title: Serum calprotectin (S100A8/9): an independent predictor of ultrasound synovitis in patients with rheumatoid arthritis.
abstract: BACKGROUND
  Calprotectin, a heterodimeric complex of S100A8/9 (MRP8/14), has been proposed as an important serum biomarker that reflects disease activity and structural joint damage in rheumatoid arthritis (RA). The objective of this cross-sectional study was to test the hypothesis that calprotectin is associated with clinical and ultrasound-determined disease activity in patients with RA.
  
  
  METHODS
  A total of 37 patients with RA (including 24 females, a mean disease duration of 20 months) underwent a clinical examination and 7-joint ultrasound score (German US-7) of the clinically dominant hand and foot to assess synovitis by grey-scale (GS) and synovial vascularity by power Doppler (PD) ultrasound using semiquantitative 0-3 grading. The levels of serum calprotectin and C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were determined at the time of the ultrasound assessment. We analysed the relationship between serum calprotectin level, traditional inflammatory markers, and ultrasound-determined synovitis.
  
  
  RESULTS
  The levels of serum calprotectin were significantly correlated with swollen joint count (r = 0.465, p < 0.005), DAS28-ESR (r = 0.430, p < 0.01), ESR (r = 0.370, p < 0.05) and, in particular, CRP (r = 0.629, p < 0.001). Calprotectin was significantly associated with GS (r = 0.359, p < 0.05) and PD synovitis scores (r = 0.497, p < 0.005). Using multivariate regression analysis, calprotectin, adjusted for age and sex, was a better predictor of PD synovitis score (R(2) = 0.765, p < 0.001) than CRP (R(2) = 0.496, p < 0.001).
  
  
  CONCLUSIONS
  The serum levels of calprotectin are significantly associated with clinical, laboratory and ultrasound assessments of RA disease activity. These results suggest that calprotectin might be superior to CRP for monitoring ultrasound-determined synovial inflammation in RA patients.
authors.affiliation: Institute of Rheumatology, Na Slupi 4, 128 05, Prague 2, Czech Republic.|Department of Rheumatology, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
authors.forename: Jana
authors.initials: J
authors.lastname: Hurnakova
authors.affiliation: Institute of Rheumatology, Na Slupi 4, 128 05, Prague 2, Czech Republic.|Department of Rheumatology, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
authors.forename: Jakub
authors.initials: J
authors.lastname: Zavada
authors.affiliation: Institute of Rheumatology, Na Slupi 4, 128 05, Prague 2, Czech Republic.|Department of Rheumatology, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
authors.forename: Petra
authors.initials: P
authors.lastname: Hanova
authors.affiliation: Institute of Rheumatology, Na Slupi 4, 128 05, Prague 2, Czech Republic.|Department of Rheumatology, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
authors.forename: Hana
authors.initials: H
authors.lastname: Hulejova
authors.affiliation: Institute of Rheumatology, Na Slupi 4, 128 05, Prague 2, Czech Republic.|Department of Rheumatology, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Klein
authors.affiliation: Institute of Rheumatology, Na Slupi 4, 128 05, Prague 2, Czech Republic.|Department of Rheumatology, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
authors.forename: Herman
authors.initials: H
authors.lastname: Mann
authors.affiliation: Institute of Rheumatology, Na Slupi 4, 128 05, Prague 2, Czech Republic.|Department of Rheumatology, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
authors.forename: Olga
authors.initials: O
authors.lastname: Sleglova
authors.affiliation: Institute of Rheumatology, Na Slupi 4, 128 05, Prague 2, Czech Republic.|Department of Rheumatology, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
authors.forename: Marta
authors.initials: M
authors.lastname: Olejarova
authors.affiliation: Institute of Rheumatology, Na Slupi 4, 128 05, Prague 2, Czech Republic.|Department of Rheumatology, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
authors.forename: Sarka
authors.initials: S
authors.lastname: Forejtova
authors.affiliation: Institute of Rheumatology, Na Slupi 4, 128 05, Prague 2, Czech Republic.|Department of Rheumatology, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
authors.forename: Olga
authors.initials: O
authors.lastname: Ruzickova
authors.affiliation: Institute of biophysics and informatics, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Komarc
authors.affiliation: Institute of Rheumatology, Na Slupi 4, 128 05, Prague 2, Czech Republic.|Department of Rheumatology, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
authors.forename: Jiri
authors.initials: J
authors.lastname: Vencovsky
authors.affiliation: Institute of Rheumatology, Na Slupi 4, 128 05, Prague 2, Czech Republic.|Department of Rheumatology, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
authors.forename: Karel
authors.initials: K
authors.lastname: Pavelka
authors.affiliation: Institute of Rheumatology, Na Slupi 4, 128 05, Prague 2, Czech Republic. senolt@revma.cz.|Department of Rheumatology, 1st Faculty of Medicine, Charles University, Prague, Czech Republic. senolt@revma.cz.
authors.forename: Ladislav
authors.initials: L
authors.lastname: Senolt
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000175:diagnosis / Q000000981:diagnostic imaging; D015415:Biomarkers / Q000097:blood*; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000378:metabolism; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D039841:Leukocyte L1 Antigen Complex / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D013585:Synovitis / Q000097:blood* / Q000175:diagnosis / Q000000981:diagnostic imaging; D018608:Ultrasonography, Doppler / Q000379:methods
chemical_list: D015415:Biomarkers; D039841:Leukocyte L1 Antigen Complex; D002097:C-Reactive Protein