Skip to main content

The Effect Size of Fibromyalgia on PG-VAS in Rheumatoid Arthritis Patients. Adjustment Proposal in DAS28-ESR: Letter to the Editor regarding Challa, D.N.V., Crowson, C.S. & Davis, J.M. Rheumatol Ther (2017) 4: 201. doi:10.1007/s40744-017-0063-5

Dear Editor,

With great interest we read the article “The Patient Global Assessment of Disease Activity in Rheumatoid Arthritis: Identification of Underlying Latent Factors”, by Challa et al [1]. The authors conducted an analytic, observational study in 70 rheumatoid arthritis (RA) patients. Data were evaluated using exploratory factor analysis to determine to what extent each factor influences the discordant Patient Global Assessment (PGA) of disease activity. Interestingly, we observed in the multivariate analysis the persistent influence of fibromyalgia syndrome in the PGA. The disease activity score in 28 joints with erythrocyte sedimentation rate (DAS-ESR) is a method used to monitor disease activity in RA and is calculated using PGA.

We hypothesized that every non-RA musculoskeletal disorder could impact the PGA [25], as the patient no longer differentiates the pain source when various disorders coexist. We therefore, conducted an observational, descriptive cross-sectional study in 395 RA patients at a university hospital and analyzed the effect of fibromyalgia, knee osteoarthritis, and presence of tendinopathy (any) on the status of RA activity. Evaluation of the Health Assessment Questionnaire (HAQ) and Patient’s Global assessment Visual Analogue Scale (PG-VAS) was included. We considered a VAS >40 to have clinical significance. We analyzed 395 patients, 390 (91.1%) women, with a mean age of 51.1 (SD 12.7). Table 1 shows the clinical and activity characteristics of the RA patients with and without fibromyalgia. We found in the bivariate analysis that the presence of a VAS >40 was associated with a DAS28-ESR greater than 2.6 (OR 12.47, 5.2–29 95% CI, p = 0.001). Fibromyalgia was a predictor of PG-VAS >40 (OR 3.49, 1.72–7.08 95% CI, p = 0.0001). The other variables analyzed in the study did not have any influence on the DAS28-ESR in RA patients. As with the study by Challa et al., we observed an additive effect of fibromyalgia in the PG-VAS and therefore in the DAS28-ESR in patients with RA. The effect size of fibromyalgia diagnosis on the DAS28 was 27%. We propose to adjust the DAS28 when the PG-VAS is above 40 by multiplying by 0.73 to consider the effect of fibromyalgia in the evaluation. We believe this issue could be important in order to avoid overtreatment.

Table 1 Clinical, activity, and function characteristics of RA patients

References

  1. Challa DNV, Crowson CS, Davis JM. Rheumatol Ther. 2017;4:201. doi:10.1007/s40744-017-0063-5.

    Article  PubMed  PubMed Central  Google Scholar 

  2. Inanc N, Yilmaz-Oner S, Can M, Sokka T, Direskeneli H. The role of depression, anxiety, fatigue, and fibromyalgia on the evaluation of the remission status in patients with rheumatoid arthritis. J Rheumatol. 2014;41(9):1755–60. doi:10.3899/jrheum.131171.

    Article  PubMed  Google Scholar 

  3. Roig Vilaseca D, Hoces Otero C. Effect of the coexistence of fibromyalgia in the DAS28 index in women with rheumatoid arthritis. Reumatol Clin. 2008;4(3):96–9. doi:10.1016/S1699-258X(08)71811-4.

    Article  PubMed  Google Scholar 

  4. Ton E, Bakker MF, Verstappen SM, Ter Borg EJ, Albada-Kuipers IA, Schenk Y, Veen MJ, Bijlsma JW, Jacobs JW, Utrecht Rheumatoid Arthritis Cohort Study Group. Look beyond the disease activity score of 28 joints (DAS28): tender points influence the DAS28 in patients with rheumatoid arthritis. J Rheumatol. 2012;39(1):22–7. doi:10.3899/jrheum.110072.

    Article  PubMed  Google Scholar 

  5. Andersson ML, Svensson B, Bergman S. Chronic widespread pain in patients with rheumatoid arthritis and the relation between pain and disease activity measures over the first 5 years. J Rheumatol. 2013;40(12):1977–85. doi:10.3899/jrheum.130493.

    Article  PubMed  Google Scholar 

Download references

Acknowledgements

No funding or sponsorship was received for this study or publication of this article. All named authors meet the International Committee of Medical Journal Editors (ICMJE) criteria for authorship for this manuscript, take responsibility for the integrity of the work as a whole, and have given final approval for the version to be published.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to David Vega-Morales.

Ethics declarations

This article is based on previously conducted studies and does not involve any new studies of human or animal subjects.

Disclosures.

David Vega-Morales, Luis Ivan Lozano-Plata, and Jorge Antonio Esquivel-Valerio have nothing to disclose.

Open Access

This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), which permits any noncommercial use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Additional information

Enhanced content

To view enhanced content for this article go to http://www.medengine.com/Redeem/AC98F060497CDE96.

This letter refers to the original article available at doi:10.1007/s40744-017-0063-5.

Rights and permissions

This article is published under an open access license. Please check the 'Copyright Information' section either on this page or in the PDF for details of this license and what re-use is permitted. If your intended use exceeds what is permitted by the license or if you are unable to locate the licence and re-use information, please contact the Rights and Permissions team.

About this article

Verify currency and authenticity via CrossMark

Cite this article

Vega-Morales, D., Lozano-Plata, L.I. & Esquivel-Valerio, J.A. The Effect Size of Fibromyalgia on PG-VAS in Rheumatoid Arthritis Patients. Adjustment Proposal in DAS28-ESR: Letter to the Editor regarding Challa, D.N.V., Crowson, C.S. & Davis, J.M. Rheumatol Ther (2017) 4: 201. doi:10.1007/s40744-017-0063-5. Rheumatol Ther 4, 515–517 (2017). https://doi.org/10.1007/s40744-017-0067-1

Download citation

  • Received:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s40744-017-0067-1

Keywords

  • Fibromyalgia
  • Rheumatoid arthritis