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Abstract

OBJECTIVE.: Quantitative assessment of disease activity in rheumatoid arthritis (RA) is important for patient management, and additional objective information may aid rheumatologists in clinical decision-making. We validated a recently-developed multi-biomarker disease activity (MBDA) test relative to clinical disease activity in diverse RA cohorts. METHODS.: Serum samples were obtained from the InFoRM, BRASS, and Leiden Early Arthritis Clinic cohorts. Levels of 12 biomarkers were measured and combined according to a pre-specified algorithm to generate the composite MBDA score. The relationship of the MBDA score to clinical disease activity was characterized separately in seropositive and seronegative patients using Pearson correlations and area under the receiver operator characteristic curve (AUROC) to discriminate between patients with low and moderate/high disease activity. Associations between changes in MBDA score and clinical responses 6-12 weeks after initiation of anti-TNF or methotrexate treatment were evaluated by AUROC. RESULTS.: The MBDA score was significantly associated with DAS28-CRP in both seropositive (AUROC=0.77; P<0.001) and seronegative patients (AUROC=0.70; P<0.001). In subgroups based on age, sex, body-mass index, and treatment, the MBDA score was associated with DAS28-CRP (P<0.05) in all seropositive and most seronegative subgroups. Changes in MBDA score at 6-12 weeks could discriminate both ACR50 responses (P=0.03) and DAS28-CRP improvement (P=0.002). Changes in MBDA score at 2 weeks were also associated with subsequent DAS28-CRP response (P=0.02). CONCLUSION.: Our findings establish the criterion and discriminant validity of a novel multi-biomarker test as an objective measure of RA disease activity to aid in the management of RA patients.