Joint Tenderness, Not Patient-Reported Pain, Predicts Ultrasound Inflammation in Anti-CCP Positive RA Risk

Early and accurate diagnosis of rheumatoid arthritis (RA) is crucial for preventing irreversible joint damage and improving long-term outcomes. Individuals positive for anti-cyclic citrullinated peptide (anti-CCP) antibodies, even without overt clinical arthritis, are at high risk of developing RA. Current diagnostic approaches often rely on patient-reported symptoms like joint pain, which can be subjective and inconsistent with objective inflammation. There's a critical need to identify more reliable clinical indicators that correlate with subclinical inflammatory changes detectable by imaging, guiding earlier intervention and potentially refining screening protocols for this high-risk population.

This cross-sectional study analyzed 323 participants from a Leeds (UK) cohort of anti-CCP positive individuals presenting with new musculoskeletal complaints but no clinical arthritis. Assessments included a comprehensive physical examination for joint tenderness, and a mannequin diagram where participants marked painful joints to capture patient-reported joint pain (PRJP). Ultrasound scans were performed on wrists, metacarpo-phalangeal joints 1-5 (MCPs1-5), proximal interphalangeal joints 1-5 (PIPs1-5), elbows, knees, ankles, metatarso-phalangeal joints 1-5 (MTPs1-5), finger flexor tendons (2-5), and extensor carpi ulnaris. Grey scale (GS), power Doppler (PD), tenosynovitis, and erosions were evaluated. A generalised estimating equations model was used to assess associations between tenderness/PRJP and ultrasound findings at the joint-level, adjusting for age and sex.

Joint tenderness demonstrated a significant association with ultrasound abnormalities, predominantly Power Doppler (PD) signals, across multiple joints including wrists, MCPs, PIPs, elbows, knees, and MTPs (all p≤0.05). Grey scale (GS) changes and erosions were also associated with tenderness, though to a lesser extent. In contrast, the association between patient-reported joint pain (PRJP) and ultrasound abnormalities was notably more inconsistent, primarily observed for GS changes in the feet (all p≤0.05).