title: Erythrocyte sedimentation rate, C-reactive protein level, and serum amyloid a protein for patient selection and monitoring of anti-tumor necrosis factor treatment in ankylosing spondylitis.
abstract: OBJECTIVE
  To study the usefulness of erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and serum amyloid A (SAA) for response prediction and monitoring of anti-tumor necrosis factor (anti-TNF) treatment in ankylosing spondylitis (AS) patients.
  
  
  METHODS
  Patients were included consecutively before starting etanercept or infliximab treatment. ASsessment in Ankylosing Spondylitis (ASAS) response, defined as a 50% improvement or an absolute improvement of 2 points of the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI; 0-10 scale), was assessed at 3 months. Inflammatory markers and the BASDAI were collected at baseline and 1 and 3 months. Longitudinal data analysis was performed to compare associations between inflammatory markers and the BASDAI over time by calculating standardized betas. Predictive values of baseline levels of inflammatory markers for ASAS response were calculated.
  
  
  RESULTS
  In total, 155 patients were included, of whom, after 3 months of treatment, 70% in the etanercept cohort and 71% in the infliximab cohort responded. All markers, notably SAA, decreased significantly (P < 0.0001). Standardized betas were 0.49 for ESR, 0.43 for CRP, and 0.39 for SAA. Normal baseline levels of CRP and SAA were significantly associated with nonresponse. A combination of elevated CRP and SAA levels at baseline revealed the highest predictive value (81%) for ASAS response.
  
  
  CONCLUSIONS
  ESR, CRP, and SAA were significantly associated with the BASDAI over 3 months, and the association with ESR was the strongest. Elevated baseline CRP and SAA levels revealed the highest predictive value for response. Together, this study demonstrates that inflammatory markers, and notably CRP and SAA, may facilitate patient selection and monitoring of efficacy of anti-TNF treatment in AS, and could be added to response criteria.
authors.affiliation: VU University Medical Centre, Amsterdam, The Netherlands.
authors.forename: Mirjam K
authors.initials: MK
authors.lastname: de Vries
authors.forename: Izhar C
authors.initials: IC
authors.lastname: van Eijk
authors.forename: Irene E
authors.initials: IE
authors.lastname: van der Horst-Bruinsma
authors.forename: Mike J L
authors.initials: MJ
authors.lastname: Peters
authors.forename: Michael T
authors.initials: MT
authors.lastname: Nurmohamed
authors.forename: Ben A C
authors.initials: BA
authors.lastname: Dijkmans
authors.forename: Bouke P C
authors.initials: BP
authors.lastname: Hazenberg
authors.forename: Gerrit J
authors.initials: GJ
authors.lastname: Wolbink
mesh_terms: D000328:Adult; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D001323:Autoantibodies / Q000097:blood; D015415:Biomarkers / Q000097:blood*; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000378:metabolism; D016903:Drug Monitoring / Q000379:methods*; D000068800:Etanercept; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000627:therapeutic use; D000069285:Infliximab; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D018124:Receptors, Tumor Necrosis Factor / Q000627:therapeutic use; D000685:Serum Amyloid A Protein / Q000378:metabolism; D013167:Spondylitis, Ankylosing / Q000097:blood / Q000188:drug therapy* / Q000276:immunology*; D016896:Treatment Outcome; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D018501:Antirheumatic Agents; D001323:Autoantibodies; D015415:Biomarkers; D007074:Immunoglobulin G; D018124:Receptors, Tumor Necrosis Factor; D000685:Serum Amyloid A Protein; D014409:Tumor Necrosis Factor-alpha; D002097:C-Reactive Protein; D000069285:Infliximab; D000068800:Etanercept