Background: Systemic autoimmune rheumatic diseases develop in individuals with a susceptible genetic background upon exposure to environmental triggers, including occupational exposure to respirable crystalline silica particles (RCS). In general population-based studies, job history taking is an important step in assigning exposure.

Objectives: We aimed to create and validate a self-administered occupational history questionnaire that allows for International Standard Classification of Occupation (ISCO)-68 job coding and exposure assessment, reducing time-investment and expenses in epidemiological research.

Methods: Patients with rheumatoid arthritis (N=70) were asked to participate in a standardised telephone interview and to complete an expert-developed, self-administered occupational history questionnaire, designed for this study. Participants were asked to contact two gender- and age-matched family member controls. Two independent observers assigned ISCO-68 codes to the reported jobs. A job exposure matrix linked each job to RCS exposure. Response rate to the questionnaire, observed percentage of agreement of reported working years and consensus of ISCO-68 job codes were estimated between the questionnaire and interview. We calculated Cohen’s κ for binary ever/never RCS exposure (comparing interview to questionnaire) and for interobserver variability of ISCO codes (based on the questionnaire), and intraclass correlation for cumulative RCS exposure.

Results: The response rate of patients and family members was 77% and 6.45%, respectively. Agreement was 91% for reported working years, 71% for ISCO-68 coding and Cohen’s κ for ever/never RCS exposure was strong (0.87) when the telephone interview was compared to the questionnaire. Intraclass correlation for cumulative RCS exposure between 2 observers was excellent (0.91).

Conclusion: Our questionnaire is a valid, cost- and time-saving alternative to a telephone interview to assess occupational history and consequently estimate exposure via a job-exposure matrix.

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Acknowledgements: NIL.

Disclosure of Interests: None declared.