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

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.

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.

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).

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.