Eleven RCTs (1,801 patients, range 40 to 614) were included in the review.
During time in the post-anaesthesia care unit, significant reductions were observed with prophylactic administration of dexamethasone compared to placebo in nausea (OR 0.51, 95% CI 0.31 to 0.84; six trials), vomiting (OR 0.31, 95% CI 0.17 to 0.56; five trials), postoperative nausea and vomiting (OR 0.33, 95% CI 0.21 to 0.50; six trials) and need for rescue antiemetic (OR 0.22, 95% CI 0.10 to 0.49; three trials).
Similar significant reductions in the incidence of complications were observed in the first 24 hours post surgery with dexamethasone-treated patients compared to placebo-treated patients in nausea (OR 0.46, 95% CI 0.32 to 0.66; eight trials), vomiting (OR 0.27, 95% CI 0.19 to 0.40; eight trials), postoperative nausea and vomiting (OR 0.18, 95% CI 0.13 to 0.26; eight trials) and need for rescue antiemetic (OR 0.26, 95% CI 0.16 to 0.41; three trials).
There were no statistically significant differences between dexamethasone groups and placebo-treated groups for incidence of rescue analgesia but there was a trend towards reduced requirement in the dexamethasone group (OR 0.68, 95% CI 0.40 to 1.18; four trials). Little statistically significant heterogeneity was observed between the trials (I²=0% for most of the outcomes).