Table 4.

Subgroup analysis of primary outcomes.

Subgroup analysis		Studies	SMD (95% CI)	P	χ 2	I 2 (%)	Tau2
DOSS
Duration	≤2 w	2	1.67 [1.14, 2.19]	<0.0001	0	0%	0
	2 w to 6 m	5	1.67 [1.14, 2.19]	0.0008	25.60	84%	0.92
	≥6 m	1	0.33 [-0.45, 1.10]	0.41	—	—	—
Intervention length	≤2 w	6	1.18 [0.44, 1.91]	0.002	22.85	78%	0.64
	>2 w	2	2.17 [1.20, 3.13]	<0.0001	3.62	72%	0.35
Stimulation site	Unaffected side	3	1.67 [1.24, 2.09]	<0.0001	0	0%	0
	Affected side	3	1.15 [-0.25, 2.55]	0.11	14.92	87%	1.32
	Bilateral	2	1.50 [-0.79, 3.78]	0.2	18.97	95%	2.57
SSA
Duration	≤2 w	1	-0.65 [-1.15, -0.14]	0.01	—	—	—
	2 w to 6 m	5	-0.93 [-1.42, -0.43]	0.0002	15.34	74%	0.23
	Not given	1	-2.03 [-2.65, -1.40]	<0.0001	—	—	—
Intervention length	≤2 w	5	-1.22 [-1.83, -0.61]	<0.0001	21.07	81%	0.38
	>2 w	2	-0.65 [-1.43, 0.14]	0.10	4.7	79%	0.25
Stimulation site	Unaffected side	3	-1.14 [-1.99, -0.29]	0.008	12.34	84%	0.47
	Affected side	1	-0.73 [-1.20, -0.25]	0.003	—	—	—
	Bilateral	3	-1.09 [-2.00, -0.17]	0.02	14.64	86%	0.56
PAS
Duration	2 w to 6 m	8	-0.85 [-1.33, -0.36]	0.0006	25.72	73%	0.35
Intervention length	≤2 w	7	-0.61 [-0.87, -0.35]	<0.0001	4.99	0%	0
	>2 w	1	-2.25 [-2.91, -1.59]	<0.0001	—	—	—
Stimulation site	Unaffected side	5	-0.68 [-1.05, -0.32]	<0.0001	4.49	11%	0.02
	Affected side	2	-0.50 [-0.92, -0.09]	0.01	0.07	0%	0
	Bilateral	1	-2.25 [-2.91, -1.59]	<0.0001	—	—	—