title: Dexamethasone for the prevention of acute mountain sickness: systematic review and meta-analysis.
abstract: BACKGROUND
  AMS is a disease that occurs when accessing high altitude (HA) or upon exposure to a higher altitude after acclimatising over 3,000 m. Evidence shows that drugs can prevent AMS. The function of dexamethasone for preventing AMS is important. No systematic review has previously been published about the effect of dexamethasone. The effect of intervention is unclear, which has limited the use of dexamethasone in the prevention of AMS.
  
  
  METHODS
  We searched PubMed and Embase for studies from inception to July 2013. We selected randomised controlled trials including dexamethasone versus placebo as prophylaxis for AMS. The studies included were required to provide a clear dose of dexamethasone, the final altitude and clear diagnostic criteria used to judge the AMS severity of symptoms and incidence. Finally, 8 studies were included in this review. There were 116 participants in the experimental groups and 110 in the control groups. Three different doses of dexamethasone were used in these studies (8, 12, and 16 mg/d).
  
  
  RESULTS
  Eight of the 79 considered studies were eventually added to the meta-analysis. We used the fixed-effect model (RevMan 5.0) based on the heterogeneity (I(2)=0%, p=0.43). Dexamethasone could reduce the incidence of AMS with an odds ratio of 6.03 (95% CI, 2.23 to 21.00) for dexamethasone compared with placebo; the p value for overall effect was less than 0.00001.
  
  
  CONCLUSIONS
  Our systematic review suggests that oral dexamethasone is effective in preventing AMS. Additionally, there is some evidence that the effect of dexamethasone is related to height and dosage.
authors.affiliation: Battalion 8 of Cadet Brigade, Third Military Medical University, Chongqing 400038, PR China; Department of Military Medical Geography, Third Military Medical University, Chongqing 400038, PR China; Key Laboratory of High Altitude Medicine (Ministry of Education), Third Military Medical University, Chongqing 400038, PR China.
authors.forename: Enjie
authors.initials: E
authors.lastname: Tang
authors.affiliation: Key Laboratory of High Altitude Medicine (Ministry of Education), Third Military Medical University, Chongqing 400038, PR China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Military Medical Geography, Third Military Medical University, Chongqing 400038, PR China; Key Laboratory of High Altitude Medicine (Ministry of Education), Third Military Medical University, Chongqing 400038, PR China. Electronic address: luoyongjun2011@gmail.com.
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Luo
mesh_terms: D000208:Acute Disease; D000531:Altitude; D000532:Altitude Sickness / Q000517:prevention & control*; D003907:Dexamethasone / Q000008:administration & dosage*; D005938:Glucocorticoids / Q000008:administration & dosage*; D006801:Humans; D009051:Mountaineering
chemical_list: D005938:Glucocorticoids; D003907:Dexamethasone
keywords: Acute mountain sickness (AMS); Dexamethasone; Prophylaxis