Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Nausea	14		Risk Ratio (IV, Random, 95% CI)	Subtotals only
1.1 Ondansetron	9	843	Risk Ratio (IV, Random, 95% CI)	0.86 [0.65, 1.13]
1.2 Metoclopramide	4	334	Risk Ratio (IV, Random, 95% CI)	0.72 [0.38, 1.36]
1.3 Cyclizine	1	62	Risk Ratio (IV, Random, 95% CI)	0.5 [0.14, 1.82]
1.4 Droperidol	2	143	Risk Ratio (IV, Random, 95% CI)	1.02 [0.47, 2.19]
1.5 All antiemetics combined	14	1332	Risk Ratio (IV, Random, 95% CI)	0.91 [0.75, 1.10]
1.6 Children	1	99	Risk Ratio (IV, Random, 95% CI)	0.68 [0.41, 1.13]
1.7 Adult	11	1033	Risk Ratio (IV, Random, 95% CI)	0.96 [0.78, 1.17]
1.8 Invasive PC6 stimulation	5	559	Risk Ratio (IV, Random, 95% CI)	0.69 [0.41, 1.14]
1.9 Noninvasive PC6 stimulation	9	773	Risk Ratio (IV, Random, 95% CI)	0.95 [0.78, 1.16]
1.10 Low risk of bias trials	1	51	Risk Ratio (IV, Random, 95% CI)	0.48 [0.19, 1.21]
1.11 Unclear risk of bias trials	8	975	Risk Ratio (IV, Random, 95% CI)	0.81 [0.63, 1.04]
1.12 High risk of bias trials	5	306	Risk Ratio (IV, Random, 95% CI)	1.07 [0.89, 1.29]
1.13 Trials with control event rate less than or equal to 20%	6	685	Risk Ratio (IV, Random, 95% CI)	0.89 [0.52, 1.52]
1.14 Trials with control event rate more than 20%	8	647	Risk Ratio (IV, Random, 95% CI)	0.88 [0.69, 1.13]
2 Vomiting	19		Risk Ratio (IV, Random, 95% CI)	Subtotals only
2.1 Ondansetron	9	843	Risk Ratio (IV, Random, 95% CI)	1.02 [0.68, 1.54]
2.2 Metoclopramide	5	414	Risk Ratio (IV, Random, 95% CI)	0.87 [0.43, 1.74]
2.3 Prochlorperazine	2	173	Risk Ratio (IV, Random, 95% CI)	1.15 [0.48, 2.77]
2.4 Cyclizine	1	62	Risk Ratio (IV, Random, 95% CI)	0.67 [0.21, 2.13]
2.5 Droperidol	4	266	Risk Ratio (IV, Random, 95% CI)	0.96 [0.64, 1.43]
2.6 All antiemetics combined	19	1708	Risk Ratio (IV, Random, 95% CI)	0.93 [0.74, 1.17]
2.7 Children	3	237	Risk Ratio (IV, Random, 95% CI)	0.98 [0.61, 1.56]
2.8 Adult	14	1271	Risk Ratio (IV, Random, 95% CI)	0.94 [0.72, 1.22]
2.9 Invasive PC6 stimulation	8	734	Risk Ratio (IV, Random, 95% CI)	0.99 [0.70, 1.41]
2.10 Noninvasive PC6 stimulation	12	974	Risk Ratio (IV, Random, 95% CI)	0.90 [0.67, 1.21]
2.11 Low risk of bias trials	1	51	Risk Ratio (IV, Random, 95% CI)	1.44 [0.26, 7.92]
2.12 Unclear risk of bias trials	8	975	Risk Ratio (IV, Random, 95% CI)	0.96 [0.66, 1.40]
2.13 High risk of bias trials	10	682	Risk Ratio (IV, Random, 95% CI)	0.91 [0.68, 1.21]
2.14 Trials with control event rate less than or equal to 20%	15	1440	Risk Ratio (IV, Random, 95% CI)	0.95 [0.70, 1.29]
2.15 Trials with control event rate more than 20%	4	268	Risk Ratio (IV, Random, 95% CI)	0.93 [0.60, 1.43]
3 Rescue antiemetic	9	895	Risk Ratio (IV, Random, 95% CI)	0.87 [0.65, 1.16]