The effect of different remission definitions on identification of predictors of both point and sustained remission in rheumatoid arthritis treated with anti-TNF therapy.

OBJECTIVE: Predictors of remission in rheumatoid arthritis (RA) have been defined in cross-sectional analyses using the 28-joint Disease Activity Score (DAS28), but not with newer composite disease activity measures or using the more clinically relevant state of sustained remission. We have evaluated predictors of remission using cross-sectional and longitudinal durations of disease state, and by applying additional definitions of remission [American College of Rheumatology/European League Against Rheumatism Boolean, Simplified Disease Activity Index (SDAI), and Clinical Disease Activity Index (CDAI)].

METHODS: Individuals in the Alberta Biologics Pharmacosurveillance Program were classified for the presence of remission (point and/or sustained > 1 yr) by each of the 4 definitions. Multivariate models were constructed including all available variables in the dataset and refined to optimize model fit and predictive ability to calculate OR for remission.

RESULTS: Nonsmoking status independently predicted point remission by all definitions (OR range 1.20-2.71). Minority ethnicity decreased odds of remission by DAS28 (OR 0.13) and CDAI (OR 0.09) definitions. Male sex was associated with DAS28 remission (OR 2.85), whereas higher baseline physician global (OR 0.67) and erythrocyte sedimentation rate values (OR 0.98) decreased odds of DAS28 remission. Higher baseline patient global score (OR 0.77) and swollen joint counts (OR 0.93) were negative predictors for CDAI remission. Higher baseline Health Assessment Questionnaire (OR 0.62) reduced odds for remission by the SDAI definition, and educational attainment increased these odds (OR 2.13). Sustained remission was negatively predicted by baseline physician global for the DAS28 (OR 0.80), and higher tender joint count (OR 0.96) for the CDAI.

CONCLUSION: We demonstrate the influence of duration of remission state and remission definition on defining independent predictors for remission in RA requiring anti-tumor necrosis factor therapy. These predictors offer improved applicability for modern rheumatology practice.