Rheumatology
DAS28-CRP
Rheumatoid arthritis activity (CRP version).
Education and reference only. Not a substitute for clinical judgement, local policy or product labelling. Always verify before clinical use. Values are calculated in your browser and never stored.
Background
DAS28-CRP is a composite measure of disease activity in rheumatoid arthritis (RA) that uses C-reactive protein (CRP) rather than the erythrocyte sedimentation rate. It combines four elements: a tender joint count and a swollen joint count each based on 28 defined joints, the CRP in mg/L, and the patient's global assessment of health on a 0–100 visual analogue scale. These are entered into a weighted formula to produce a single continuous activity score. The tool is used to grade activity and to track response to treatment in a treat-to-target approach.
Interpreting the result
The result is read against standard thresholds: below 2.6 indicates remission, 2.6–3.2 low disease activity, above 3.2 up to 5.1 moderate activity, and above 5.1 high disease activity. These bands guide treatment escalation and the assessment of treatment response over time. Because the score is continuous, the change between visits is often as informative as the absolute band.
Worked example
A patient has 5 tender and 3 swollen joints (of 28), a CRP of 20 mg/L and a global health score of 40: entering these into the DAS28-CRP formula gives a value of roughly 4.5, indicating moderate disease activity and supporting a review of therapy.
Critical actions
CRP in mg/L. Note DAS28-CRP runs slightly lower than DAS28-ESR; use the same version consistently when tracking a patient.
Pearls / pitfalls
- DAS28-CRP tends to run slightly lower than DAS28-ESR, so use the same version consistently when monitoring a patient.
- CRP must be entered in mg/L; mixing up units will distort the score.
- The 28-joint count excludes the feet and ankles, so it can underestimate activity in patients with predominant foot involvement.
- The patient global score is subjective and can be raised by non-inflammatory pain or low mood, inflating the result.
Evidence & validation
The DAS28 was developed from the original Disease Activity Score, and the CRP-based variant was validated by Wells and colleagues against the ESR version. It is widely used in rheumatology practice and clinical trials and is referenced in EULAR recommendations on RA management and outcome assessment.
Frequently asked questions
What DAS28-CRP score means remission?
A score below 2.6 is conventionally taken to indicate remission. However, some patients in this band still have residual active joints, so clinical assessment remains important.
Is DAS28-CRP interchangeable with DAS28-ESR?
Not exactly. The CRP version generally gives slightly lower values for the same patient, so the two are not directly interchangeable. Track a patient with one version consistently.
Why might the score overestimate activity?
The patient global health score is subjective and can be elevated by fibromyalgia, mechanical pain or low mood rather than inflammation. This can push the composite score higher than the true inflammatory burden.
Does the 28-joint count cover the whole body?
No. It assesses 28 specified joints and excludes the feet and ankles. Patients with predominant foot disease may have their activity underestimated.
References
- Wells G, Becker J-C, Teng J, et al. Validation of the 28-joint Disease Activity Score (DAS28) and EULAR response criteria based on CRP against disease progression in patients with rheumatoid arthritis. Ann Rheum Dis. 2009;68(6):954–960.
- Smolen JS, et al. EULAR recommendations for the management of rheumatoid arthritis. Ann Rheum Dis.
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