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Rheumatoid arthritis
Original article
DAS28-CRP and DAS28-ESR cut-offs for high disease activity in rheumatoid arthritis are not interchangeable
  1. Roy M Fleischmann1,
  2. Désirée van der Heijde2,
  3. Philip V Gardiner3,
  4. Annette Szumski4,
  5. Lisa Marshall5 and
  6. Eustratios Bananis5
  1. 1University of Texas, Dallas, Texas, USA
  2. 2Leiden University Medical Center, Leiden, The Netherlands
  3. 3Western Health and Social Care Trust, Londonderry, UK
  4. 4inVentiv Health, Princeton, New Jersey, USA
  5. 5Pfizer, Collegeville, Pennsylvania, USA
  1. Correspondence to Dr Roy M Fleischmann; RFleischmann{at}arthdocs.com

Abstract

Background In most patients with rheumatoid arthritis (RA), Disease Activity Score 28-joint count C reactive protein (DAS28-CRP) is lower than DAS28 erythrocyte sedimentation rate (DAS28-ESR), suggesting that use of the DAS28-ESR cut-off to assess high disease activity (HDA) with DAS28-CRP may underestimate the number of patients with HDA. We determined the DAS28-CRP value corresponding to the validated DAS28-ESR cut-off for HDA.

Methods Baseline data were pooled from 2 clinical studies evaluating etanercept (ETN) plus methotrexate (MTX) or MTX in early RA; DAS28-CRP and DAS28-ESR were obtained, allowing the determination of the DAS28-CRP HDA value best corresponding to the DAS28-ESR cut-off of >5.1.

Results At baseline, as expected, fewer patients had HDA by DAS28-CRP than DAS28-ESR; DAS28-CRP>5.1 and DAS28-ESR>5.1 had only modest agreement (κ coefficients 0.45–0.54). Mean DAS28-CRP and DAS28-ESR were 5.7 and 6.2, respectively, in the ETN+MTX group (n=571), and 6.0 and 6.5 in the MTX group (n=262). A DAS28-CRP cut-off of 4.6 corresponded to a DAS28-ESR cut-off of 5.1.

Conclusions We have shown that a DAS28-CRP of 4.6 corresponds to 5.1 for DAS28-ESR. Since this is substantially lower than the DAS28-ESR cut-off of 5.1, using 5.1 as the cut-off for DAS28-CRP underestimates disease activity in RA.

Trial registration number NCT00195494; NCT00913458.

  • Rheumatoid Arthritis
  • Anti-TNF
  • DAS28

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

https://doi.org/10.1136/rmdopen-2016-000382

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    Footnotes

    • Funding The clinical trials included in this analysis were funded by Pfizer. Medical writing support was provided by Jennica Lewis of Engage Scientific Solutions and was funded by Pfizer.

    • Competing interests RMF was a principal investigator for clinical trials used in this analysis and has received consulting fees unrelated to the development of this article. DvdH has received consulting fees from Pfizer unrelated to the development of this article. AS is an employee of inVentiv Health and was contracted by Pfizer to provide statistical support for the development of this article. LM and EB are employees of Pfizer.

    • Ethics approval For the COMET and PRIZE trials, the final protocol, any amendments and informed consent documentation were reviewed and approved by the Institutional Review Board(s) and Independent Ethics Committee(s) at each of the investigational centres participating in the studies.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data sharing statement No additional data are available.