Rheumatoid Arthritis

Disease Activity Measures

Introduction

Measuring Disease Activity in RA

Disease severity must be regularly quantified to implement a T2T strategy, but many RA disease activity measures exist, with varying performance.1

The ACR recommends the following 5 disease activity measures based on their feasibility for regular use in clinical practice, psychometric properties, and classification of numeric scores into at least 3 disease states.1

Measures

RA disease activity measures

Measure

CDAI1,2

Components

Score

Low DA: >2.8 to 10

Moderate DA: >10 to 22

High DA: >22

Attributes

  • Good hypotheses testing and responsiveness
  • Generally reliable and structurally valid
  • No lab testing required
  • Correlates with ACR response, DAS28, joint damage, and HAQ

Measure

SDAI1,2

Components

Score

Low DA: >3.3 to ≤11.0

Moderate DA: >11.0 to ≤26

High DA: >26

Attributes

  • Good hypotheses testing and responsiveness
  • Generally reliable
  • Requires lab testing
  • Correlates with ACR response, DAS28, joint damage, and HAQ

Measure

DAS28-ESR/CRP1,3

Components

Score

Low DA: 2.6 to <3.2

Moderate DA: 3.2 to ≤5.1

High DA: >5.1

Attributes

  • Good hypotheses testing and responsiveness
  • Generally reliable, structurally valid, and internally consistent
  • Moderate measurement error and less stringent definition of remission than CDAI and SDAI
  • Requires lab testing
  • In early RA (disease duration <5 years), patients achieving remission (DAS28 <2.6) have better function, QoL, and structural outcomes than patients with low DA

Measure

RAPID31,4,5

Components

Score

Low DA: 4 to 6

Moderate DA: 7 to 12

High DA: ≥13

Attributes

  • Good hypotheses testing, content validity, and responsiveness
  • Easy to incorporate in clinic because patient-driven, not needing physician assessments
  • Calculated in just 5-10 seconds
  • Significantly correlated with CDAI and DAS28

Measure

PAS-II1,4

Components

Score

Low DA: >0.26 to 3.70

Moderate DA: 3.71 to <8.0

High DA: ≥8.0

Attributes

  • Easy to incorporate in clinic because patient-driven, not needing physician assessments
  • Did not meet minimum standard for regular use due to inadequate psychometrics*
  • Uses HAQ-II, which is shorter than HAQ

Related

Patient-Reported Outcomes

Learn more about patient-reported outcomes

About Functional Status

Discover more about functional status measures

Discover our product information for rheumatoid arthritis

ACR, American College of Rheumatologists; CDAI, Clinical Disease Activity Index; CRP, C-reactive protein; DA, disease activity; DAS28, Disease Activity Score 28 Joints; DAS28-ESR/CRP, Disease Activity Score 28 Joints with Erythrocyte Sedimentation Rate or C-Reactive Protein; ESR, erythrocyte sedimentation rate; HAQ, Health Assessment Questionnaire; HAQ-II, Health Assessment Questionnaire II; MDHAQ, Multidimensional Health Assessment Questionnaire; PAS-II, Patient Activity Scale-II; PrGA, provider global assessment; PtGA, patient global assessment; QoL, quality of life; RA, rheumatoid arthritis; RAPID3, Routine Assessment of Patient Index Data 3; SDAI, Simplified Disease Activity Index; SJC, swollen joint count; T2T, treat to target; TJC, tender joint count; VAS, visual analogue scale.

* PAS-II was nevertheless recommended due to its feasibility, current use, inclusion in prior ACR recommendations, and alignment with the concurrent functional status assessment project.1


REFERENCES

1. England BR, Tiong BK, Bergman MJ, et al. Arthritis Care Res (Hoboken). 2019;71(12):1540-1555. 2. Smolen JS, Aletaha D. Clin Exp Rheumatol. 2014;32(5 Suppl 85):S75-S79. 3. Nikiphorou E, Norton SJ, Carpenter L, et al. Rheumatology (Oxford). 2020;59(6):1272-1280. 4. Anderson J, Caplan L, Yazdany J, et al. Arthritis Care Res (Hoboken). 2012;64(5):640-647. 5. Pincus T, Yazici Y, Bergman MJ. Rheum Dis Clin North Am. 2009;35(4):773-778.