Healthcare & Clinical Calculations
DAS28-ESR & DAS28-CRP Rheumatoid Arthritis Activity Calculator
Calculate EULAR 28-joint Disease Activity Scores DAS28-ESR and DAS28-CRP from Tender Joint Count (0–28), Swollen Joint Count (0–28), ESR (mm/h) or CRP (mg/L), and Patient Global VAS (0–100 mm).
Quantify EULAR treat-to-target rheumatoid arthritis remission (< 2.6) with SQRT & LN!
M. L. L. Prevoo and Piet van Riel (Arthritis & Rheumatism 1995) transformed modern rheumatology by weighting 28-joint Tender Joint Count (TJC28, twice the weight of swollen joints!), 28-joint Swollen Joint Count (SJC28), acute-phase inflammation, and Patient Global Health Visual Analog Scale (GH, 0–100 mm) into the continuous Disease Activity Score DAS28: DAS28-ESR = 0.56 * SQRT(TJC28) + 0.28 * SQRT(SJC28) + 0.70 * LN(ESR_mmh) + 0.014 * GH_mm, and its C-reactive protein counterpart DAS28-CRP = 0.56 * SQRT(TJC28) + 0.28 * SQRT(SJC28) + 0.36 * LN(CRP_mgL + 1) + 0.014 * GH_mm + 0.96!
Notice carefully that DAS28-CRP requires CRP in mg/L (NOT mg/dL—multiply mg/dL by 10!) inside LN(CRP_mgL + 1)! EULAR cutoffs classify DAS28-ESR < 2.6 as Remission, 2.6–3.2 as Low Disease Activity, > 3.2–5.1 as Moderate Disease Activity, and > 5.1 as High Disease Activity warranting bDMARD / tsDMARD escalation! For an active flare (TJC28 = 8, SJC28 = 5, ESR = 38 mm/h, CRP = 18 mg/L, GH = 55 mm), DAS28-ESR = 5.53 (High Activity > 5.1) and DAS28-CRP = 5.00!
| Rheumatoid Arthritis Joint & Lab State | DAS28-ESR Score | DAS28-CRP Score (CRP mg/L) | EULAR Activity Classification |
|---|---|---|---|
| Sustained Remission (TJC 0, SJC 0, ESR 8, GH 10) | 1.60 (< 2.6) | 1.89 | EULAR Clinical Remission (< 2.6) |
| Moderate Synovitis (TJC 3, SJC 2, ESR 22, GH 35) | 4.02 (3.2–5.1) | 3.66 | Moderate Activity — Optimize DMARD |
| Severe Flare (TJC 8, SJC 5, ESR 38, CRP 18, GH 55) | 5.53 (> 5.1) | 5.00 | High Activity — Escalate Biologic |
4-Variable EULAR DAS28-ESR Score
Evaluates 0.56 * SQRT(TJC28) + 0.28 * SQRT(SJC28) + 0.70 * LN(ESR) + 0.014 * GH across valid 0–28 joint counts and ESR >= 1 mm/h.
=IF(OR(B2 < 0, B2 > 28, B3 < 0, B3 > 28, B4 < 1, B5 < 0, B6 < 0, B6 > 100), "Invalid Joint / Lab Input", ROUND(0.56 * SQRT(B2) + 0.28 * SQRT(B3) + 0.7 * LN(B4) + 0.014 * B6, 2))4-Variable EULAR DAS28-CRP Score (CRP in mg/L)
Evaluates 0.56 * SQRT(TJC28) + 0.28 * SQRT(SJC28) + 0.36 * LN(CRP_mgL + 1) + 0.014 * GH + 0.96.
=IF(OR(B2 < 0, B2 > 28, B3 < 0, B3 > 28, B4 < 1, B5 < 0, B6 < 0, B6 > 100), "Invalid Joint / Lab Input", ROUND(0.56 * SQRT(B2) + 0.28 * SQRT(B3) + 0.36 * LN(B5 + 1) + 0.014 * B6 + 0.96, 2))Try the example
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