DAS28-CRP Calculator
Use this tool to estimate Disease Activity Score in 28 joints (DAS28) using C-reactive protein (CRP).
What is a DAS28 PCR calculator?
People often search for a DAS28 PCR calculator, but in rheumatology this is usually written as DAS28-CRP. It is a clinical score used in rheumatoid arthritis to summarize disease activity from four inputs: tender joint count, swollen joint count, CRP blood test, and patient global health score.
The result gives a single number that helps clinicians monitor inflammation over time and evaluate treatment response. It is most useful when tracked serially, not as a one-time standalone value.
How to interpret the score
The following cutoffs are commonly used in practice for DAS28 interpretation:
- < 2.6: Remission
- 2.6 to 3.2: Low disease activity
- > 3.2 to 5.1: Moderate disease activity
- > 5.1: High disease activity
Important: exact remission thresholds can vary by guideline and whether ESR- or CRP-based equations are used. Always apply local clinical protocol.
Input details and practical tips
1) Tender Joint Count (TJC28)
TJC28 reflects pain/tenderness in 28 standardized joints. Higher values increase the final score significantly, since the formula applies a square root transformation.
2) Swollen Joint Count (SJC28)
SJC28 captures clinically swollen joints in the same 28-joint set. Although weighted less than TJC in the formula, it still contributes meaningfully to activity classification.
3) CRP value
CRP is entered in mg/L and transformed using the natural log function in the equation (ln[CRP+1]). This reduces extreme influence from very high values while preserving inflammatory signal.
4) Global Health (GH)
GH is a patient-reported measure from 0 to 100. It adds patient perspective to the score, capturing pain, fatigue, and overall impact beyond joint counts alone.
Why this calculator is useful
- Quickly estimates disease activity in clinic or remote follow-up.
- Supports treat-to-target discussions in rheumatoid arthritis management.
- Helps compare current status with previous visits.
- Improves communication by translating multiple data points into one tracked metric.
Common mistakes to avoid
- Mixing CRP units (always verify mg/L for this equation).
- Entering values outside valid ranges (joint counts must be 0-28).
- Using the score alone without full clinical context.
- Confusing DAS28-ESR and DAS28-CRP thresholds and formulas.
Clinical disclaimer
This DAS28-CRP calculator is for educational and informational use only. It does not diagnose disease, replace professional judgment, or substitute for individualized medical care. Final decisions should be made by qualified healthcare professionals using complete clinical information.