Socioeconomic and occupational risk factors for rheumatoid arthritis: a nationwide study based on hospitalizations in Sweden

OBJECTIVE: To investigate possible associations between socioeconomic status, occupation, and hospitalization for rheumatoid arthritis (RA).

METHODS: A nationwide database was constructed by linking the Swedish Census to the Hospital Discharge Register in order to obtain data on all first hospitalizations for RA in Sweden during the study period 1964 to 2004. Standardized incidence ratios (SIR) and 95% confidence intervals were calculated by socioeconomic status (education level) and occupation for men and women aged 30 years and older. Three cohorts were defined based on occupational titles recorded in Swedish census data in 1960, 1970, and 1980.

RESULTS: A total of 13,820 male and 14,509 female hospitalizations for RA were identified during the study period. Men and women with an education level > 12 years had significantly decreased SIR. Among men, significantly increased SIR were present in all 3 cohorts among farmers, miners and quarry workers, electrical workers, other construction workers, and engine and motor operators. Among women, assistant nurses and religious, juridical, and other social-science-related workers had significantly increased SIR in all 3 cohorts.

CONCLUSION: Socioeconomic status and occupation sometimes carry a significantly increased risk of hospitalization for RA. Future studies could investigate specific agents in the occupations for which increased risks are identified.