Das28 Score Calculator
Calculate Disease Activity Score 28 for rheumatoid arthritis assessment. Enter values for instant results with step-by-step formulas.
Formula
DAS28-ESR = 0.56*sqrt(TJC) + 0.28*sqrt(SJC) + 0.70*ln(ESR) + 0.014*GH
TJC = tender joint count (0-28), SJC = swollen joint count (0-28), ESR = erythrocyte sedimentation rate (mm/hr), GH = patient global health assessment (0-100 VAS). For DAS28-CRP: 0.56*sqrt(TJC) + 0.28*sqrt(SJC) + 0.36*ln(CRP+1) + 0.014*GH + 0.96. Remission < 2.6, Low < 3.2, Moderate 3.2-5.1, High > 5.1.
Worked Examples
Example 1: Moderate RA Activity on Current DMARDs
Problem: A patient on methotrexate has 6 tender joints, 4 swollen joints, ESR of 35 mm/hr, and rates their global assessment at 55/100.
Solution: Using DAS28-ESR formula:\nDAS28 = 0.56 x sqrt(6) + 0.28 x sqrt(4) + 0.70 x ln(35) + 0.014 x 55\nDAS28 = 0.56 x 2.449 + 0.28 x 2.0 + 0.70 x 3.555 + 0.77\nDAS28 = 1.371 + 0.560 + 2.489 + 0.770\nDAS28 = 5.19
Result: DAS28-ESR: 5.19 | High Disease Activity | Consider adding biologic DMARD or switching therapy
Example 2: Patient Approaching Remission
Problem: After switching to a TNF inhibitor, a patient has 1 tender joint, 0 swollen joints, ESR of 8 mm/hr, and patient global of 15/100.
Solution: Using DAS28-ESR formula:\nDAS28 = 0.56 x sqrt(1) + 0.28 x sqrt(0) + 0.70 x ln(8) + 0.014 x 15\nDAS28 = 0.56 x 1.0 + 0.28 x 0 + 0.70 x 2.079 + 0.21\nDAS28 = 0.560 + 0 + 1.455 + 0.210\nDAS28 = 2.23
Result: DAS28-ESR: 2.23 | Remission (< 2.6) | Continue current treatment, monitor every 3-6 months
Frequently Asked Questions
What is the DAS28 score and why is it used?
The Disease Activity Score 28 (DAS28) is a validated composite measure used to quantify disease activity in rheumatoid arthritis (RA). It was developed by the European League Against Rheumatism (EULAR) and combines four variables: tender joint count (out of 28 joints), swollen joint count (out of 28 joints), an acute phase reactant (ESR or CRP), and a patient global assessment of disease activity on a visual analog scale. The DAS28 produces a single numerical value that categorizes disease activity into remission, low, moderate, or high. It is widely used in clinical practice for treatment decisions, in clinical trials as a primary outcome measure, and in treat-to-target strategies.
Which 28 joints are assessed in the DAS28?
The DAS28 evaluates 28 specific joints bilaterally for tenderness and swelling. These include the proximal interphalangeal joints (10 joints, 5 per hand), metacarpophalangeal joints (10 joints, 5 per hand), wrists (2 joints), elbows (2 joints), shoulders (2 joints), and knees (2 joints). Notably, the DAS28 does not include the feet, ankles, hips, or temporomandibular joints, which is a recognized limitation since these joints are commonly affected in rheumatoid arthritis. The hips are excluded because they are difficult to assess clinically for swelling. The feet and ankles are omitted for practical reasons related to the original validation studies, though some clinicians supplement the DAS28 with foot examination.
What is the difference between DAS28-ESR and DAS28-CRP?
DAS28-ESR and DAS28-CRP use different acute phase reactants and have slightly different formulas. DAS28-ESR uses erythrocyte sedimentation rate and the formula is 0.56 times the square root of tender joint count plus 0.28 times the square root of swollen joint count plus 0.70 times the natural log of ESR plus 0.014 times the patient global assessment. DAS28-CRP replaces ESR with C-reactive protein and uses adjusted coefficients. The two versions are not interchangeable as DAS28-CRP tends to give slightly lower scores than DAS28-ESR. The same version should be used consistently for longitudinal monitoring of individual patients. DAS28-CRP may be preferred in patients where ESR is unreliable.
What DAS28 thresholds define disease activity levels?
The DAS28 score uses well-established thresholds to categorize rheumatoid arthritis disease activity into four levels. Remission is defined as a DAS28 score below 2.6, indicating minimal or absent disease activity and the ultimate treatment goal. Low disease activity is a score between 2.6 and 3.2, representing an acceptable therapeutic target when remission is not achievable. Moderate disease activity encompasses scores from 3.2 to 5.1, indicating the need for treatment adjustment. High disease activity is defined as a score above 5.1, signaling that aggressive treatment escalation is warranted. These thresholds were validated in the original DAS28-ESR studies and are widely accepted in clinical guidelines.
What is the EULAR response criteria using DAS28?
The EULAR response criteria use both the current DAS28 score and the change in DAS28 from baseline to classify treatment response. A good response requires both a DAS28 improvement greater than 1.2 AND a current DAS28 of 3.2 or less. A moderate response is defined as either a DAS28 improvement of 0.6 to 1.2 with a current DAS28 of 5.1 or less, OR an improvement greater than 1.2 with a current DAS28 above 3.2. No response means a DAS28 improvement of less than 0.6, OR an improvement of 0.6 to 1.2 with a current DAS28 above 5.1. These criteria provide a standardized framework for evaluating treatment effectiveness in both clinical practice and research trials.
How often should DAS28 be measured in clinical practice?
The frequency of DAS28 measurement depends on the current disease activity level and treatment phase. During active disease or after a treatment change, DAS28 should be assessed every 1 to 3 months to evaluate treatment response and guide adjustments according to treat-to-target principles. Once a patient achieves remission or low disease activity on a stable treatment regimen, monitoring intervals can be extended to every 3 to 6 months. The ACR and EULAR guidelines recommend a treat-to-target approach where therapy is adjusted every 3 months until the target of remission or low disease activity is achieved. Consistent measurement intervals help track trends and enable meaningful comparison of scores over time.