Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Do the New EULAR/ACR Rheumatoid Arthritis Classification Criteria Identify Early Psoriatic Arthritis Patients?

Coates2,  Laura C., Conaghan2,  Philip G., Emery2,  Paul, Green3,  Michael J., Ibrahim1,  Gamal, MakIver1,  Helen, Helliwell2,  Philip S.

Bradford Hospitals NHS Trust, UK, Bradford, United Kingdom
LIMM, Section of Musculoskeletal Disease, University of Leeds, Leeds, UK
York Hospitals NHS Trust, York, UK

Background:

The new ACR-EULAR classification criteria for rheumatoid arthritis (RA) have been developed to enable an early identification of patients with RA. They were tested during development in undifferentiated arthritis populations. The aim of this study was to investigate whether the new ACR/EULAR criteria for early RA are robust in excluding PsA and whether any patients would meet both these criteria and PsA classification criteria.

Methods:

The new ACR/EULAR criteria for early RA and the Moll&Wright and CASPAR criteria for PsA were applied to cases of early PsA (less than 24 months symptom duration) early RA and other forms of early inflammatory arthritis who were all disease-modifying anti-rheumatic drug naive. Gold standard diagnosis was confirmed by a consultant rheumatologist. All joints required for the ACR/EULAR criteria were assessed.

Results:

111 early PsA cases, 82 early RA cases and 29 other early arthritis controls (undifferentiated arthritis n=13, spondyloarthritis n=9, inflamm OA n=4, crystal arthritis n=3) were recruited. The sensitivity of the ACR/EULAR criteria (score >=6) in classifying early RA was 91%. The specificity for the criteria when considering all other diagnoses was 53%. When considering the specificity only for PsA, it was lower at 48%. When comparing classification criteria for RA and PsA, none of the RA patients met the PsA criteria (either Moll&Wright or CASPAR), and only 1 of the other inflammatory arthritis patients fulfilled these criteria. The majority of PsA patients who met the RA classification criteria also met a PsA classification criteria.

ACR/EULAR criteria components (%)Early PsA (n=111)Early RA (n=82)Other controls (n=29)
Synovitis of at least 1 joint929683
1 large joint only465045
2–10 large joints534659
1–3 small joints231128
4–10 small joints413735
>10 joints including 1 small30607
Neg RF and ACPA942079
Low positive RF or ACPA41014
High positive RF or ACPA3717
Duration >=6 weeks999883
Raised CRP or ESR487763
 Early PsA (n=111)Early RA (n=82)Other controls (n=29)
Met ACR/EULAR criteria529228
Met CASPAR criteria8703
Met Moll&Wright criteria8003
Met ACR/EULAR criteria AND Moll&Wright criteria3900
Met ACR/EULAR criteria AND CASPAR criteria4300

Conclusion:

The new ACR/EULAR criteria are sensitive at identifying early RA but are not specific when considering psoriatic arthritis. The majority of PsA patients met the criteria due to high joint counts despite having negative immunology. The ACR/EULAR criteria must be used with caution in an early arthritis population particularly when patients have evidence of skin or nail psoriasis.

To cite this abstract, please use the following information:
Coates, Laura C., Conaghan, Philip G., Emery, Paul, Green, Michael J., Ibrahim, Gamal, MakIver, Helen, et al; Do the New EULAR/ACR Rheumatoid Arthritis Classification Criteria Identify Early Psoriatic Arthritis Patients? [abstract]. Arthritis Rheum 2010;62 Suppl 10 :2182
DOI: 10.1002/art.29946

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