The authors included 13 studies with 1,628 patients. All included studies met the validity criteria.
There were four studies of 477 children who underwent tonsillectomy or adenotonsillectomy; one study was reported as randomised. The percentage of children who vomited in the dexamethasone group was between 20% and 23% compared to between 51% and 56% in the placebo group. This was significantly different in both studies that reported this outcome. The use of anti-emetic medication was between 3% and 4% in the dexamethasone group compared to between 10% and 22% in the two studies that reported this outcome; neither of these was reported as significantly different. One study also reported that retching and/or vomiting was significantly lower in the dexamethasone group (48%) compared to the placebo group (88%).
There were two randomly allocated studies of 158 patients undergoing laparoscopic cholecystectomy. Over 24 hours the incidence of vomiting was between 5% and 10% in the dexamethasone group and between 25% and 34% in the placebo group; a significantly lower incidence in the dexamethasone group in both studies. The reported rates of nausea were between 13% and 30% compared to between 29% and 47% in the saline group; incidence was not reported as significantly different in either study. In the dexamethasone group, 20% of patients were reported to have received anti-emetic medication compared to 37.5% in the saline group; this difference was not reported as significantly different in the one study that reported this outcome.
The outcomes of vomiting, nausea and anti-emetic medication were reported in all five studies of 482 patients undergoing gynaecological procedures; two were randomly allocated. The percentage of patients in the dexamethasone group with nausea ranged from 14.3% to 25%, vomiting ranged from 8% to 30% and the use of anti-emetics from 7% to 20%. In the saline group the rates of nausea were between 25% and 62.5%, vomiting between 24.4% and 60% and use of anti-emetic medication was between 28% and 62.5%. Vomiting was reported as significantly lower in the dexamethasone group in two studies, nausea was significantly lower in one subgroup in one study and the use of anti-emetic medication was significantly lower in one study.
In the one non-randomised study of 294 patients having coronary revascularization procedures, the rates of vomiting (17%), nausea (36%) and anti-emetic use (30%) in the dexamethasone group were reported as not significantly different to those in the saline group (22% vomiting, 42% nausea and 42% anti-emetic use).
The rates of nausea were between 7% and 14% in the dexamethasone group in the one non-randomised study of 225 patients undergoing thyroidectomy compared to between 19% and 33% in the saline group. This was only significantly lower in the subgroup of patients receiving a 5 mg dose of dexamethasone. The use of anti-emetic medication was between 11% and 12% in the dexamethasone group, which was significantly lower than its 35% use with patients in the saline group.