Rheumatoid arthritis (RA) has been associated with lower socioeconomic status (SES), but the reasons for this are not known.
To examine childhood SES measures, SES trajectory and other perinatal factors in relation to RA.
The sample included 50 884 women, aged 35-74 (84% non-Hispanic white) enrolled 2004-9 in a US national cohort study. In baseline questionnaires, cases (N=424, 0.8%) reported RA diagnosis after age 16, ever use of disease-modifying antirheumatic drugs or steroids for RA and ≥6 weeks bilateral joint swelling. Childhood SES measures are presented as OR and 95% CI adjusted for age and race/ethnicity. Analyses of perinatal factors also adjusted for childhood SES, and joint effects of childhood and adult SES and smoking exposures were evaluated.
Patients with RA reported lower childhood household education (<12 years vs college degree; OR=1.7; 95% CI 1.1 to 2.5), food insecurity (OR=1.5, 95% CI 1.1 to 2.0) and young maternal age (<20 vs 20-34 years; OR=1.7, 95% CI 1.2 to 2.5), with a trend (p<0.0001) for increasing number of adverse factors (OR=3.0; 95% CI 1.3 to 7.0; 4 vs 0 factors) compared with non-cases. Low birth weight (<2500 g) [corrected] and preconception paternal smoking were independently associated with RA. Together, lower childhood SES and adult education (<college degree) were associated with RA (interaction p=0.03), with a joint effect magnitude similar to a history of paternal and adult smoking.
RA was associated with low childhood SES sustained into adulthood, with cumulative effects across multiple measures, suggesting the importance of other unmeasured factors linking SES and RA.