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Front. Med. | doi: 10.3389/fmed.2018.00040

Common Evaluations of Disease Activity in Rheumatoid Arthritis Reach Discordant Classifications Across Different Populations

 Helena Canhao1, 2*, Fernando M. Martins3, José A. Melo Gomes4, Maria J. Santos5, 6,  Augusto Faustino4,  José António Costa7, Cornelia Allaart8, Emilia Gvozdenović8, Desirée van der Heijde8, Pedro Machado9,  Jaime C. Branco1, 10,  João E. Fonseca5, 11 and José A. Silva12
  • 1CEDOC, Universidade Nova de Lisboa, Portugal
  • 2Escola Nacional de Saúde Pública, Universidade Nova de Lisboa, Portugal
  • 3Sociedade Portuguesa de Reumatologia, Portugal
  • 4Instituto Português de Reumatologia, Portugal
  • 5Rheumatology Research Unit, Instituto de Medicina Molecular (IMM), Portugal
  • 6Rheumatology Department, Hospital Garcia de Orta, Portugal
  • 7Centro Hospitalar do Alto Minho, EPE., Portugal
  • 8Rheumatology Department, Leiden University Medical Center, Netherlands
  • 9Centre for Rheumatology Research & MRC Centre for Neuromuscular Diseases, University College London, United Kingdom
  • 10Rheumatology Department, Centro Hospitalar de Lisboa Ocidental, Portugal
  • 11Rheumatology Department, Hospital de Santa Maria, Portugal
  • 12Faculdade de Medicina, Universidade de Coimbra, Portugal

Objectives: The classification of disease activity states in Rheumatoid Arthritis (RA) can be achieved through disease activity indices, such as the Disease Activity Score in 28 joints erythrocyte sedimentation rate (DAS28-ESR), the Simplified Disease Activity Index (SDAI) and the Clinical Disease Activity Index (CDAI). Subjective measurements, such as patient reported outcomes have been incorporated into several of these indices alongside more objective assessments, such as increases in the ESR and C-reactive protein. Moreover, while they use similar criteria, different indices weight these criteria to different extents. Therefore, the classifications based on each evaluation may not always be the same. We aim to compare the performance of the three indices and their individual components in two different populations.

Methods: Data from Dutch and Portuguese adherent centers were extracted from the METEOR database, a multinational collaboration on RA. We included a total of 24,605 visits from Dutch centers (from 5,870 patients) and 20,120 visits from Portuguese centers (from 3,185 patients). We compared the disease activity states as evaluated by the DAS28-ESR, CDAI, and SDAI across the two populations. In addition, we analyzed the individual components of each evaluation, including their respective contributions to the outcome, in each population.

Results: We found significant differences in the disease activity states classified with the DAS28-ESR between the two populations. SDAI and CDAI had more congruous results. While the proportion of visits to Dutch and Portuguese centers that were classified as “in remission” was very similar between the CDAI and SDAI, the DAS28-ESR gave discordant results. Dutch patients had lower ESRs, which is more heavily weighted in the DAS28-ESR. In addition, even though the mean physicians’ global assessment values did not vary significantly for Dutch vs Portuguese physicians, we found that doctors at Portuguese centers overall scored the physician’s global assessment lower than Dutch physicians for patient visits classified by disease activity state.

Conclusions: While the CDAI and SDAI assigned disease activity states that were largely similar, the DAS28-ESR was often discordant across the two populations. Moreover, we found that physicians, more than patients, evaluated disease activity differently among the Portuguese and Dutch populations.

Keywords: Rheumatoid arthritis, disease activity, Patient Reported Outcomes, Physicians’ perspective, acute phase reactants, meteor, DAS28-ESR

Received: 20 Sep 2017; Accepted: 05 Feb 2018.

Edited by:

Ying Ying Leung, Duke Medical School, National University of Singapore, Singapore

Reviewed by:

Peter Cheung, National University Health System, Singapore
Niti Goel, QuintilesIMS (United Kingdom), United Kingdom  

Copyright: © 2018 Canhao, Martins, Melo Gomes, Santos, Faustino, Costa, Allaart, Gvozdenović, van der Heijde, Machado, Branco, Fonseca and Silva. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: MD, PhD. Helena Canhao, Universidade Nova de Lisboa, CEDOC, Lisbon, Portugal,