Ultrasonographic evaluation of joint involvement in early rheumatoid arthritis in clinical remission : power Doppler signal predicts short-term relapse

OBJECTIVES: This study aimed to evaluate the usefulness of a systematic musculoskeletal ultrasonographic (US) assessment in the detection of residual disease activity in patients with early RA who achieved clinical remission. METHODS: We prospectively studied 106 early RA patients receiving conventional DMARDs according to a disease activity score (DAS)-steered therapeutic protocol over a 24-month period. Standard evaluation included clinical, laboratory, functional and systematic (44 joints) US assessment. US indexes of grey scale (GS) and power Doppler (PD) synovitis were correlated with clinical evaluation, laboratory indexes and clinical outcome. Clinical remission was defined when DAS was <1.6 at two consecutive visits 3 months apart. RESULTS: US examination was significantly more sensitive than clinical examination, both in active disease and in remission. In patients with an active disease, both clinical and US indexes correlated with CRP, whereas in remission only PD still remained significantly correlated. In clinical remission, 95% of the patients showed residual GS synovitis, and 41% of them showed a positive PD signal. Positive PD signal, even in a single joint, resulted the main predictor of relapse within 6 months, both in univariable and multivariable logistic regression analysis. CONCLUSIONS: In a cohort of early RA patients treated with conventional DMARDs, US-GS can detect residual disease activity more sensitively than clinical examination both in active disease and in remission. Moreover, PD-positive synovial hypertrophy identifies an ongoing inflammation even during remission and predicts short-term relapse.