Area-Level Rurality and Documented Musculoskeletal Symptom Presentation at Rheumatoid Arthritis Diagnosis Among Older Adults in Rural Japan: A Cross-Sectional Study

Background: Recognizing rheumatoid arthritis (RA) in older adults is challenging because clinical presentations are heterogeneous and musculoskeletal symptoms may be attributed to aging or other conditions. Rural context may influence symptom recognition, healthcare-seeking, and diagnostic pathways. We examined whether area-level rurality was associated with musculoskeletal symptoms documented at RA diagnosis among older adults in rural Japan. Methods: We conducted a cross-sectional analysis of 221 patients aged ≥65 years diagnosed with RA at a rural community hospital in Japan between 2016 and 2021. Area-level rurality was measured using the Rurality Index for Japan (RIJ). The primary outcome was documentation of hand, wrist, foot, or ankle symptoms at diagnosis. Logistic regression was used to examine the association between RIJ and the primary outcome. The primary adjusted model included age, sex, and Charlson Comorbidity Index. Results: Among 221 patients, 106 (48.0%) had documented hand, wrist, foot, or ankle symptoms. RIJ scores were higher among patients with these documented symptoms than among those without them (70.0 vs. 64.8; p = 0.004), and the interval from symptom onset to the study-hospital consultation was longer (48.5 vs. 28.0 days; p < 0.001). Each 10-point increase in RIJ was associated with higher odds of documented hand, wrist, foot, or ankle symptoms in the primary adjusted model (OR 1.30, 95% CI 1.07–1.57; p = 0.008). Exploratory sequential models incorporating consultation timing, CRP, and anti-CCP antibody levels yielded similar estimates. Sensitivity analysis accounting for clustering by residential postal-code area did not materially alter the association. Conclusions: Greater area-level rurality was modestly associated with the joint symptom pattern documented at RA diagnosis among older adults in this rural healthcare system. The findings should be interpreted as reflecting differences in documented clinical presentation within a diagnostic pathway rather than as evidence of a distinct rural RA phenotype. In rural settings, clinicians should systematically assess musculoskeletal symptoms in older adults with suspected inflammatory arthritis while remaining attentive to atypical presentations. Prospective multicenter studies using standardized joint assessments and direct individual-level measures of healthcare accessibility are needed to clarify how rural context relates to symptom recognition, healthcare-seeking, referral, and RA diagnosis.