title: Azathioprine and 6-mercaptopurine in Crohn disease. A meta-analysis.
abstract: OBJECTIVE
  To assess the effectiveness of azathioprine and 6-mercaptopurine in inducing remission of active Crohn disease and the effectiveness of azathioprine in maintaining remission of quiescent disease.
  
  
  METHODS
  Pertinent studies were selected from the MEDLINE database (1966 to May 1994), abstracts from major gastrointestinal meetings, and references from published articles and reviews.
  
  
  METHODS
  Nine randomized, placebo-controlled trials of azathioprine or 6-mercaptopurine therapy were identified: Four addressed active disease, two addressed quiescent disease, and three had multiple therapeutic arms.
  
  
  METHODS
  Data were extracted by three independent observers on the basis of the intention-to-treat principle and were analyzed with logistic regression. Each study was given a quality score on the basis of predetermined criteria.
  
  
  RESULTS
  Compared with placebo, azathioprine or 6-mercaptopurine therapy had an odds ratio of response of 3.09 (95% CI, 2.45 to 3.91) in patients with active Crohn disease. When the single trial that used 6-mercaptopurine in active disease was excluded from the analysis, the odds ratio of response was 1.45 (CI, 1.12 to 1.87). No trials of quiescent disease used 6-mercaptopurine; the odds ratio of response in these trials of quiescent disease was 2.27 (CI, 1.76 to 2.93). For active disease, continuation of therapy for at least 17 weeks improved response (P = 0.03). For quiescent disease, a higher dose improved response (P = 0.008). Increased cumulative dose improved response in both groups (P < 0.001 for active disease and P = 0.01 for quiescent disease). A steroid-sparing effect was seen in active disease (odds ratio, 3.69 (CI, 2.12 to 6.42) and in quiescent disease (odds ratio, 4.64 [CI, 1.00 to 21.54]). Fistulae improved with therapy (odds ratio, 4.44 [CI, 1.50 to 13.20]). Adverse events requiring withdrawal from a trial, primarily allergy, leukopenia, pancreatitis, and nausea, were increased with therapy (odds ratio, 5.26 [CI, 2.20 to 12.60]).
  
  
  CONCLUSIONS
  Azathioprine and 6-mercaptopurine are effective in treating active Crohn disease and in maintaining remission. Cumulative dose was an important factor in predicting response. Adverse effects were more common among patients receiving therapy.
authors.affiliation: University of Calgary, Alberta, Canada.
authors.forename: D C
authors.initials: DC
authors.lastname: Pearson
authors.forename: G R
authors.initials: GR
authors.lastname: May
authors.forename: G H
authors.initials: GH
authors.lastname: Fick
authors.forename: L R
authors.initials: LR
authors.lastname: Sutherland
mesh_terms: D001379:Azathioprine / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D003424:Crohn Disease / Q000150:complications / Q000188:drug therapy*; D004334:Drug Administration Schedule; D006801:Humans; D007412:Intestinal Fistula / Q000188:drug therapy / Q000209:etiology; D015122:Mercaptopurine / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D016017:Odds Ratio; D016032:Randomized Controlled Trials as Topic; D012074:Remission Induction
chemical_list: D015122:Mercaptopurine; D001379:Azathioprine