Socioeconomic disparities in self-reported arthritis and arthritis subtype prevalence among U.S. adults

Arthritis is a leading cause of pain, functional limitation, and disability among U.S. adults, yet nationally representative evidence on long-term socioeconomic gradients in subtype-specific arthritis prevalence remains limited. We examined temporal trends in the prevalence of self-reported arthritis and major arthritis subtypes according to educational attainment and poverty income ratio (PIR) using NHANES 1999–2023. We conducted a repeated cross-sectional analysis of 66,314 adults aged ≥ 20 years with known self-reported arthritis status from NHANES 1999–2023. Arthritis was defined by self-report of ever having been told by a doctor or health professional that the participant had arthritis. Subtypes included rheumatoid arthritis (RA), osteoarthritis (OA), other arthritis, unspecified arthritis, and psoriatic arthritis (PsA); PsA was available from 2009 to 2010 onward. Educational attainment and PIR were analyzed as socioeconomic status (SES) indicators. Survey weights, strata, and primary sampling units were incorporated. Weighted prevalence and 95% confidence intervals (CIs) were estimated, and age-adjusted prevalence was emphasized in the main analyses. Temporal trends were evaluated across NHANES cycles and ordered SES categories. Multiple imputation for missing educational attainment and PIR was performed as a sensitivity analysis. In pooled analyses across NHANES 1999–2023, age-adjusted overall arthritis prevalence was 25.8% (95% CI, 24.9%-26.7%) among adults with below high school education and 20.0% (95% CI, 19.3%-20.8%) among college graduates (P for trend <0.001). By income, age-adjusted overall arthritis prevalence was 27.8% (95% CI, 27.0%-28.7%) in the PIR < 1.30 group, 24.5% (95% CI, 23.8%-25.2%) in the 1.30 ≤ PIR < 3.50 group, and 21.7% (95% CI, 21.0%-22.4%) in the PIR ≥ 3.50 group (P for trend <0.001). Across NHANES cycles, age-adjusted overall arthritis prevalence increased modestly from 21.7% (95% CI, 20.2%-23.2%) in 1999–2000 to 24.3% (95% CI, 23.2%-25.4%) in 2021–2023 (P for trend =0.033). OA prevalence increased substantially over time (6.1% to 12.1%; P for trend <0.001), whereas RA remained comparatively stable (5.6% to 4.1%; P for trend =0.246). Unspecified arthritis declined from 9.4% to 4.7% (P for trend <0.001). Across pooled SES strata, RA and unspecified arthritis prevalence tended to be higher in lower-SES groups, whereas OA prevalence was higher in more socioeconomically advantaged groups. Arthritis burden in U.S. adults differed across socioeconomic status, with lower educational attainment and lower PIR associated with higher overall arthritis prevalence. Subtype-specific patterns were heterogeneous. These findings underscore the need for targeted public health and clinical strategies to reduce socioeconomic disparities in arthritis detection, diagnosis, and management.