To assess the role of musculoskeletal ultrasound (MSUS) as a biomarker of remission and to compare the rates of clinical and imaging remission in patients with rheumatoid arthritis (RA) on different types of treatment.
One hundred and forty-one patients underwent physical and ultrasound examination at 5 visits (at baseline and after 1, 3, 6 and 12 months). Patients were divided into two groups according to the type of treatment, which involved synthetic (sDMARDs) and biologic (bDMARDs) disease-modifying antirheumatic drugs. Ultrasound assessment of the wrist, second and third metacarpophalangeal, second and third proximal interphalangeal joints, and the second and fifth metatarsophalangeal joints was performed on gray scale ultrasound (GSUS) and on power Doppler ultrasound (PDUS) (German US7-score). The rate of imaging and clinical remission (DAS28, SDAI, CDAI, and Boolean) was established. The percentage of patients in clinical remission with persistent PD signal was assessed.
In the sDMARDs group at month twelve, 43.6% of the patients achieved DAS28 remission, 5.1% - SDAI, 3.8% - CDAI, and 3.8% - Boolean remission. In the bDMARDs group 49.2% achieved DAS28 remission, 6.3% - SDAI, 4.8% - CDAI, and 4.8% - Boolean remission. Irrespective of which clinical index was applied, all patients in clinical remission had persistent synovial hypertrophy on GSUS. Synovial PD signal (PDUS score≥1) was detected in 77% and 71% of patients in DAS28 remission in the sDMARDs and bDMARDs group, respectively. Patients in SDAI, CDAI and Boolean remission in both treatment groups did not have а positive PD signal.
There is persistence of synovitis both in patients on sDMARDs and bDMARDs in DAS28 clinical remission. This fact points to a discordance between DAS28 clinical remission and the imaging remission assessed by MSUS irrespective of the type of treatment. MSUS may be a feasible imaging method for the assessment of residual inflammation in daily rheumatology practice.