The additional benefit of ultrasonography to 2010 ACR/EULAR classification criteria when diagnosing rheumatoid arthritis in the absence of anti-cyclic citrullinated peptide antibodies

The aim of this study was to assess the benefit of ultrasonography (US) contributing to 2010 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) classification criteria in diagnosing rheumatoid arthritis (RA), when anti-citrullinated protein (CCP) antibody and radiographic erosions are absent. Ninety-four patients suffering from arthritis of at least one joint in hands, symptom duration of less than 2 years, normal radiographs at baseline, and negative anti-CCP had 22 joint US assessments and were followed prospectively for at least 12 months. Sensitivity and specificity for final RA diagnosis based on 1987 RA criteria were determined for ultrasound variables. Logistic regression models were then fitted to evaluate predictive ability over and above the 2010 ACR/EULAR classification criteria. Twenty-nine of them were classified as RA patients and 65 had alternative diagnoses. There were significantly more joints with synovial hypertrophy, synovitis, and bone erosion detected by US in RA patients. The gray-scale (GS) variables positively correlated with acute phase reactants. The area under curve (AUC) values of GS and power Doppler (PD) were comparable, higher than bone erosion. However, regression analysis demonstrated that only PD involvement of joints, especially wrists, provided independently predictive data, with improved AUC values from 0.738 to 0.872 combined with 2010 ACR/EULAR classification criteria. PD scanning of hand joints, especially wrists, may provide independently assistance to 2010 ACR/EULAR criteria in the early diagnosis of RA in those patients who are negative for anti-CCP antibody.