Table 3.

Overall results of the meta-analysis

Outcomes	WMD/RR (95%CI)	P	I2
Morphine consumption (mg)
Overall	3.893 (2.053, 5.733)	< 0.001	72.7
Operation types
Abdominal surgery	2.400 (1.825, 2.975)	< 0.001	NA
Pelvic surgery	4.731 (2.634, 6.829)	< 0.001	44.5
Quality
High-quality	3.205 (1.283, 5.127)	0.001	76.2
Low-quality	6.443 (0.098, 12.788)	0.047	72.2
Fentanyl consumption (μg)
Overall	23.815 (15.521, 32.109)	< 0.001	96.0
Operation types
Abdominal surgery	14.077 (7.412, 20.742)	< 0.001	92.3
Pelvic surgery	34.808 (14.079, 55.537)	0.001	96.5
Quality
High-quality	26.576 (13.594, 39.558)	< 0.001	96.9
Low-quality	16.264 (7.527, 25.000)	< 0.001	73.3
Operative time
Overall	0.324 (−0.805, 1.454)	0.573	0.0
Duration of anesthesia (min)
Overall	-2.139 (−14.423, 10.146)	0.733	80.8
VAS score at 24 h postoperatively
Overall	0.459 (0.118, 0.801)	0.008	94.8
Operation types
Abdominal surgery	0.224 (−0.033, 0.480)	0.088	80.1
Pelvic surgery	0.671 (0.103, 1.240)	0.021	95.4
Quality
High-quality	0.576 (0.048, 1.104)	0.032	96.3
Low-quality	0.218 (−0.019, 0.455)	0.071	66.1
Duration of postoperative analgesia
Overall	-21.882 (−59.774, 16.010)	0.258	100.0
Operation types
Abdominal surgery	-3.400 (−4.038, −2.762)	< 0.001	NA
Pelvic surgery	−31.125 (−78.851, 16.600)	0.201	100.0
Number of patients requiring analgesia postoperatively
Overall	2.618 (2.040, 3.361)	< 0.001	13.2
Adverse reactions
Dizziness
Overall	2.691 (1.653, 4.382)	< 0.001	0.0
Nausea and vomiting
Overall	1.918 (0.805, 4.571)	0.141	50.9
Quality
High-quality	4.100 (1.932, 8.699)	< 0.001	0.0
Low-quality	0.417 (0.054, 3.239)	0.403	70.9

CI confidence interval, RR, risk ratio, WMD weighted mean difference, VAS visual analog scal, NA unavailable