Association between socioeconomic status and comorbidities among patients with rheumatoid arthritis: results of a nationwide cross-sectional survey

OBJECTIVES: We examined the association between socioeconomic status (SES) and comorbidity distribution among patients with RA. METHODS: Information on comprehensive health status of 1088 RA patients (weighted n = 612 303) was obtained from the 2007-2015 Korea National Health and Nutrition Examination Survey database. SES components were household equivalence income, education and area of residence. To minimize confounding by age, patients were stratified by median age (63 years). Age-adjusted odds ratio (OR) with 95% confidence interval (95% CI) was estimated, comparing weighted prevalence of individual comorbidities between low and high SES groups in each age stratum. RESULTS: Among RA patients aged <63 years (mean 49 years, 70% female), we observed age-adjusted associations of depression (OR 2.13, 95% CI 1.01, 4.53), depressive mood (OR 2.68, 95% CI 1.54, 4.65), suicide ideation (OR 3.01, 95% CI 1.79, 5.07), diabetes (OR 3.09, 95%CI 1.31, 7.29), obesity (OR 2.04, 95% CI 1.30, 3.20), hypertriglyceridemia (OR 2.36, 95% CI 1.28, 4.34) and osteoarthritis (OR 2.12, 95% CI 1.13, 3.99) with low income, of suicide ideation with low education (OR 2.25, 95% CI 1.14, 4.44), but no association of any comorbidities with area of residence. Unhealthy behavior patterns were comparable between low- and high-income groups but patients with low income reported a numerically higher rate of failed access to necessary healthcare services. We did not find any association between SES and comorbidities among those aged ⩾63 years (mean 72 years, 83% female). CONCLUSION: Among Korean RA patients aged <63 years, socioeconomic inequalities of multiple comorbidities in mental, cardiometabolic and musculoskeletal systems were found.