Measured Factor Disease
- Disease remission
- High disease severity
Measured Factor Detail
The DAS28-CRP is utilized to determine the severity of disease in patients with confirmed rheumatoid arthritis. Using an assessment consisting of 28 joints, clinical and laboratory data, including tender joint count, swollen joint count, C-reactive protein, and global health, are obtained and are then utilized to determine DAS28-CRP using the following formula: DAS28-CRP = ( 0.56 x √(tender joint count) + 0.28 x √(swollen joint count) + 0.36 x ln(CRP + 1) + 0.014 x patient global + 0.96 ).
A DAS28-CRP of < 2.6 indicates disease remission.
A DAS28-CRP of ≥ 2.6 - < 3.2 indicates low disease severity.
A DAS28-CRP of ≥ 3.2 - ≤ 5.1 indicates moderate disease severity. A DAS28-CRP of > 5.1 indicates high disease severity.
Multiple body systems
DAS28-CRP = ( 0.56 x √(tender joint count) + 0.28 x √(swollen joint count) + 0.36 x ln(CRP + 1) + 0.014 x patient global + 0.96 )
Measured Factor Low Impact
Measured Factor High Impact
Normal Adult Male:
Normal Adult Female:
Normal Neonate Female:
Normal Geriatric Male:
Normal Geriatric Female:
Study Validation 1
Data were analysed from two randomised, double-blind, placebo-controlled trials of abatacept of 6-month and 12-month duration in patients with rheumatoid arthritis. European League Against Rheumatism (EULAR) response criteria and the proportion of patients in remission (DAS28 <2.6) based on the two DAS28 definitions were examined. Trends in radio graphic progression (erosion score, joint space narrowing score and total score) and physical function (Health Assessment Questionnaire Disability Index (HAQ-DI)) across the EULAR responder states (none, moderate and good) were analysed. There was general agreement in determining the EULAR responder state using both DAS28 definitions (κ=0.80, 95% CI 0.76 to 0.83). Overall, there was 82.4% agreement on the EULAR response criteria; when disagreements occurred, the DAS28 (CRP) yielded a better response more often then DAS28 (ESR) (12.6% vs 4.9%, respectively). There was also agreement in determining remission: κ=0.69 (95% CI 0.60 to 0.78). Radiographic progression decreased in patients treated with abatacept across EULAR states (from none to moderate to good) based on both definitions. For patients treated with placebo, the trend was not as pronounced, with radiographic scores higher for moderate vs. non-responders. For physical function, similar trends were observed across the EULAR states for both DAS28 definitions.
Study Validation 2
DAS28 data were analysed using a large observational study (Institute of Rheumatology Rheumatoid Arthritis) database of 6729 patients with rheumatoid arthritis. Firstly, the relationship between the DAS28-ESR and DAS28-CRP values was analysed. Secondly, the best DAS28-CRP trade-off values for each threshold were calculated using receiver operating characteristic (ROC) curves. The correlation coefficient of ESR versus CRP was 0.686, whereas that of DAS28-ESR versus DAS28-CRP was 0.946, showing the strong linear relationship between DAS28-ESR and DAS28-CRP values. DAS28-CRP threshold values corresponding to remission, low disease activity and high disease activity were 2.3, 2.7 and 4.1, respectively. The sensitivity and specificity from the ROC curves were gradually reduced as DAS28 values became lower. This study showed that DAS28-CRP and DAS28-ESR were well correlated, but the threshold values should be reconsidered.
