title: Thiopurine monitoring in children with inflammatory bowel disease: a systematic review.
abstract: OBJECTIVE
  The aim was to systematically review the evidence on the clinical usefulness of thiopurine metabolite and white blood count (WBC) monitoring in the assessment of clinical outcomes in children with inflammatory bowel disease (IBD).
  
  
  METHODS
  Medline, Embase, Cochrane Central Register of controlled trials and http://www.clinicaltrials.gov were screened in adherence to the PRISMA statement by two independent reviewers for identification of eligible studies. Eligible studies were randomized controlled trials (RCTs), cohort studies and large case series of children with inflammatory bowel disease (IBD) (<18 years) who underwent monitoring of thiopurine metabolites and/or WBC.
  
  
  RESULTS
  Fifteen papers were identified (n = 1026). None of the eligible studies were RCTs. High 6-thioguanine nucleotide (6TGN) concentrations were not consistently associated with leucopenia. Leucopenia was not associated with achievement of clinical remission. A positive but not consistent correlation between 6TGN and clinical remission was reported. Haematological toxicity could not be reliably assessed with 6TGN measurements only. A number of studies supported the use of high 6-methylmercaptopurine ribonucleotides (6MMPR) as an indicator of hepatotoxicity. Low thiopurine metabolite concentration may be indicative of non-compliance.
  
  
  CONCLUSIONS
  Thiopurine metabolite testing does not safely predict clinical outcome, but may facilitate toxicity surveillance and treatment optimization in poor responders. Current evidence favours the combination of thiopurine metabolite/WBC monitoring and clinic follow-up for prompt identification of haematologic/hepatic toxicity safe dose adjustment, and treatment modification in cases of suboptimal clinical outcome or non-compliance. Well designed RCTs for the identification of robust surrogate markers of thiopurine efficacy and toxicity are required.
authors.affiliation: Department of Clinical and Molecular Pharmacology, Wolfson Centre for Personalised Medicine, Institute for Translational Medicine, University of Liverpool, Liverpool, UK.
authors.forename: Anastasia
authors.initials: A
authors.lastname: Konidari
authors.forename: Antonios
authors.initials: A
authors.lastname: Anagnostopoulos
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Bonnett
authors.forename: Munir
authors.initials: M
authors.lastname: Pirmohamed
authors.forename: Wael
authors.initials: W
authors.lastname: El-Matary
mesh_terms: D056486:Chemical and Drug Induced Liver Injury / Q000175:diagnosis / Q000209:etiology; D002648:Child; D016903:Drug Monitoring / Q000379:methods; D006801:Humans; D007166:Immunosuppressive Agents / Q000009:adverse effects / Q000378:metabolism / Q000627:therapeutic use*; D015212:Inflammatory Bowel Diseases / Q000188:drug therapy*; D007958:Leukocyte Count; D055118:Medication Adherence; D011687:Purines / Q000009:adverse effects / Q000378:metabolism / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D007166:Immunosuppressive Agents; D011687:Purines
keywords: drug monitoring; inflammatory bowel disease; thiopurine