Calculator Guides
DAS28: Rheumatoid Arthritis Disease Activity Score Guide
The Disease Activity Score in 28 Joints (DAS28) quantifies RA disease activity using tender joint count, swollen joint count, patient global health, and ESR or CRP. DAS28 <2.6 = remission; 2.6–3.2 = low disease activity; >5.1 = high. It is the cornerstone of treat-to-target strategy.
TL;DR: The Disease Activity Score in 28 Joints (DAS28) quantifies RA disease activity using tender joint count, swollen joint count, patient global health, and ESR or CRP. DAS28 <2.6 = remission; 2.6–3.2 = low disease activity; 3.2–5.1 = moderate; >5.1 = high. It is the cornerstone of treat-to-target (T2T) strategy — the approach that transformed RA outcomes over the past two decades. DAS28 is a monitoring tool: calculate it at every clinical encounter, adjust therapy when the target isn't met.
DAS28 Calculation
DAS28-ESR Formula
DAS28-ESR = 0.56 × √(TJC28) + 0.28 × √(SJC28) + 0.70 × ln(ESR) + 0.014 × PGA
DAS28-CRP Formula
DAS28-CRP = 0.56 × √(TJC28) + 0.28 × √(SJC28) + 0.36 × ln(CRP + 1) + 0.014 × PGA + 0.96
Score Interpretation
| DAS28 Score | Disease Activity | Clinical Action |
|---|---|---|
| <2.6 | Remission | Maintain current therapy; consider cautious tapering |
| 2.6–3.2 | Low disease activity | Acceptable target if remission unachievable |
| 3.2–5.1 | Moderate | Escalate therapy |
| >5.1 | High | Urgent escalation; consider biologic initiation |
Treat-to-Target Strategy
The T2T approach: measure DAS28 regularly (every 1–3 months in active disease); if not at target (remission or LDA), escalate treatment; reassess at next visit.
DAS28-ESR vs DAS28-CRP
DAS28-CRP tends to give slightly lower scores than DAS28-ESR. CRP responds faster to inflammation changes. ESR is elevated by anemia, age, and female sex independent of RA activity.
Evidence and Guidelines
- Geng Y, et al. Clin Rheumatol. 2020;40(1):113–121. PMID: 32514681.
- Møller-Bisgaard S, et al. RMD Open. 2024;10(1). PMID: 38490697.
- van der Heijde DM, et al. Ann Rheum Dis. 1990;49(11):916–920. PMID: 2256738.
- Smolen JS, et al. EULAR recommendations 2022. Ann Rheum Dis. 2023;82(1):3–18. PMID: 36220332.
Frequently Asked Questions
Q: Which 28 joints are included in DAS28? Bilateral: shoulders, elbows, wrists, MCP 1–5, PIP 2–5, and knees. Hip, ankle, and foot joints are NOT included.
Q: Should DAS28 guide biologic prescription? In most healthcare systems, DAS28 >5.1 after failure of ≥2 conventional DMARDs is the threshold for biologic eligibility.
References
- Geng Y, et al. Clin Rheumatol. 2020;40(1):113–121.
- Møller-Bisgaard S, et al. RMD Open. 2024;10(1).
- van der Heijde DM, et al. Ann Rheum Dis. 1990;49(11):916–920.
- Smolen JS, et al. Ann Rheum Dis. 2023;82(1):3–18.