Objective Performance of the 2010 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) rheumatoid arthritis (RA) criteria was analysed in an internationally recruited early arthritis cohort (≤16 weeks symptom duration) enrolled in the ‘Stop-Arthritis-Very-Early’ trial. This sample includes patients with a variety of diseases diagnosed during follow-up.

Methods Two endpoints were defined: Investigators’ diagnosis and disease-modifying antirheumatic drug (DMARD) treatment start during the 12-month follow-up. The 2010 criteria were applied to score Patients’ baseline data. Sensitivity, specificity, predictive values and areas under the receiver operating curves of this scoring with respect to both endpoints were calculated and compared to the 1987 criteria. The optimum level of agreement between the endpoints and the 2010 classification score ways estimated by Cohen’s ϰ coefficients.

Results 303 patients had 12-months follow-up. Positive predictive values of the 2010 criteria were 0.68 and 0.71 for RA-diagnosis and DMARD-start, respectively. Sensitivity for RA-diagnosis was 0.85, for DMARD-start 0.8, whereas the 1987 criteria’s sensitivities were 0.65 and 0.55. The areas under the receiver operating curves of the 2010 criteria for RA-diagnosis and DMARD-start were 0.83 and 0.78. Analysis of inter-rater-agreement using Cohen’s ϰ demonstrated the highest ϰ values (0.5 for RA-diagnosis and 0.43 for DMARD-start) for the score of 6.

Conclusions In this international very early arthritis cohort predictive and discriminative abilities of the 2010 ACR/EULAR classification criteria were satisfactory and substantially superior to the ‘old’ 1987 classification criteria. This easier classification of RA in early stages will allow targeting truly early disease stages with appropriate therapy.