Study data published in Clinical Rheumatology support the discriminatory capacity of the European League Against Rheumatism (EULAR) definition of arthralgias suspicious for progression to rheumatoid arthritis (RA). In a cohort of patients with hand arthralgias, the EULAR criteria, combined with ultrasound and laboratory data, correctly classified 92% of cases with RA.
Investigators conducted a prospective cohort study of adults older than 18 years with hand arthralgias between August 2017 and July 2019. At baseline, patients underwent an ultrasound (US) with power Doppler (PD) of both hands and radiography of the hands and feet. Laboratory tests were used to determine erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) levels, rheumatoid factor (RF) positivity, and anti-cyclic citrullinated peptide antibodies (ACPA) positivity. Patients were followed by their treating rheumatologists; the primary outcome was diagnosis of RA per 2010 EULAR criteria. The area under the receiving operator curve (AUC) was used to evaluate the diagnostic performance of EULAR criteria for arthralgias likely to progress to RA. Multivariate logistic regression analyses were performed to identify baseline predictors of RA development. The EULAR definition for suspicious arthralgias includes 7 features; EULAR risk was expressed as the number of features observed in each patient.
The study cohort comprised 465 patients with hand arthralgias, among whom 358 (76.9%) were women. Mean age at baseline was 53.8±14.5 years. During follow-up, 44 patients (9.4%) were diagnosed with RA by their treating rheumatologists. Mean baseline number of EULAR features was 4.1±1.6 in patients who were later diagnosed with RA vs 2.3±1.5 in patients without RA (P <.0001). RF, ACPA, and the presence of synovitis by US with PD were more commonly observed in the RA vs the non-RA group.
The AUC for EULAR features for final diagnosis of RA was 0.7827 (95% CI, 0.7150-0.8503), indicating modest discrimination. When US with PD, RF, and ACPA data were added to EULAR features, the AUC increased to 0.9172 (95% CI, 0.8794-0.9550; P <.001). In the final model, the best cutoff for number of EULAR-defined features was ≥ 4, which had a sensitivity of 90.9% and a specificity of 76.5%.
In multivariate regression, baseline features associated with later diagnosis of RA included difficulty making a fist (odds ratio [OR], 60.3; 95% CI, 3.6-1004), RF positivity (OR, 111.7; 95% CI, 9.9-1252), ACPA positivity (OR, 220.8; 95% CI, 12.3-3956), and US with PD in at least 1 joint (OR, 117.4; 95% CI, 8.8-1553).
The EULAR definition of arthralgia suspicious for progression to RA performed well in distinguishing patients who were later diagnosed with RA from patients who were not. The addition of other laboratory features to the EULAR prediction model increased discrimination. Overall, EULAR features appear to be useful for identifying RA risk in patients with hand arthralgias.
Ruta S, Prado ES, Chichande JT, et al. EULAR definition of “arthralgia suspicious for progression to rheumatoid arthritis” in a large cohort of patients included in a program for rapid diagnosis: role of auto-antibodies and ultrasound. Clin Rheumatol. 2020;39:1493-1499.