Performance of the 2010 ACR/EULAR classification criteria for rheumatoid arthritis in a prospective early arthritis cohort in Kerala, India

Abstract

ObjectivesIn this prospective study we evaluated (i) whether the 2010 ACR/EULAR criteria would include patients who were classified as early rheumatoid arthritis (RA) according to the 1987 ACR criteria, and (ii) outcome by classification of patients who were initially classified as undifferentiated arthritis (UA). MethodsEligible cohort (all patients with at least one clinically swollen joint) consisted of 134 patients, of which 120 had clinical diagnosis of RA. All patients were classified using both 1987 and the 2010 criteria at the beginning of the study and 1 year later. ResultsOut of 134 eligible patients 102 were classified as RA based on 1987 criteria. A total of 82 (80%) out of 102 patients were seropositive for RA, i.e. positive for either rheumatoid factor (RF) or anti-citrullinated peptide antibody (ACPA). According to the 2010 criteria, 86 (84%) out of the 102 patients were classified as having RA. Among the 82 seropositive patients, only 1 (1.21%) patient was classified as not having RA whereas, among 20 patients who had seronegative (both for RF and ACPA) RA, 15 (75%) patients were not classified as RA according to the 2010 criteria. Sensitivity and specificity of the 2010 criteria was 96.67% and 92.86%, respectively, compared with 85% and 85.71% by 1987 criteria. 25% of initial UA patients were reclassified as RA by the 2010 criteria at 1 year. ConclusionsThe 2010 criteria did not identify a substantial proportion of seronegative RA classified by the 1987 criteria. Therefore due care must be taken when applying the new criteria to patients with arthritis who are seronegative.