Background A comprehensive diagnosis of rheumatoid arthritis (RA) is made on the basis of immunological and morphological abnormalities. However, the 2010 American College of Rheumatology (ACR) – European League Against Rheumatism (EULAR) RA classification criteria depend heavily on serological markers and not morphologic imaging findings.
Objectives We assessed the role of ultrasound (US) in the diagnosis of early RA when the new criteria were applied clinically.
Methods We studied 128 patients who first visited our department with arthralgia. We categorized the patients into two groups based on clinical outcome 1 year later: patients treated with anti-rheumatic therapies were placed in the RA group, and the remaining patients constituted the non-RA group. Ten joints (bilaterally, the second and third MCPs and second PIPs of the fingers, wrists and knees) were evaluated at study entry by using gray-scale (GS) and power Doppler (PD), with semi-quantitative grading from 0 to 3. Total GS and PD scores (i.e. the sums of the grades in the 10 joints) were also compared. We also examined whether individual patients met the 1987 ACR RA classification criteria and the 2010 ACR/EULAR criteria.
Results Anti-rheumatic drugs, including methotrexate and salazosulfapyridine, were initiated in 54 patients (RA group). The remaining 74 (non-RA group) consisted of 24 (32.4%) with undifferentiated arthritis, 13 (17.5%) with osteoarthritis, and the remainder with other diseases. At entry, 48 of the 54 RA patients (88.8%) fulfilled the 2010 ACR/EULAR criteria, whereas only 36 of 54 patients (66.7%) fulfilled the 1987 ACR criteria. Clinical findings and US findings at entry were compared between the two groups. Compared with the non-RA group, the RA group had significantly greater numbers of swollen and tender joints, significantly greater serum levels of C-reactive protein, and significantly higher frequencies of rheumatoid factor (RF) and anti-cyclic-citrullinated-peptide (CCP) antibody positivity (p<0.01). The proportion of patients with abnormal findings and the total GS and PD scores on US were also significantly higher in the RA group (P<0.05 and P<0.01, respectively). In all 6 patients in the RA group who did not meet the 2010 ACR–EULAR criteria at entry, active synovitis was proven by US. In contrast, one patient who had no proven synovitis on US and who was classified into the non-RA group, despite high titers of both RF and anti-CCP antibody, did not develop clinical manifestations of RA during the observation period.
Conclusions US is useful for the diagnosis of RA, especially in patients without disease-associated autoantibodies. Its use may also help to avoid unnecessary treatment of patients with positive serological markers but no synovitis. Our findings suggest that US provides morphological information that is essential for the diagnosis of RA but is not included in the new criteria.
Disclosure of Interest None Declared