For the main outcome of post-operative nausea and vomiting there were 65 trials with 63 placebo controlled comparisons (six dolasetron, 20 granisetron, 28 ondansetron, nine tropisetron) and seven comparisons of two drugs. There were a total of 7,903 patients.
All four drugs significantly reduced nausea and vomiting when compared with placebo (dolasetron: OR 2.65, 95% CI 1.99 to 3.75; granisetron: OR 4.45, 95% CI 3.55 to 5.55; ondansetron: OR 2.90, 95% CI 2.43 to 3.51; tropisetron: OR 3.12, 95% CI 2.31 to 4.29). Granisetron was significantly better than dolasetron (OR: 1.67, 95% CI: 1.12 to 2.38) and than ondansetron (OR: 1.53, 95% CI: 1.15 to 2.00). No other significant differences between drugs were identified. Analyses of subgroups of trials (such as including only higher-quality trials) gave results similar to the primary analysis.
For the second outcome of post-operative vomiting there were 55 trials, 54 placebo controlled comparisons and one comparison of two drugs. There were a total of 11,863 patients. All four drugs were found to significantly reduce post-operative vomiting when compared with placebo. No significant differences were identified for between-drug comparisons.