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Undifferentiated arthritis characteristics and outcomes when applying the 2010 and 1987 criteria for rheumatoid arthritis
  1. A Krabben,
  2. T W J Huizinga,
  3. A H M van der Helm-van Mil
  1. Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands
  1. Correspondence to A Krabben, Department of Rheumatology, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands; a.krabben{at}


Objective Undifferentiated arthritis (UA) is a diagnosis ‘per exclusionem’. Therefore this patient population may change since the development of the ACR/EULAR 2010-criteria for RA. This study evaluated characteristics and outcomes of UA in its new shape. Second, it was evaluated whether the 2010-criteria and the Leiden prediction rule were congruent in categorizing UA-patients.

Methods 2,472 early arthritis patients were studied. RA was classified according to either the 1987 or the 2010-criteria. UA was defined as not fulfilling existing classification criteria. UA-patients were compared for baseline characteristics and outcomes. In 1987-UA-patients both the 2010-criteria and the Leiden prediction rule were applied and categorization compared.

Results 2010-UA-patients (n=776) had milder baseline characteristics than 1987-UA-patients (n=1,166). During follow-up, still 24% of the 2010-UA-patients fulfilled the 1987 RA-criteria compared to 32% of the 1987-UA-patients. The 2010-UA-patients started less frequent DMARD-therapy and reached more frequent sustained DMARD-free remission. 30% of 2010-criteria-positive patients were predicted to have a low risk on RA; these patients achieved more frequent DMARD-free sustained remission than other 2010-criteria-positive patients.

Conclusion UA in the era of the 2010-criteria is less prevalent and milder at presentation and in outcome. This implies that UA-patients with unfavorable characteristics are now more often classified as RA.

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  • Funding The work of AK is supported by a grant from the Dutch Arthritis Foundation. The work of AHMvdHvM is supported by a grant from the Dutch organisation of Health Research and Development. The research has been funded by the European Community Seventh Framework Program FP7 Health-F2-2008–223404 (Masterswitch) and by a core grant from the Dutch Arthritis Foundation.

  • Competing interests None.

  • Patient consent Obtained.

  • Ethics approval The study was approved by the local medical ethics committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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