title: Clinical relevance and inter-test reliability of anti-infliximab antibodies and infliximab trough levels in patients with inflammatory bowel disease.
abstract: BACKGROUND
  Treatment with infliximab is a common option for inflammatory bowel disease (IBD) patients. Therapeutic drug monitoring could improve treatment management.
  
  
  OBJECTIVE
  To test inter-test reliability of two commercially available diagnostic kits for infliximab trough levels and infliximab antibodies, and their association with treatment outcomes.
  
  
  METHODS
  86 IBD outpatients on infliximab maintenance treatment were enrolled in a prospective cross-sectional study, 115 samples were available for inter-test reliability.
  
  
  RESULTS
  Inter-test agreement was good both for trough levels (concordance correlation coefficient 0.78, weighted κ 0.60, Sperman's ρ 0.937) and for infliximab antibodies (weighted κ 0.79) measurement, when comparing Promonitor and ImmunDiagnostik kits. According to manufacturers' cut-off values, trough levels were classified as undetectable (17%), low (21%) or in range (63%). The only significant associations were: mucosal healing (p=0.026; OR 6.50), infliximab antibody status (p=0.0015; OR 0.031) and adverse events (p=0.009; OR 0.115). Higher trough levels were observed among patients on concomitant steroid/immunosuppressive therapy and among patients with dose-intensification. Infliximab antibodies were significantly associated to treatment-related adverse events (p=0.0003, OR 30.42), and to lower trough levels, but not to other clinical variables.
  
  
  CONCLUSIONS
  The two tests performed equally well. Infliximab antibodies were associated to adverse events, while trough levels were not associated to treatment outcomes.
authors.affiliation: Laboratory Unit, AO Ordine Mauriziano, Torino, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Guiotto
authors.affiliation: Gastroenterology Unit, AO Ordine Mauriziano, Torino, Italy. Electronic address: mdaperno@teletu.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Daperno
authors.affiliation: Gastroenterology Unit, AO Ordine Mauriziano, Torino, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Frigerio
authors.affiliation: Laboratory Unit, AO Ordine Mauriziano, Torino, Italy.
authors.forename: Margherita
authors.initials: M
authors.lastname: Vizzini
authors.affiliation: Laboratory Unit, AO Ordine Mauriziano, Torino, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Cerruti
authors.affiliation: Gastroenterology Unit, AO Ordine Mauriziano, Torino, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Ercole
authors.affiliation: Gastroenterology Unit, AO Ordine Mauriziano, Torino, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Cosimato
authors.affiliation: Gastroenterology Unit, AO Ordine Mauriziano, Torino, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Lavagna
authors.affiliation: Laboratory Unit, AO Ordine Mauriziano, Torino, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Germano
authors.affiliation: Laboratory Unit, AO Ordine Mauriziano, Torino, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Migliardi
authors.affiliation: Gastroenterology Unit, AO Ordine Mauriziano, Torino, Italy.
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Rocca
mesh_terms: D000906:Antibodies / Q000097:blood / Q000276:immunology*; D003430:Cross-Sectional Studies; D016903:Drug Monitoring; D005260:Female; D005765:Gastrointestinal Agents / Q000627:therapeutic use*; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000188:drug therapy*; D000069285:Infliximab / Q000097:blood / Q000276:immunology*; D008297:Male; D011446:Prospective Studies; D015203:Reproducibility of Results; D016896:Treatment Outcome
chemical_list: D000906:Antibodies; D005765:Gastrointestinal Agents; D000069285:Infliximab
keywords: Inflammatory bowel disease; Infliximab; Therapeutic drug monitoring