Occupational history questionnaire for job coding and exposure assessment in systemic autoimmune rheumatic diseases

Objectives: Systemic autoimmune rheumatic diseases (SARDs) develop in genetically susceptible individuals when exposed to environmental factors such as respirable crystalline silica (RCS) particles. Assessing occupational exposure in population-based studies is critical but resource intensive, often requiring expert interviews. This study aimed to develop and validate a self-administered occupational history questionnaire that allows for International Standard Classification of Occupations 1968 (ISCO-68) coding and exposure assessment as a cost-effective alternative to traditional interviews. Methods: Seventy RA patients participated by completing a standardized telephone interview and the newly developed self-administered questionnaire. Participants were also asked to recruit two gender- and age-matched family members for comparison. Independent observers assigned ISCO-68 codes to the reported jobs and a job exposure matrix was used to link each job to RCS exposure. Agreement between the interview and questionnaire was assessed by comparing reported working years, ISCO-68 job codes and RCS exposure. Cohen’s κ and intraclass correlation were calculated to evaluate agreement and interobserver variability. Results: The patient response rate was 77%, but family member controls had a low response rate (6.45%), likely impacted by the COVID-19 pandemic. Agreement for reported working years was 91%, with a Cohen’s κ of 0.87 for ever/never RCS exposure. Manual ISCO coding introduced variability, but interobserver reliability remained high (intraclass correlation coefficient = 0.91). Conclusion: The self-administered occupational history questionnaire provides a valid, cost-effective and time-efficient alternative to telephone interviews for assessing occupational history and estimating RCS exposure in epidemiological research. Future studies should explore automated coding systems and improved strategies for control recruitment.