New criteria to classify rheumatoid arthritis (RA) have been derived in order to increase the specificity and sensitivity for early RA compared with the 1987 American College of Rheumatology (ACR) criteria. The aim of this study was to evaluate differences in classification between the 1987 ACR criteria and the 2010 ACR/European League Against Rheumatism (EULAR) criteria in an early arthritis cohort and to determine the test characteristics of the 2010 ACR/EULAR criteria.
A total of 2,258 patients with early arthritis included in the Leiden Early Arthritis Clinic cohort were studied. Fulfillment of the 1987 and 2010 criteria for the classification of RA was determined at baseline. The diagnosis of each patient at 1 year was assessed. The sensitivity and specificity of the 2010 criteria were determined using the following outcome measures: initiation of methotrexate therapy or any disease-modifying antirheumatic drug (DMARD) therapy during the first year of followup and having persistent arthritis during 5 years of followup.
At their first presentation, 1,099 patients fulfilled the 2010 criteria, and 726 patients fulfilled the 1987 criteria for RA. Eighty-two of the 726 patients fulfilling the 1987 criteria did not fulfill the 2010 criteria. Sixty-eight percent of the patients who fulfilled the 1987 criteria during the first year of disease but not at baseline did fulfill the 2010 criteria at baseline. In 18% of patients, use of the 2010 classification criteria also led to a revoked classification at 1 year. The sensitivity and specificity of the 2010 criteria were 0.84 and 0.60, respectively, with methotrexate therapy as the outcome and 0.74 and 0.74, respectively, with DMARD therapy as the outcome. With persistent arthritis as the outcome, the sensitivity and specificity of the 2010 criteria were 0.71 and 0.65, respectively.
Compared with the 1987 criteria, the 2010 criteria classify more patients with RA and at an earlier phase of the disease. The discriminative ability of the 2010 criteria is acceptable.