title: A quantitative systematic review of ondansetron in treatment of established postoperative nausea and vomiting.
abstract: OBJECTIVE
  To test the evidence for a dose-response with ondansetron for treatment of postoperative nausea and vomiting and to establish whether differences in efficacy between doses are of clinical relevance.
  
  
  METHODS
  Quantitative systematic review of published randomised controlled trials.
  
  
  METHODS
  Seven trials from 1991 to January 1996 retrieved from a systematic literature search (Medline, reference lists, hand searching of anaesthetic journals, manufacturer's database); no restriction on language.
  
  
  METHODS
  Estimation of efficacy (incidence of complete control of further nausea and vomiting) by using odds ratios and the "number needed to treat" method for early (within 6 hours of administration) and late (within 24 hours) periods.
  
  
  RESULTS
  Four placebo controlled trials with 1043 patients studied intravenous ondansetron 1 mg, 4 mg, or 8 mg. All doses were more efficacious than placebo in preventing further episodes of nausea or vomiting. For combined data, the point estimates for the number needed to treat were between 3.1 (8 mg) and 3.8 (1 mg) for early efficacy and between 4.1 (8 mg) and 4.8 (1 mg) for late efficacy, without significant differences between doses. No difference was found between ondansetron and droperidol in two trials with 129 patients or between ondansetron and metoclopramide in one trial with 80 patients.
  
  
  CONCLUSIONS
  Further nausea and vomiting could be prevented with ondansetron compared with placebo in 25% of patients who had nausea or vomiting (number needed to treat, about 4). There was no evidence of a clinically relevant dose-response between 1 mg and 8 mg or a difference between ondansetron and either droperidol or metoclopramide in a limited dataset. A false impression of ondansetron's efficacy may arise because a quarter of all relevant published reports are duplicates, and reporting of study results is uncritical.
authors.affiliation: Department of Anaesthetics, Churchill Oxford, Radcliffe Hospital. martin.tramer%mailgate.jr2@ox.ac.uk
authors.forename: M R
authors.initials: MR
authors.lastname: Tramèr
authors.forename: R A
authors.initials: RA
authors.lastname: Moore
authors.forename: D J
authors.initials: DJ
authors.lastname: Reynolds
authors.forename: H J
authors.initials: HJ
authors.lastname: McQuay
mesh_terms: D000932:Antiemetics / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D009325:Nausea / Q000517:prevention & control*; D017294:Ondansetron / Q000627:therapeutic use*; D011183:Postoperative Complications / Q000517:prevention & control*; D016032:Randomized Controlled Trials as Topic / Q000592:standards; D016896:Treatment Outcome; D014839:Vomiting / Q000517:prevention & control*
chemical_list: D000932:Antiemetics; D017294:Ondansetron