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.


The CASPAR Criteria Can Be Used To Identify Early Psoriatic Arthritis.

Coates2,  Laura C., Conaghan3,  Philip G., Emery3,  Paul, Green4,  Michael J., Ibrahim1,  Gamal, MakIver1,  Helen, Helliwell3,  Philip S.

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

Background:

The classification of psoriatic arthritis (CASPAR) criteria were derived from a large patient dataset and have been shown to be valid in classifying established PsA (sensitivity 91.4%, specificity 98.7%). However in the original study, only 5% of the cohort had early disease (less than 12 months disease duration). The aim of this study was to assess the sensitivity and specificity of the CASPAR criteria in classifying early psoriatic arthritis and to compare the results to that of the Moll & Wright criteria.

Methods:

The CASPAR criteria were applied to cases of early PsA (less than 24 months symptom duration) and controls with other forms of early inflammatory arthritis who were all disease-modifying anti-rheumatic drug naive. Gold standard diagnosis was confirmed by a consultant rheumatologist. Proportions of cases and controls meeting the criteria were compared using McNemars test. Receiver operator characteristic (ROC) curve analysis was performed to identify the area under the curve (AUC) and optimal cut point in the CASPAR criteria for a diagnosis of early PsA. Logistic regression was performed to identify which features were associated with PsA.

Results:

111 early PsA cases and 111 early arthritis controls (RA n=82, undifferentiated arthritis n=13, spondyloarthritis n=9, inflamm OA n=4, crystal arthritis n=3) were recruited. The sensitivity of the CASPAR criteria (score >=3) in classifying early PsA was 87.4% compared to 80.2% for the Moll and Wright criteria. The specificity for both criteria was 99.1%, with only 1 control patient fulfilling both criteria for PsA. The AUC for the CASPAR criteria was 0.991 compared to 0.896 for the Moll & Wright criteria. When considering different cut-points for the CASPAR criteria, the best cut-point for classification remained a score of >=3 as in the original CASPAR analysis. Considering a score of >=2 gave a higher sensitivity of 99.1% but resulted in a drop in specificity to 94.6%.

When considering the individual components of the CASPAR criteria, 96.4% of cases had current, previous or a family history of psoriasis with 84% having current psoriasis. Dactylitis and nail psoriasis were highly discriminatory as only 1 control patient each had these features. Regression analysis identified that psoriasis and a negative RF were the most important features to differentiate PsA, followed by nail psoriasis and the presence of dactylitis.

CASPAR Features of PsACases (n=111)Controls (n=111)
Current psoriasis (%)844
Previous psoriasis (%)61
Family history of psoriasis (%)188
Nail psoriasis (%)381
Negative Rheumatoid factor (%)9647
Dactylitis (%)281
New bone formation (%)20

Conclusion:

The CASPAR criteria are more sensitive than the Moll & Wright criteria in classifying early PsA. Although the sensitivity is slightly lower than that in established disease, the CASPAR criteria are valid for use as inclusion criteria for early psoriatic arthritis trials.

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; The CASPAR Criteria Can Be Used To Identify Early Psoriatic Arthritis. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :2183
DOI: 10.1002/art.29947

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