Shaw on Measurement
“The only man who behaved sensibly was my tailor; he took my measure anew every time he saw me, whilst all the rest went on with their old measurements and expected them to fit me.”
Clinical Disease Activity Index(CDAI)（临床DAS评分）
Disease Activity Score (DAS):A continuous measure
DAS=0.54•(Tender 44)1/2 +0.06 •(Swollen 66)1/2 + 0.33 In(ESR)+ 0.007 (Global Health on VAS) （44个压痛关节、66个肿胀关节） Provides absolute indication of RA disease activity on a scale of 1 to 9 -DAS > 3.6 = high disease activity -DAS 2.4- 3.6 = moderate disease activity -DAS 1.6- 2.4= low disease activity -DAS < 1.6 = remission
DT Felson et al. Arthritis Rheum.1995;38(6):727-735
Continuous Measures of RA Disease Activity
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Disease Activity Score (DAS)
DAS28
Simplified Disease Activity Index(SDAI)（简化的DAS评分）
(ACR50 responders include ACR20 responders)
-ACR70 is ≥ 70% improvement
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(ACR70 responders include ACR20 and ACR50 responders)
Used to maximally discriminate effective treatment from placebo treatment in clinical trials Not directly applicable to clinical practice
Why Assess Joints?

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Primary site of RA disease activity Persistent synovitis results in
-Joint destruction -Disability
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Goal of treatment (remission) is absence of synovitis Tender & swollen joint counts are outcome upon which therapeutic decisions are based
类风湿关节炎活动度临床判断
Clinical Assessment of Rheumatoid Arthritis Disease Activity
(Partly quoted from Jonathan Kay, MD)
Content
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Why quantify RA disease activity? Composite disease activity indices Response criteria for clinical trials Patient-reported outcome measures Quantitatively-driven therapy for early RA Data collection tools
ACR response criteria:the traditional dichotomous benchmark •
Reported as %improvement, comparing disease activity at two discrete time points -ACR20 is ≥ 20% improvement -ACR50 is ≥ 50% improvement
-George Bernard Shaw
(1856-1950)
How to quantify RA disease activity
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Clinical composite indices -DAS / DAS28 -SDAS -CDAI • Patient-reported outcome measures • Imaging - Plain radiographs - Musculoskeletal ultrasound - MRI
DM van der Heijde et al. J Rheumatol 1993;20:579-81
DAS28:A simplified disease activity score
Simplified disease activity score using 28-joint count -Integrates measures of physical examination, acute phase response, and patient self-assessment DAS28=0.56•(Tender 28)1/2 +0.28 •(Swollen 28)1/2 + 0.70 In(ESR)+ 0.014 (Global Health on VAS) Provides absolute indication of RA disease activity on a scale of 0.49 to 9.07 -DAS28 > 5.1 =high disease activity -DAS28 3.2- 5.1= moderate disease activity -DAS28 2.6- 3.2=low disease activity -DAS28 <2.6 = remission