Towards a data-driven evaluation of the 2010 ACR/EULAR criteria for rheumatoid arthritis: Is it sensible to look at levels of rheumatoid factor?

Abstract

OBJECTIVE:: Recently new classification criteria for Rheumatoid Arthritis (RA) have been devised by methodology that used first a quantitative approach (data from databases), then a qualitative approach (consensus-based on paper patients) and finally a common sense based approach (evaluation of the former phases). Now these criteria are being evaluated to assess characteristics of the individual items. This study analyzed characteristics of the item autoantibodies, in particular RF-level. METHODS:: Three separate cohorts with a total of 972 undifferentiated arthritis patients were studied for RA-development (according to the 1987 ACR criteria) and arthritis persistency. Positive and negative predictive values (PPV, NPV) and likelihood ratios (LR) were compared between different levels of RF and the presence of ACPA. A similar comparison was made in 686 RA-patients for the rate of joint destruction during 7 years of follow-up and achievement of sustained-DMARD-free-remission. The variation in RF-levels obtained by different measurement methods in the same RF-positive sera was explored. RESULTS:: Presence of ACPA had a better balance between LR+/LR- and PPV/NPV than high RF-levels for RA-development. The additive value of ACPA assessment after high level RF-testing was higher than vice versa. High level RF was less strongly associated with RA-severity than ACPA-antibodies. The RF-level obtained by different methods in the same patients' sera varied considerably. CONCLUSION:: Level determination of RF is subject to large variation; high level RF has limited additive prognostic value compared to ACPA-positivity. Thus, omitting RF level and using RF-presence, ACPA-presence and ACPA-level may improve the 2010 criteria for RA.