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Calprotectin (a major leucocyte protein) is strongly and independently correlated with joint inflammation and damage in rheumatoid arthritis
  1. Hilde Berner Hammer1,
  2. Sigrid Ødeg̊ard1,
  3. Magne K Fagerhol1,
  4. Robert Landewé3,
  5. Désirée van der Heijde1,
  6. Till Uhlig1,
  7. Petter Mowinckel1,
  8. Tore K Kvien1
  1. 1Department of Rheumatology, Diakonhjemmet Hospital, Oslo, Norway
  2. 2Blood Bank and Department of Immunology, Ullevål Hospital, Oslo, Norway
  3. 3Department of Rheumatology, University Hospital Maastricht, Maastricht, Netherlands
  1. Correspondence to:
    Dr Hilde Berner Hammer
    Department of Rheumatology, Diakonhjemmet Hospital, Box 23, Vinderen, N-0319 Oslo, Norway; h-hammer{at}diakonsyk.no

Abstract

Objective: Calprotectin is a major leucocyte protein, shown to correlate well with laboratory and clinical assessments in several inflammatory rheumatic diseases, and large concentrations of calprotectin have been found in synovial fluid from patients with rheumatoid arthritis (RA). The objective of the present study was to examine correlations between calprotectin and joint damage.

Methods: 145 patients with RA were analysed cross sectionally with laboratory (calprotectin, C reactive protein (CRP), and erythrocyte sedimentation rate (ESR)), clinical (28 joint counts (tender, swollen), physician global VAS, DAS28 and RA Articular Damage score (RAAD)), and radiographic (plain hand radiographs; modified Sharp’s method) measurements, on the same day.

Results: Calprotectin showed a highly significant correlation with measures of joint damage; modified Sharp score r = 0.43 (p<0.001) and RAAD r = 0.40 (p<0.001). The association with modified Sharp score and RAAD score was maintained after adjustment for CRP, ESR, rheumatoid factor, DAS28, sex, and age in a multiple regression analysis (p = 0.018 and p = 0.04, respectively), while neither CRP nor ESR showed any independent associations. Highly significant correlations (p<0.001) were also found between calprotectin and both laboratory and clinical markers of inflammation.

Conclusion: Calprotectin was found to significantly and independently explain the variation in the radiological and clinical assessments of joint damage. Longitudinal studies are required to examine whether calprotectin may predict the progression of joint damage in RA.

  • anti-CCP, anti-cyclic citrullinated peptide
  • CRP, C reactive protein
  • DMARDs, disease modifying antirheumatic drugs
  • ESR, erythrocyte sedimentation rate
  • JRA, juvenile rheumatoid arthritis
  • NSAIDs, non-steroidal anti-inflammatory drugs
  • RA, rheumatoid arthritis
  • RAAD score, RA Articular Damage score
  • VAS, visual analogue scale
  • calprotectin
  • rheumatoid arthritis
  • joint inflammation
  • joint damage
  • radiographs

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Footnotes

  • Published Online First 18 January 2007

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