LAUSR

OBJECTIVES Differentiation between polymyalgia rheumatica (PMR) and elderly onset rheumatoid arthritis (EORA), especially in elderly patients, is often difficult due to similarities in symptoms and serological kinetics. In this study, we aimed to analyze the predictors of EORA with PMR-like onset. METHODS Seventy-two patients diagnosed with PMR, who attended our hospital for routine care and underwent musculoskeletal ultrasonography (MSUS) at that time were evaluated. Synovitis was evaluated semi-quantitatively (0-3) by gray scale (GS) and power doppler (PD) in 24 joints (both hands [wrist, metacarpophalageal, and proximal interphalangeal joints] and both shoulder joints). RESULTS Overall, 18 patients had RA (25.0%); the mean age was 75.0 years, and 34.7% and 65.3% were male and female, respectively. In PMR and PMR/EORA groups, multivariate logistic analysis showed that rheumatoid factor (RF) positivity, GS ≥2 of hand joints, and PD ≥1 of hand joints were independent factors with significant differences. At least 1 of the 3 factors had a sensitivity of 88.9% and specificity of 92.6%. CONCLUSIONS Presence of at least one of the criteria: RF positivity, GS ≥ 2, and PD ≥ 1 of hand joints, suggested the possibility of developing EORA within 1 year of PMR diagnosis.