Retrospective exposure assessment and quality control in an international multi-centre case-control study

Area of Science:

• Occupational health
• Epidemiology
• Genetics

Background:

• International case-control studies require robust exposure assessment.
• Chromosomal aberrations (CA) in lymphocytes may indicate cancer risk.
• Evaluating occupational carcinogen exposure is key to understanding cancer etiology.

Purpose of the Study:

• To present the exposure assessment method and quality control (QC) procedure for an international, multi-centre case-control study.
• To assess if occupational carcinogen exposure influences the predictive value of high chromosomal aberration (CA) frequency for cancer risk.
• To harmonize exposure assessment criteria and QC procedures across Nordic and Italian cohorts.

Main Methods:

• Occupational hygienists assessed exposures in Denmark, Finland, Italy, Norway, and Sweden.
• Exposure status was coded based on original CA studies, not entire work life.
• Reliability was measured using deviation from majority, Cohen's kappa, and agreement proportion.

Main Results:

• Reassessing exposures significantly altered original exposure statuses.
• Harmonization of criteria enhanced assessment conformity.
• Original assessors reported higher exposure prevalence than others, suggesting potential biases.

Conclusions:

• Consistent exposure assessments in international retrospective studies necessitate a well-defined protocol.
• Involving country-specific hygienists is vital due to environmental differences.
• Recommended QC includes described methods and round-table meetings to minimize information bias.