposure was expressed as the natural log of (fibre-years per mL plus 1), so that non-exposed subjects had a zero value.
• Main results:
  • Asbestos, TBQ expertise compared with the reference expertise (exposed vs non-exposed): 90.0% agreement, kappa 0.70; specificity 96%, sensitivity 69%.
  • Asbestos, TBQ expertise compared with the reference expertise (exposure levels): 86.4% agreement, weighted kappa 0.68, with no discordance greater than one level.
  • Asbestos, TBQ algorithm compared with the reference expertise: 90.4% agreement, kappa 0.73, specificity 95%, sensitivity 77%; exposure levels 81.7% agreement, weighted kappa 0.61.
  • PAHs, TBQ expertise compared with the reference expertise: 84.5% agreement, kappa 0.47, specificity 94%, sensitivity 48%; levels weighted kappa 0.43.
  • PAHs, TBQ algorithm compared with the reference expertise: 83.2% agreement, kappa 0.40, sensitivity 39%, specificity 95%; levels weighted kappa 0.36.
  • Asbestos, TBQ expertise compared with the JEM: 78.7% of job-periods in the same exposed/non-exposed group (kappa 0.36) and 76.1% at the same level (weighted kappa 0.31). TBQ algorithm compared with the JEM: weighted kappa 0.26 for levels.
  • In the full case-control study (246 cases, 531 controls), in models adjusted only for non-occupational confounders including smoking, the lung cancer odds ratio per unit of ln(cumulative asbestos fibre-years per mL plus 1) was 1.27 (95% CI 1.15 to 1.40) using the TBQ algorithm and 1.10 (95% CI 0.98 to 1.24) using the JEM.
  • After further adjustment for occupational confounders (cumulative PAHs and crystalline silica, ever exposure to diesel motor exhaust), the TBQ-algorithm odds ratio was 1.18 (95% CI 1.06 to 1.31) and remained significant.
  • After the same occupational adjustment, the JEM-based odds ratio was 1.02 (95% CI 0.91 to 1.16).
• The authors' conclusion: The authors concluded that asbestos exposure estimates from the TBQ were consistent with the reference expertise and gave a steeper dose-response relationship than the JEM, while results for PAHs were less clear. They considered the TBQ a promising way to assess exposure to carcinogens in case-control studies.
• Limitations the authors state:
  • Whether expert assessment can be treated as a gold standard is disputed.
  • None of the comparisons can show which assessment is more relevant.
  • Discordances for the reference and the TBQ expert assessments were resolved by the same team of experts, so the two assessments were not fully independent.
  • The TBQ missed some asbestos exposures (for example demolition of ovens, chimneys or asbestos-containing coatings, and some construction maintenance tasks).
  • The five PAH questions missed a substantial part of the exposing tasks.
  • In the limited dataset, agreement was not better among cases than controls, possibly reflecting differential recall bias. Some TBQ questions explicitly mention asbestos.

Topics

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

Medical terms in this study, explained in our Lexicon: Lung Cancer, Case-Control Study, Dose-response relationship.

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