Comparison 2. Pre‐incisional and postoperative ketamine versus control in a non‐stratified patient population.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
2.1 Opioid consumption at 24 hours	28	1639	Mean Difference (IV, Random, 95% CI)	‐6.26 [‐8.42, ‐4.11]
2.1.1 Pre‐incisional ketamine	19	1045	Mean Difference (IV, Random, 95% CI)	‐5.54 [‐7.95, ‐3.12]
2.1.2 Postoperative ketamine	9	594	Mean Difference (IV, Random, 95% CI)	‐8.66 [‐13.84, ‐3.49]
2.2 Opioid consumption at 48 hours	16	959	Mean Difference (IV, Random, 95% CI)	‐10.76 [‐14.84, ‐6.68]
2.2.1 Pre‐incisional ketamine	9	534	Mean Difference (IV, Random, 95% CI)	‐3.88 [‐7.04, ‐0.72]
2.2.2 Postoperative ketamine	7	425	Mean Difference (IV, Random, 95% CI)	‐20.81 [‐27.39, ‐14.24]
2.3 Pain intensity at 24 hours	29	1646	Mean Difference (IV, Random, 95% CI)	‐7.08 [‐9.56, ‐4.59]
2.3.1 Pre‐incisional ketamine	20	1075	Mean Difference (IV, Random, 95% CI)	‐6.65 [‐10.06, ‐3.24]
2.3.2 Postoperative ketamine	9	571	Mean Difference (IV, Random, 95% CI)	‐8.30 [‐12.55, ‐4.05]
2.4 Pain intensity at 48 hours	15	840	Mean Difference (IV, Random, 95% CI)	‐5.49 [‐7.72, ‐3.25]
2.4.1 Pre‐incisional ketamine	9	509	Mean Difference (IV, Random, 95% CI)	‐4.36 [‐7.53, ‐1.19]
2.4.2 Postoperative ketamine	6	331	Mean Difference (IV, Random, 95% CI)	‐8.02 [‐15.79, ‐0.26]
2.5 Time to first request for analgesia/first trigger of PCA	13	643	Mean Difference (IV, Random, 95% CI)	37.70 [20.87, 54.52]