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.


A Prediction Score To Differentiate Rheumatoid Arthritis from Undifferentiated Arthritis in an Early Arthritis Cohort.

Waimann2,  Christian, DalPra2,  Fernando, Hogrefe2,  Jimena, Marcos2,  Josefina, Retamozo2,  Soledad, Caeiro2,  Francisco, Casalla2,  Luciana

CONAART, Buenos Aires, Argentina
CONAART, Argentina

Objective:

to identify predictor factors for progression into rheumatoid arthritis (RA) in patients with undifferentiated arthritis (UA).

Methods:

A prediction score was developed using data from CONAART (Argentine Consortium for Early Arthritis), the first early arthritis cohort in Argentina (n=714). Patients with at least one swollen joint and less than 2 years of symptoms duration were followed for 6 months. The clinical characteristics associated with RA in univariate analysis were later selected using a logistic regression model. A weighted score was set according to strength of association (odds ratio: OR) of main variables as follows (OR 1 to 2=1 point, OR 2.1 to 4=2 points, OR 4.1 to 8=3 points and OR > 8=4 points), given a total score from 0 to 20. A prediction score of 7 variables (tender and swollen joint count, symmetric involvement, acute phase reactants, rheumatoid factor (RF) positivity and anti-CCP positivity) was obtained. Categorical variables were compared using chi square and Fisher exact test and continue variables using student T test and ANOVA. The discriminative ability of the score to differentiate RA from UA was evaluated using the area under the curve (AUC). Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for different cut-off points of the score were calculated.

Results:

619 patients were included (UA=312, RA=307), 515 (83.2%) were women, median age 47 years, median disease duration 6 months. Patients with RA had significantly higher disease activity (DAS28), and worse functional capacity and quality of life compared to UA patients. In the logistic regression analysis, the independent predictive variables for development of RA and their corresponding score were: more than 5 tender joints = 3 points, more than 4 swollen joints = 3 points, symmetric involvement = 2 points, ESR > 22.5 mm/h = 1 point, C-Reactive protein > 8.5 mg/L = 3 points, RF positive = 4 points, Anti CCP positive = 4 points. The AUC value of the score was 0.84 (95% CI: 0.80–0.87). A cut-off value of 9 had sensitivity of 80% and specificity of 81.4%, PPV of 82% and NPV of 81.4% to differentiate RA from UA. The validation of the van der Helm van Mil (A&R 2007;52:433–440) prediction rule in our population showed an AUC of 0.80 (95%CI 0.76–0.83).

Conclusion:

The present score had an excellent ability to discriminate between RA and UA using simple variables obtained from daily practice.

To cite this abstract, please use the following information:
Waimann, Christian, DalPra, Fernando, Hogrefe, Jimena, Marcos, Josefina, Retamozo, Soledad, Caeiro, Francisco, et al; A Prediction Score To Differentiate Rheumatoid Arthritis from Undifferentiated Arthritis in an Early Arthritis Cohort. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :50
DOI: 10.1002/art.27819

Abstract Supplement

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