Objectives Retrospective exposure assessment remains a problematic aspect of population-based case–control studies. Different methods have been developed, including case-by-case expert assessment and job–exposure matrices (JEM). The present analyses compare exposure prevalence and risk estimates derived by different exposure assessment methods.
Methods In the context of a case–control study conducted in seven European countries, exposure was estimated for asbestos, diesel motor emissions (DME) and crystalline silica, using three different assessment methods. First, experts assigned exposures to all reported jobs on a case-by-case basis. Second, a population-specific JEM (PSJEM) was developed using the expert assessments of controls only, and re-applied to all study subjects. Third, an independent general population JEM (GPJEM) was created by occupational exposure experts not involved in the original study, and applied to study subjects. Results from these methods were compared.
Results There was poor to fair agreement in assigned exposure between expert assessment and the GPJEM (kappas: asbestos 0.17; DME 0.48; silica 0.38). Exposure prevalence was significantly heterogeneous (p<0.01) between countries for all three agents and assessment methods. For asbestos and DME, significant country heterogeneity in risk estimates was observed when using expert assessment. When applying the GPJEM, the heterogeneity in risk estimates for asbestos and, to some extent, silica diminished.
Conclusions It has been previously advocated that the expert assessment approach to assign exposures based on detailed questionnaire responses provides more accurate exposure estimates than JEM-based results. However, current results demonstrated little, if any, advantage of case-by-case assessment when compared to a JEM approach.
- Exposure misclassification
- multi-centre study
- exposure assessment
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This manuscript was written on behalf of the INCO group (the principal investigators of the original studies): David Zaridze, Neonila Szeszenia-Dabrowska, Peter Rudnai, Jolanta Lissowska, Eleonora Fabianova, Dana Mates, Vladimir Bencko, Lenka Foretova, Vladimir Janout, Joelle Fevotte, Tony Fletcher and Paul Brennan.
Current analyses were performed within the scope of the SYNERGY project. SYNERGY is a pooled analysis of case–control studies on the joint effects of occupational carcinogens in the development of lung cancer, which started in 2007. This project is coordinated by the International Agency for Research on Cancer (IARC).
Funding This study is funded by the German Social Accident Insurance (DGUV).
Competing interests None.
Provenance and peer review Not commissioned; externally peer reviewed.
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