The 6-joint ultrasonographic assessment: a valid, sensitive-to-change and feasible method for evaluating joint inflammation in RA

Objective. Musculoskeletal US can be useful in monitoring RA. It can be time-consuming and there is no consensus in defining the joints to evaluate. We assessed the validity, sensitivity to change and feasibility of a reduced 6-joint US score in patients with RA starting therapy with an anti-TNF agent. Methods. A group of consecutive RA patients starting etanercept were investigated. The patients underwent clinical evaluation, laboratory tests and US assessment at baseline and 3 months. A semi-quantitative score (0-3) was used to evaluate synovial effusion (SE), synovial proliferation (SP) and power Doppler (PD) signal in 12 joints. A process of data reduction, based on the frequency of synovial site involvement by US-SE, US-SP and US-PD signal, was conducted to investigate the validity of a 6-joint US assessment. Results. Forty-five RA patients were evaluated. A significant decrease in all clinical, serological and 12-joint US parameters was found at follow-up. A significant correlation between changes in the DAS-28 and changes in the US scores in the 12-joint assessment was observed at follow-up (P < 0.001). A reduced 6-joint US score was obtained, including wrist, second MCP and knee joints of both sides, detecting US-SE in 97.78% of patients, US-SP in 100% of patients and positive US-PD in 100% of patients. The 6-joint US score showed a highly significant correlation with changes in DAS-28 (P < 0.001). The 6-joint evaluation was quick and easy to do. Conclusion. A 6-joint US assessment may be a valid, sensitive-to-change and feasible method for evaluating joint inflammation in RA.