Table 3.

The results of subgroup analysis

Outcomes	Subgroups	Effect estimate
		Studies	χ2	MD and 95% CI	I 2 (%)	P
VAS at POD0	CFNB	2	0.07	0.42(−0.02,0.86)	0	0.8
	SFNB	4	35.91	0.03(−0.73,0.78)	92	<0.00001
VAS at POD1	CFNB	2	0.17	0.49(0.09,0.9)	0	0.68
	SFNB	3	23.53	'‐0.48(−1.54,0.59)	91	<0.00001
Total morphine	CFNB	2	0.01	−70.97(−104.11, −37.83)	0	0.93
	SFNB	4	535.92	−36.51(−82.86,9.83)	99	<0.00001
LOS	CFNB	4	1.85	−0.36(−0.53,−0.19)	0	0.6
	SFNB	5	11.82	−0.22(−0.41,−0.03)	66	0.02