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 Longitudinal Trivariate Model of Disease Activity Score, Physical Function and Radiographic Damage: Results from SONORA Study.

Chen1,  Maggie, Li1,  Xiuying, Akhavan2,  Pooneh, Bombardier3,  Claire

University Health Network
University of Toronto, University Health Network
University of Toronto, University Health Network, Mount Sinai Hospital, Toronto, ON, Canada

Purpose:

Rheumatoid arthritis (RA) affects approximately 1% of adults in North America. Active disease leads to radiographic damage and poor physical function. The purpose of this study is to demonstrate the use of a novel longitudinal trivariate model to identify simultaneously common significant predictors for three important outcomes in RA: Disease Activity Score (DAS); physical function measured with the Health Assessment Questionnaire (HAQ) and radiographic damage (Sharp Score).

Method:

994 Patients diagnosed as having new onset RA (symptoms >=3 but <=12 months) by a board-certified rheumatologist were recruited from 98 rheumatology practices. Clinical, laboratory, X-ray and health questionnaire data were collected by the enrolling rheumatologist at baseline, year 1 and year 2. A trivariate longitudinal model of DAS28, HAQ and sharp score was constructed and estimated using pooled cross sections for two years period, adjusting the significant predictors from the univariate analysis at the same time allowing for the latent individual-level effect. Different covariance structures were tested for the assumptions among these three outcomes in the model.

Results:

The mean age of patients was 53 years (SD, 14.8), with 72% female and 90% Caucasian. The mean RA symptom duration was 170 days (180). The DAS28, HAQ and Sharp score were 4.4(1.32), 1(0.73) and 5.01 (7.28) at baseline, 3.4(1.38), 0.82(0.71) and 6.19(8.73) at year 1, 3.2(1.34), 0.77(0.72) and 6.39(9.25) at year 2, respectively. Partial correlation adjusting for time point showed that DAS, HAQ and Sharp score are significantly correlated (all p-values <0.001). The longitudinal trivariate model showed that only higher baseline DAS, HAQ or Sharp Score value (P<0.0001), higher 28 swollen joint count (P<0.0001), longer disease duration (P=0.002) and lower house hold income (P=0.015) were significant predictors for these three combined outcomes.

Conclusion:

This innovative method identified the significant common predictors for three outcomes which related to the different aspects of RA patients. This method can help us better understand the longitudinally complex relationship between different aspects from a broader view of the disease. These identified factors can help rheumatologists to identify the patients who are at greater risk of worsen disease, physical function and radiographic damage and make treatment decisions for RA patients at the early stage.

To cite this abstract, please use the following information:
Chen, Maggie, Li, Xiuying, Akhavan, Pooneh, Bombardier, Claire; A Longitudinal Trivariate Model of Disease Activity Score, Physical Function and Radiographic Damage: Results from SONORA Study. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1734
DOI: 10.1002/art.29499

Abstract Supplement

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