RESEARCH - Validation of a prediction rule for development of RA in patients with early undifferentiated arthritis

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Ann Rheum Dis. Published Online First: 17 November 2008.

doi:10.1136/ard.2008.092676

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Concise Report

Validation of a prediction rule for development of rheumatoid

arthritis in patients with early undifferentiated arthritis

Bindee Kuriya 1*, Carly K Cheng 1, Hong M Chen 1 and Vivian P Bykerk 1

1 University of Toronto, Canada

Abstract

Objective: A model to predict progression from undifferentiated

arthritis (UA) to RA was recently created. This study aimed to

validate the model in a Canadian UA cohort.

Methods: The prediction rule consists of variables, which are scored

(range 0-13), with higher scores reflecting an increased risk of RA.

The model was applied to baseline characteristics of all UA patients.

Progression to RA was determined at 6 months.

Results: Overall, 105 patients were identified. By 6 months, 80 (76%)

developed RA while 25 (24%) developed another diagnosis. The number of

tender and swollen joints, RF positivity, anti-CCP positivity, poor

functional status and high disease activity were associated with

development of RA (p < 0.01). Among progressors, the median prediction

score was 8.0 while non-progressors had a median score of 5.0. Using

these cutoffs, 18 (72%) patients with scores 5 did not develop RA

while 35 (97%) of patients with scores 8 did develop RA.

Conclusions: High scores in our cohort predicted those who progressed

to RA by 6 months. Baseline scores 8 corresponded with higher rates

of progression, validating the original prediction model. Future

research should focus on how to predict disease outcome and response

to therapy among patients with intermediary scores.

http://ard.bmj.com/cgi/content/abstract/ard.2008.092676v1?papetoc

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