Background 2010 ACR/EULAR RA classification criteria refer to a possible use of new imaging techniques such as ultrasonography (US). However, the impact of US assessment on the accuracy of the criteria to classify diseases that require methotrexate (MTX) treatment has not been fully assessed.
Objectives To determine the impact of US assessment of synovitis on the accuracy of 2010 ACR/EULAR RA classification criteria to classify diseases that require MTX treatment.
Methods 117 consecutive cases with musculoskeletal symptoms for less than three years which were not obviously explained by diseases other than RA were enrolled in the study. Patients underwent full assessment including ultrasound (US) on 38 joint regions at baseline and received routine care from expert rheumatologists who were blinded to the ultrasound findings. For simple description, joints with GS score ≥1 or PD score ≥1 were defined as having US-synovitis, whereas those with swelling or tenderness were defined as having clinical (CL)-synovitis. Similarly, patients who were classified as RA when joint assessment was replaced with US-synovitis were defined as having US-RA, whereas those who were classified as RA without US assessment were defined as having CL-RA.
Results Proportions of cases who received MTX for RA treatment during study period were 17.0% for CL-RA (-) US-RA (-) patients (N=47), 8.3% for CL-RA (+) US-RA (-) patients (N=12), 60.0% for CL-RA (-) US-RA (+) patients (N=10), and 79.1% for CL-RA (+) US-RA (+) patients (N=43). The proportion was significantly higher in CL-RA (-) US-RA (+) patients than CL-RA (+) US-RA (-) patients (Fisher’s exact test, P=0.008). The sensitivity and the specificity of 2010 ACR/EULAR RA classification criteria to predict MTX-requirement within the first year of classification were 71.4% and 68.2%, respectively. When US-synovitis was applied, not only the sensitivity, but also the specificity of the criteria improved (81.6% and 79.3%, respectively). Receiver operating characteristic (ROC) curves for the criteria scores to predict an MTX-requiring disease demonstrated a larger area under curve (AUC) for the score with US-synovitis than that with CL-synovitis (Figure).
Conclusions Ultrasonographic assessment of synovitis improves both the sensitivity and the specificity of 2010 ACR/EULAR classification criteria for RA to predict development of an MTX-requiring disease.
Disclosure of Interest None Declared
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