title: Azathioprine and 6-mercaptopurine for maintenance of remission in ulcerative colitis.
abstract: BACKGROUND
  Maintenance of remission is a major issue in inflammatory bowel disease. In ulcerative colitis, the evidence for the effectiveness of azathioprine and 6-mercaptopurine for the maintenance of remission is still controversial.
  
  
  OBJECTIVE
  To assess the effectiveness and safety of azathioprine and 6-mercaptopurine for maintaining remission of ulcerative colitis.
  
  
  METHODS
  The MEDLINE database was used to search literature from 1966 to 2006. A manual search was also performed using references from these articles as well as review articles, proceedings from major gastrointestinal meetings and data available from the Cochrane Collaboration database. Authors of maintenance trials were asked about unpublished studies.
  
  
  METHODS
  Randomized controlled trials of at least 12 months duration that compared azathioprine or 6-mercaptopurine with placebo or standard maintenance therapy (mesalamine) were included.
  
  
  METHODS
  Data were extracted by two raters using standard forms. Disagreements were solved by informal consent, including a third rater. Jadad scores were applied to assess study quality. Analyses were performed separately by type of control (placebo, or active comparator). Pooled odds ratios were calculated based on the fixed effects model unless heterogeneity was shown.
  
  
  RESULTS
  Six studies were identified including 286 patients with ulcerative colitis. The study quality was mostly poor. Azathioprine was shown to be superior for the maintenance of remission as compared to placebo based on four trials (failure to maintain remission: OR 0.41; 95% CI 0.24 to 0.70). Two trials that compared 6-mercaptopurine to mesalazine, or azathioprine to sulfasalazine showed significant heterogeneity. Both studies using active comparators were open label. Adverse effects occurred in 11 of 127 patients receiving azathioprine, including acute pancreatitis (3 cases) and significant bone marrow suppression (5 cases).
  
  
  CONCLUSIONS
  Azathioprine may be an effective maintenance therapy for patients who have failed or cannot tolerate mesalazine or sulfasalazine and for patients who require repeated courses of steroids. More research is needed to evaluate superiority over standard maintenance therapy, especially in the light of a potential for adverse events from azathioprine.
authors.affiliation: German Cochrane Center, Stefan Meier Str. 26, Freiburg, Germany, 79104. timmer@cochrane.de
authors.forename: A
authors.initials: A
authors.lastname: Timmer
authors.forename: J W D
authors.initials: JW
authors.lastname: McDonald
authors.forename: J K
authors.initials: JK
authors.lastname: Macdonald
mesh_terms: D000963:Antimetabolites / Q000009:adverse effects / Q000627:therapeutic use*; D001379:Azathioprine / Q000009:adverse effects / Q000627:therapeutic use*; D003093:Colitis, Ulcerative / Q000188:drug therapy*; D006801:Humans; D015122:Mercaptopurine / Q000009:adverse effects / Q000627:therapeutic use*; D016032:Randomized Controlled Trials as Topic; D012074:Remission Induction; D055502:Secondary Prevention
chemical_list: D000963:Antimetabolites; D015122:Mercaptopurine; D001379:Azathioprine