| Subgroup analysis | Studies | SMD (95% CI) | | | (%) | 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 | — | — | — |
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