10.46. Disease Activity Score-28 (DAS28)

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Disease activity score for rheumatoid arthritis. The 28 refers to the number of joints in which disease activity is rated (bilaterally: shoulder, elbow, wrist, knee, 5 × MCP, 5 × PIP).

For each joint, “swollen?” and “tender?” are asked; there is a visual analogue rating scale (100 mm in length) for arthritis activity, plus an inflammatory marker. In the original DAS28 (sometimes termed the DAS28-ESR), this was ESR (erythrocyte sedimentation rate). An alternative is the CRP (C-reactive protein), in the DAS28-CRP.

• t28 = number of tender joints, range [0, 28].

• sw28 = number of swollen joints, range [0, 28].

• The CRP units are mg/L and in the range [0, 300].

• The ESR units are mm/hr and in the range [1, 300].

• The VAS (visual analogue scale) units are mm, range [0, 100]. Low is inactive arthritis; high is extremely active arthritis.

DAS28 score = 0.56 × √(t28) + 0.28 × √(sw28) + 0.70 × ln(ESR) + 0.014 × VAS

DAS28-CRP score = 0.56 × √(t28) + 0.28 × √(sw28) + 0.36 × ln(CRP + 1) + 0.014 × VAS + 0.96.

These are the “4-variable” DAS scales (tenderness, swelling, inflammatory marker, VAS). There are different 3-variables scales too, without the VAS, not implemented here.

10.46.1. Intellectual property rights

• Copyright © 1995, Prof. dr. Piet L.C.M. van Riel (as per https://eprovide.mapi-trust.org/instruments/disease-activity-score-c-reactive-protein#contact_and_conditions_of_use).

10.46.2. History

• Prevoo ML, van ‘t Hof MA, Kuper HH, van Leeuwen MA, van de Putte LB, van Riel PL (1995). Modified disease activity scores that include twenty-eight-joint counts. Development and validation in a prospective longitudinal study of patients with rheumatoid arthritis. Arthritis Rheum. 38: 44-8. https://www.ncbi.nlm.nih.gov/pubmed/7818570

  [Original version using ESR.]

• Fransen J, Welsing PMJ, de Keijzer RMH, van Riel PLCM (2003). Disease activity scores using C-reactive protein: CRP may replace ESR in the assessment of RA disease activity. Ann Rheum Dis 62(Suppl. 1): 151. https://www.researchgate.net/publication/291893932_Disease_activity_scores_using_C-reactive_protein_CRP_may_replace_ESR_in_the_assessment_of_RA_disease_activity. (That says 2004, but vol. 62 supplement 2 was in 2003 according to https://www.ncbi.nlm.nih.gov/pmc/journals/149/ so 2003 probably correct.)

  [DAS-28-CRP source, according to Hensor et al. 2010 as below.]

• Fleischmann RM, van der Heijde D, Gardiner PV, Szumski A, Marshall L, Bananis E (2017). DAS28-CRP and DAS28-ESR cut-offs for high disease activity in rheumatoid arthritis are not interchangeable. RMD Open 3: e000382. https://doi.org/10.1136/rmdopen-2016-000382. https://www.ncbi.nlm.nih.gov/pubmed/28255449.

  [Helpful review comparing DAS28-ESR and DAS28-CRP.]

• Hensor EM, Emery P, Bingham SJ, Conaghan PG; YEAR Consortium (2010). Discrepancies in categorizing rheumatoid arthritis patients by DAS-28(ESR) and DAS-28(CRP): can they be reduced? Rheumatology (Oxford) 49: 1521-9. https://doi.org/10.1093/rheumatology/keq117. https://www.ncbi.nlm.nih.gov/pubmed/20435650.

  [Useful history.]

10.46.3. Source

• https://eprovide.mapi-trust.org/instruments/disease-activity-score-c-reactive-protein#contact_and_conditions_of_use

• https://www.das28.nl/

  … the Excel file dasculators.xls (created 2003-01-13) provides the following rules:

  • Tender joint count range [0, 28].

  • Swollen joint count range [0, 28].

  • CRP integer only; CRP in range [1, 300] according to the warning when you enter invalid values, but actually [0, 300] accepted.

  • ESR integer only; ESR in range [1, 300].

  • VAS general health integer only; range [0, 100].

• DAS-ESR cutoffs as per:

  Anderson J, Caplan L, Yazdany J, Robbins ML, Neogi T, Michaud K, Saag KG, O’Dell JR, Kazi S (2012). Rheumatoid arthritis disease activity measures: American College of Rheumatology recommendations for use in clinical practice. Arthritis Care Res 64: 640-7. https://www.ncbi.nlm.nih.gov/pubmed/22473918; https://doi.org/10.1002/acr.21649; https://onlinelibrary.wiley.com/doi/full/10.1002/acr.21649.

• DAS-CRP cutoffs as per:

  Fleischmann RM, van der Heijde D, Gardiner PV, Szumski A, Marshall L, Bananis E (2017). DAS28-CRP and DAS28-ESR cut-offs for high disease activity in rheumatoid arthritis are not interchangeable. RMD Open 3: e000382. https://www.ncbi.nlm.nih.gov/pubmed/28255449; https://doi.org/10.1136/rmdopen-2016-000382; https://rmdopen.bmj.com/content/3/1/e000382.