title: Allopurinol to prevent pancreatitis after endoscopic retrograde cholangiopancreatography: a randomized placebo-controlled trial.
abstract: OBJECTIVE
  Endoscopic retrograde cholangiopancreatography (ERCP) is associated with a risk of pancreatitis (PEP). Animal studies suggest that (single-dose) allopurinol (xanthine oxidase inhibitor with high oral bioavailability and long-lasting active metabolites) may reduce this risk; human study results are conflicting. The aim of this study was to determine if allopurinol decreases the rate of PEP.
  
  
  METHODS
  Patients referred for ERCP to 9 endoscopists at 2 tertiary centers were randomized to receive either allopurinol 300 mg or identical placebo orally 60 minutes before ERCP, stratified according to high-risk ERCP (manometry or pancreatic therapy). The primary outcome (PEP) was adjudicated blindly; pancreatitis was defined according to the Cotton consensus, and evaluated at 48 hours and 30 days. Secondary outcomes included severe PEP, length of stay, and mortality (nil). The trial was terminated after the blinded (midpoint) interim analysis, as recommended by the independent data and safety monitoring committee.
  
  
  RESULTS
  We randomized 586 subjects, 293 to each arm. The crude PEP rates were 5.5% (allopurinol) and 4.1% (placebo), (P = .44; difference = 1.4%; 95% confidence interval, -2.1% to 4.8%). The Mantel-Haenszel combined risk ratio for PEP with allopurinol, considering stratification, was 1.37 (95% confidence interval, 0.65-2.86). Subgroup analyses suggested nonsignificant trends toward possible benefit in the high-risk group, and possible harm for the remaining subjects. Logistic regression found pancreatic therapy, pancreatic injection, and prior PEP to be the only independent predictors of PEP.
  
  
  CONCLUSIONS
  Allopurinol does not appear to reduce the overall risk of PEP; however, its potential benefit in the high-risk group (but potential harm for non-high-risk patients) means further study is required.
authors.affiliation: Digestive Disease Center, Department of Medicine, Medical University of South Carolina, South Carolina 29425, USA. romagnuo@musc.edu
authors.forename: Joseph
authors.initials: J
authors.lastname: Romagnuolo
authors.forename: Robert
authors.initials: R
authors.lastname: Hilsden
authors.forename: Gurpal S
authors.initials: GS
authors.lastname: Sandha
authors.forename: Marty
authors.initials: M
authors.lastname: Cole
authors.forename: Syd
authors.initials: S
authors.lastname: Bass
authors.forename: Gary
authors.initials: G
authors.lastname: May
authors.forename: Jonathan
authors.initials: J
authors.lastname: Love
authors.forename: Vincent G
authors.initials: VG
authors.lastname: Bain
authors.forename: John
authors.initials: J
authors.lastname: McKaigney
authors.forename: Richard N
authors.initials: RN
authors.lastname: Fedorak
mesh_terms: D000367:Age Factors; D000493:Allopurinol / Q000627:therapeutic use*; D002760:Cholangiopancreatography, Endoscopic Retrograde / Q000009:adverse effects*; D004311:Double-Blind Method; D005260:Female; D016166:Free Radical Scavengers / Q000627:therapeutic use*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D010195:Pancreatitis / Q000209:etiology / Q000517:prevention & control*; D011292:Premedication
chemical_list: D016166:Free Radical Scavengers; D000493:Allopurinol