Rheumatology
DAS28-ESR
Rheumatoid arthritis disease activity.
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Background
DAS28-ESR is a composite measure of disease activity in rheumatoid arthritis, combining four components into a single value: a tender joint count and a swollen joint count (each out of 28 specified joints), the erythrocyte sedimentation rate (ESR) and the patient's global assessment of health on a 0–100 visual analogue scale. The components are combined with a weighting formula that includes a natural logarithm of the ESR. The result quantifies how active the disease is at a point in time. It is central to the treat-to-target approach, in which therapy is adjusted to reach and maintain low disease activity or remission.
Interpreting the result
Conventional thresholds are: remission below 2.6, low activity 2.6 to 3.2, moderate activity above 3.2 up to 5.1, and high activity above 5.1. Repeated measurements track response to treatment, and a fall across these bands signals improvement. The aim of treatment is to reach remission or at least low activity and to escalate therapy when activity remains moderate or high. The score guides treatment intensity but is interpreted alongside imaging, function and the overall clinical picture.
Worked example
A patient has 6 tender and 4 swollen joints (of 28), an ESR of 40 mm/hr and a global health score of 60 on the visual analogue scale. Combined through the DAS28 formula, this gives a value above 5.1, indicating high disease activity and prompting consideration of treatment escalation.
Critical actions
ESR must be > 0 (uses a natural log). Patient global health is a 0–100 mm visual analogue scale.
Pearls / pitfalls
- The ESR must be greater than zero because the formula takes its natural logarithm; very low or missing ESR values distort the result.
- The patient global health item is a 0–100 mm visual analogue scale and contributes meaningfully to the total.
- ESR is influenced by age, sex, anaemia and infection, so a raised DAS28-ESR is not always due to joint inflammation.
- The 28-joint count omits the feet and ankles, so it can underestimate activity in patients with predominant lower-limb disease.
Evidence & validation
The 28-joint disease activity scores were developed by Prevoo and colleagues (Arthritis & Rheumatism, 1995) and are endorsed by EULAR and used in NICE guidance for assessing rheumatoid arthritis activity and response to therapy.
Frequently asked questions
What DAS28-ESR value means remission?
A DAS28-ESR below 2.6 conventionally indicates remission. Values of 2.6–3.2 represent low activity, above 3.2 up to 5.1 moderate activity, and above 5.1 high activity.
How is DAS28-ESR used in treat-to-target?
The score is measured repeatedly to track disease activity, and treatment is escalated when activity remains moderate or high, aiming to reach and sustain remission or low activity. A falling score across the bands indicates a response.
Why might the ESR-based version differ from the CRP-based one?
ESR and CRP are different inflammatory markers with different dynamics, so DAS28-ESR and DAS28-CRP can give slightly different values and thresholds. ESR is influenced by factors such as age, sex and anaemia, which can affect the result.
What if the ESR is zero or unavailable?
The formula uses the natural logarithm of the ESR, so the ESR must be greater than zero. A missing or zero value makes the calculation invalid, and a CRP-based version may be used instead.
Does the 28-joint count cover all affected joints?
No. It assesses 28 specified joints and excludes the feet and ankles, so disease confined to the lower limbs may be underestimated, and the score should be read alongside the full clinical assessment.
References
- Prevoo ML, van 't Hof MA, Kuper HH, et al. Modified disease activity scores that include twenty-eight-joint counts. Development and validation in a prospective longitudinal study of patients with rheumatoid arthritis. Arthritis Rheum. 1995;38(1):44–48.
- NICE NG100: Rheumatoid arthritis in adults: management. 2018.
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