Study Validation 3
This analysis included participants from the Consortium for the Longitudinal Evaluation of African Americans with Early Rheumatoid Arthritis (CLEAR) Registry which enrolled self-declared African-Americans with RA. Using tender and swollen joint counts separate ESR-based and CRP-based DAS28 scores (DAS28-ESR3 and DAS28-CRP3) were calculated, as were DAS28-ESR4 and DAS28-CRP4, which included the patient's assessment of disease activity. The scores were compared using paired t-test, simple agreement and kappa, correlation coefficient and Bland-Altman plots. Of the 233 included participants, 85% were women, mean age at enrollment was 52.6 years, and median disease duration at enrollment was 21 months. Mean DAS28-ESR3 was significantly higher than DAS28-CRP3 (4.8 vs. 3.9; p<0.001). Similarly, mean DAS28-ESR4 was significantly higher than DAS28-CRP4 (4.7 vs. 3.9; p<0.001). ESR-based DAS28 remained higher than CRP-based DAS28 even when stratified by age, sex, and disease duration. Overall agreement was not high between DAS28-ESR3 and DAS28-CRP3 (50%) or between DAS28-ESR4 and DAS28-CRP4 (59%). DAS28-CRP3 underestimated disease activity in 47% of the patients relative to DAS28-ESR3 and DAS28-CRP4 in 40% of the participants relative to DAS28-ESR4.
Study Additional 1
Patients with RA were included in a cross-sectional study. We have collected the demographic characteristics and the characteristics of the RA: duration of evolution, global disease activity on a 100 mm visual analogue scale assessed both by the patient (GDAP), morning stiffness in minutes, functional impact of the disease assessed by the HAQ (Health Assessment Questionnaire), and current corticosteroid dose. The disease activity was assessed by the DAS28-ESR and DAS28-CRP. A concordance correlation between DAS28-ESR and DAS28-CRP was performed. We defined a new variable DIFDAS=DAS28-ESR - DAS28-CRP (differences between the two indexes). Factors influencing this difference were tested by univariate then multivariate logistic regression. Using DAS28-ESR as gold standard, the passing Bablok and Bland- Altman methods were used to assess the agreement between DAS28-ESR and DAS28-CRP. 103 patients were included with a female predominance (87.4%). Mean age was 49.7 +/- 11.4 years. Median disease duration was 8 years [3-14]. There was a strong positive concordance between the two indexes of 0.93 with CI 95% [0.91-0.95], although the DAS28-ESR value obtained was higher than that of DAS28-CRP at approximately 90% of the visits (n=93). Significantly, the difference between both indexes was higher than 0.6 in 42.7% of the visits studied (n=44). In multivariate analysis, factors significantly associated with this difference were high dose steroids and significant functional impairment (p<0.05). There was a difference between DAS28-ESR and DAS28-CRP values (p<0.05). Using bland and Altman method, we found that DAS28-CRP under-estimate threshold values of DAS28-ESR by 0.49 with CI 95% [-1.96, +1.96].
Study Additional 2
A study comprising of 7023 patients from 30 countries in the Quantitative Standard Monitoring of Patients with RA (QUEST-RA) were analysed. Patient's global assessment of disease activity (PTGL) and general health (GH) determinants were assessed by mixed-effects analyses of covariance models. PTGL and GH equivalence was determined by Bland-Altman 95% limits of agreement (BALOA) and Lin's coefficient of concordance (LCC). Concordance between PTGL and GH based Disease Activity Score 28 (DAS28), Clinical Disease Activity Index (CDAI) and Routine Assessment of Patient Index Data 3 (RAPID3) indices were calculated using LCC, and the level of agreement in classifying RA activity in four states (remission, low, moderate, high) using κ statistics. The results of the study indicate that PTGL and GH ratings differ in their determinants. However they are individually not equivalent,and may be used interchangeably for calculating composite indices for RA activity assessment.
Study Additional 3
The objective of this study was to investigate agreement between the ESR- and CRP-based DAS-28 definitions. Data were obtained from registers of early (n = 520) and established RA (n = 364) patients. Agreement over disease activity levels (remission, low, moderate and high) at baseline and 6 months, and EULAR responder status at 6 months, were evaluated in the early cohort. Two alternative DAS-28(CRP) definitions, obtained through linear regression analyses at baseline in the early RA patients, were validated with 6-month data from both the cohorts. the results of the study indicate that The DAS-28(ESR) and DAS-28(CRP) definitions differ considerably in classifying RA patients as having moderate or high disease activity, with the ESR definition resulting in a higher proportion of high DAS-28 especially in women.