Musculoskeletal Ultrasound and the Decision to Switch Therapy in Patients With Established Rheumatoid Arthritis

Introduction  Musculoskeletal ultrasound (MSUS) with power Doppler ultrasound (PDUS) or gray-scale ultrasound (GSUS) has been increasingly used to detect active synovitis. This study evaluated PDUS/GSUS scores and clinical disease activity scores in patients with established rheumatoid arthritis (RA) whose rheumatologist was considering a therapy switch. Methods  Thirty-two patients with RA were enrolled. Clinical Disease Activity Index (CDAI), Disease Activity Score-28 (DAS28), and PDUS/GSUS scores were obtained. Pearson correlation coefficients were used to evaluate the relationship of PDUS-24 and GSUS-24 with clinical composite measures. Demographics, disease activity measures, MSUS scores, and patient-reported outcomes were examined between switchers and non-switchers. Results  Of the 32 patients enrolled, 59% (n=19) switched therapy. Switchers had numerically higher DAS28, CDAI, CRP/ESR, and PDUS/GSUS scores, but these metrics were not statistically significantly different from those of non-switchers. Among patients with concordant findings, 80% (n=8/10) of those with DAS28 ≥3.2 and high PDUS (>5) switched therapy, whereas only 25% (n=1/4) of patients with DAS28 <3.2 and low PDUS (≤5) did so. In the discordant group, therapy was switched in 60% of patients with high DAS28/low PDUS (n=6/10) and 60% of those with low DAS28/high PDUS (n=3/5). Physician global assessment and physician-reported RA flare were higher among therapy switchers (t(29) = -2.96, p=0.006; and Fisher's exact p=0.03, respectively). Non-switchers were more satisfied with their treatment compared to switchers (8.8 vs 5.3, t(30) = 4.42, p<0.001). Conclusion  Among patients with established RA, disease-modifying antirheumatic drug (DMARD) switchers had numerically higher CDAI, DAS28, and PDUS/GSUS scores compared with non-switchers. Eighty percent of patients with both increased DAS28 and PDUS switched therapy, compared with 60% of those with discordant findings, including high DAS28/low PDUS and vice versa. The PDUS/DAS28-discordant population faces inherently difficult therapeutic decisions and highlights the lack of guidance for physicians and patients.