Five RCTs (n=363) were included. An additional study in which 0.3 or 0.6 g of ginger was administered was later included in a sensitivity analysis (n=116).
Overall, ginger at a fixed dose of 1 g or greater was associated with a statistically significant decrease in the incidence of 24-hour PONV (RR 0.65, 95% CI: 0.51, 0.84; 3 RCTs) and POV (RR 0.62, 95% CI: 0.46, 0.84; 5 RCTs) compared with placebo.
The authors performed a sensitivity analysis by including an additional study in which the dose of ginger was 0.3 or 0.6 g. By including this study ginger was still associated with a statistically significant decrease in the incidence of PONV (RR 0.74, 95% CI: 0.56, 0.98), but the difference in incidence of POV was no longer statistically significant (RR 0.75, 95% CI: 0.52, 1.07).
One adverse effect (abdominal discomfort) was reported in the intervention group in one study.
Four studies had a Jadad score of 3 for quality, whilst the other included study had a score of 4. None of the studies reported the amount of active ingredients or the quality of the ginger preparation. No data on publication bias or statistically significant heterogeneity was reported.