Rational study design for prophylaxis of postoperative nausea and vomiting

To the editor： In the recent article of Fang and colleagues1 ssessing prophylactic efficacy of a single-dose of dexamethasone before anesthesia induction on postoperative nausea and vomiting （PONV） in patients undergoing microvascular decompression for facial spasm, they showed that dexamethasone did not prevent PONV. Actually, meta-analyses of double-blind randomized controlled trials comparing dexamethasone with controls indicate that this antiemetic is effective in the prophylaxis of postoperative vomiting and reduced use of rescue antiemetics.2 In our views, some limitations of this study design may have made interpretation of their conclusions questionable.