title: Dexamethasone to prevent postoperative nausea and vomiting: an updated meta-analysis of randomized controlled trials.
abstract: BACKGROUND
  Dexamethasone has an established role in decreasing postoperative nausea and vomiting (PONV); however, the optimal dexamethasone dose for reducing PONV when it is used as a single or combination prophylactic strategy has not been clearly defined. In this study, we evaluated the use of 4 mg to 5 mg and 8 mg to 10 mg IV doses of dexamethasone to prevent PONV when used as a single drug or as part of a combination preventive therapy.
  
  
  METHODS
  A wide search was performed to identify randomized clinical trials that evaluated systemic dexamethasone as a prophylactic drug to reduce postoperative nausea and/or vomiting. The effects of dexamethasone dose were evaluated by pooling studies into 2 groups: 4 mg to 5 mg and 8 mg to 10 mg. The first group represents the suggested dexamethasone dose to prevent PONV by the Society for Ambulatory Anesthesia (SAMBA) guidelines, and the second group represents twice the dose range recommended by the guidelines. The SAMBA guidelines were developed in response to studies, which have been performed to examine different dosages of dexamethasone.
  
  
  RESULTS
  Sixty randomized clinical trials with 6696 subjects were included. The 4-mg to 5-mg dose dexamethasone group experienced reduced 24-hour PONV compared with control, odds ratio (OR, 0.31; 95% confidence interval [CI], 0.23-0.41), and number needed to treat (NNT, 3.7; 95% CI, 3.0-4.7). When used together with a second antiemetic, the 4-mg to 5-mg dexamethasone group also experienced reduced 24-hour PONV compared with control (OR, 0.50; 95% CI, 0.35-0.72; NNT, 6.6; 95% CI, 4.3-12.8). The 8-mg to 10-mg dose dexamethasone group experienced decreased 24-hour PONV compared with control (OR, 0.26; 95% CI, 0.20-0.32; NNT, 3.8; 95% CI, 3.0-4.3). Asymmetric funnel plots were observed in the 8-mg to 10-mg dose analysis, suggesting the possibility of publication bias. When used together with a second antiemetic, the 8-mg to 10-mg dose group also experienced reduced incidence of 24-hour PONV (OR, 0.35; 95% CI, 0.22-0.53; NNT, 6.2; 95% CI, 4.5-10). In studies that provided a direct comparison between groups, there was no clinical advantage of the 8-mg to 10-mg dexamethasone dose compared with the 4-mg to 5-mg dose on the incidence of postoperative nausea and/or vomiting.
  
  
  CONCLUSIONS
  Our results showed that a 4-mg to 5-mg dose of dexamethasone seems to have similar clinical effects in the reduction of PONV as the 8-mg to 10-mg dose when dexamethasone was used as a single drug or as a combination therapy. These findings support the current recommendation of the SAMBA guidelines for PONV, which favors the 4-mg to 5-mg dose regimen of systemic dexamethasone.
authors.affiliation: MSCI, Department of Anesthesiology, Northwestern Memorial Hospital, 251 E Huron St, F5-704, Chicago, IL 60611, USA. G-jr@northwestern.edu
authors.forename: Gildasio S
authors.initials: GS
authors.lastname: De Oliveira
authors.forename: Lucas J Santana
authors.initials: LJ
authors.lastname: Castro-Alves
authors.forename: Shireen
authors.initials: S
authors.lastname: Ahmad
authors.forename: Mark C
authors.initials: MC
authors.lastname: Kendall
authors.forename: Robert J
authors.initials: RJ
authors.lastname: McCarthy
mesh_terms: D000932:Antiemetics / Q000627:therapeutic use*; D003627:Data Interpretation, Statistical; D003907:Dexamethasone / Q000627:therapeutic use*; D006801:Humans; D007275:Injections, Intravenous; D020250:Postoperative Nausea and Vomiting / Q000453:epidemiology / Q000517:prevention & control*; D016032:Randomized Controlled Trials as Topic; D015203:Reproducibility of Results; D016896:Treatment Outcome
chemical_list: D000932:Antiemetics; D003907:Dexamethasone