Objective: More timely and effective therapy for rheumatoid arthritis (RA) has contributed to increasing rates of clinical remission. However, progression of structural damage may still occur in patients who have satisfied remission criteria, which suggests that there is ongoing disease activity. This questions the validity of current methods of assessing remission in RA. The purpose of this study was to test the hypothesis that modern joint imaging improves the accuracy of remission measurement in RA.

Methods: We studied 107 RA patients receiving disease-modifying antirheumatic drug therapy who were judged by their consultant rheumatologist to be in remission and 17 normal control subjects. Patients underwent clinical, laboratory, functional, and quality of life assessments. The Disease Activity Score 28-joint assessment and the American College of Rheumatology remission criteria, together with strict clinical definitions of remission, were applied. Imaging of the hands and wrists using standardized acquisition and scoring techniques with conventional 1.5T magnetic resonance imaging (MRI) and ultrasonography (US) were performed.

Results: Irrespective of which clinical criteria were applied to determine remission, the majority of patients continued to have evidence of active inflammation, as shown by findings on the imaging assessments. Even in asymptomatic patients with clinically normal joints, MRI showed that 96% had synovitis and 46% had bone marrow edema, and US showed that 73% had gray-scale synovial hypertrophy and 43% had increased power Doppler signal. Only mild synovial thickening was seen in 3 of the control subjects (18%), but no bone marrow edema.

Conclusion: Most RA patients who satisfied the remission criteria with normal findings on clinical and laboratory studies had imaging-detected synovitis. This subclinical inflammation may explain the observed discrepancy between disease activity and outcome in RA. Imaging assessment may be necessary for the accurate evaluation of disease status and, in particular, for the definition of true remission.