Usefulness of Power Doppler Ultrasound for Prediction of Re‐Therapy With Rituximab in Rheumatoid Arthritis: A Prospective Study of Longstanding Rheumatoid Arthritis Patients

Objective To assess the value of gray‐scale (GS) and power Doppler (PD) ultrasound (US) in detecting inflammatory/destructive changes and for prediction of necessity of re‐therapy with rituximab (RTX) in patients with rheumatoid arthritis (RA) over 1 year of followup. Methods GSUS and PDUS were performed to assess synovitis, tenosynovitis, and erosions on the clinically dominant hand and forefoot of 20 patients with RA before and after therapy with RTX. US parameters were compared with clinical (Disease Activity Score in 28 joints, tender/swollen joint counts, and patients' visual analog scale of disease activity) and laboratory parameters (C‐reactive protein level and erythrocyte sedimentation rate). Results were compared for patients with and without re‐therapy with RTX. Results Significant decreases in clinical and laboratory parameters were observed after 6 and 12 months. US synovitis scores significantly decreased after 6 and 12 months (P < 0.05 for each). Regarding patients who received re‐therapy between 6 and 9 months after the start of therapy (n = 9), a fair therapy response was still detectable before re‐therapy. In these patients, PD‐positive synovitis was the only parameter that increased up to the 6‐month examination. All patients negative for rheumatoid factor and anti–cyclic citrullinated peptide (n = 4) were in the group of patients receiving a second course of treatment. Seropositive patients showed a better response to treatment with less need for re‐therapy. Conclusion Response to therapy was measurable by clinical and laboratory parameters as well as by US. Since PDUS was able to detect the onset of disease activity before worsening of clinical symptoms occurred, PDUS is most helpful in evaluating disease activity and making earlier therapy decisions.