Association of Socioeconomic Status and Health Lifestyles with Incident Early-onset and Late-onset Rheumatoid Arthritis: A Prospective Cohort Study in the UK

Abstract

Socioeconomic status (SES) and lifestyle behaviors are recognized determinants of chronic disease risk, but their relative contributions to early-onset and late-onset rheumatoid arthritis (RA) remain uncertain. This cohort study comprised 35,360 participants from the UK Biobank. SES was derived from education, income, and employment using latent class analysis, and lifestyle was assessed through a four-component score (smoking, alcohol, physical activity, and diet). Incident RA was identified through hospital and mortality records. Cox models estimated hazard ratios (HRs) for early-onset (<65 years) and late-onset (≥65 years) RA, with subgroup and sensitivity analyses performed to test robustness. During follow-up, 997 incident RA cases were identified (318 early-onset, 679 late-onset). Lower SES was strongly associated with a higher risk of RA in both groups, with a greater relative effect in early-onset disease (low vs. high SES, HR: 2.31, 95% confidence interval [CI]: 1.66–3.22) than in late-onset disease (HR: 1.99, 95% CI: 1.63–2.43). A healthy lifestyle was associated with reduced RA risk, particularly in late-onset RA (HR: 0.62, 95% CI: 0.50–0.75 for lifestyle score 3–4 vs. 0–1), while the effect was more modest in early-onset RA (HR: 0.74, 95% CI: 0.55–0.98). Joint analyses showed the highest risks among individuals with both low SES and poor lifestyle, with HRs of 3.42 (95% CI: 1.93–6.07) for early-onset and 3.24 (95% CI: 2.29–4.60) for late-onset RA. Socioeconomic disadvantage is a predominant driver of early-onset RA, whereas lifestyle factors are more influential for late-onset disease. Healthy lifestyles can attenuate but not fully offset the risk associated with low SES.