Thresholds for the 28-joint disease activity score (DAS28) using C-reactive protein are lower compared to DAS28 using erythrocyte sedimentation rate in early rheumatoid arthritis.

OBJECTIVES: The 28-Joint Disease Activity Score (DAS28) using C-reactive protein (CRP) and DAS28 using erythrocyte sedimentation rate (DAS28-ESR) may not be interchangeable. We sought to compare and estimate optimal thresholds for the DA28-CRP for use in early rheumatoid arthritis (ERA). METHODS: Patients from the Canadian Early Arthritis Cohort with baseline and 12 months' data for both DAS28-ESR and DAS28-CRP were examined for correlations and differences between DAS28-CRP and DAS28-ESR across their range of values. Receiver operating characteristic analysis identified thresholds for DAS28-CRP that best corresponded to established thresholds for the DAS28-ESR using the total sample, then stratified by age and sex. Agreement between DAS28-CRP and DAS28-ESR thresholds was assessed with the kappa statistic. RESULTS: The sample included 995 patients with mean (SD) age of 53.7 (14.5) years, 5.8 (2.9) months of symptom duration and 74% were female. DAS28-CRP and DAS28-ESR scores were highly correlated (r= 0.92, p<0.0001), however DAS28-CRP values were consistently lower than DAS28-ESR values. Calculated thresholds for DAS28-CRP were lower with 2.5 for remission, 2.9 for low disease activity, and 4.6 for high disease activity but showed moderate agreement with the DAS28-ESR thresholds (kappa=0.70). CONCLUSIONS: In this large sample of ERA patients, newly estimated thresholds for DAS28-CRP were consistently lower than DAS28-ESR thresholds across the spectrum of disease activity. This may have important clinical implications if inflammatory markers are used interchangeably. Additional external validation of our findings is needed.

Earlier time to remission predicts sustained clinical remission in early rheumatoid arthritis--results from the Canadian Early Arthritis Cohort (CATCH).

OBJECTIVE: To evaluate the prevalence and predictive factors of sustained remission in an early rheumatoid arthritis (ERA) population. Predictive factors of sustained remission in ERA are unknown. We hypothesized that a short time to remission is an important predictor of sustained clinical remission. METHODS: Patients in the Canadian Early Arthritis Cohort were included. Remission was defined by Boolean-based American College of Rheumatology/European League Against Rheumatism clinical trial and clinical practice definitions and Simplified Disease Activity Index (SDAI). Logistic regression analysis identified predictors of sustained remission and influence of time to remission. RESULTS: Of 1840 patients, 633 (34%) achieved clinical trial remission, 759 (41%) clinical practice remission, and 727 (39%) SDAI remission. Over half of those meeting remission criteria achieved sustained remission based on clinical trial (55%), clinical practice (60%), and/or SDAI (58%). Corticosteroid use and lack of initial disease-modifying antirheumatic drug (DMARD) were associated with decreased probability of sustained remission, while initial combination DMARD increased this probability. Female sex, greater pain, and longer time to first remission made sustained remission less likely. CONCLUSION: Female sex, greater pain, and lack of initial DMARD therapy reduced the probability of sustained remission. A shorter time to remission is related to sustainability and supports striving for early remission.