Table 3.
Subgroup analyses.
| Subgroups | No. of studies | Mean difference [95% CI] | P value | I 2 (%) | Between subgroup significance |
|---|---|---|---|---|---|
| Pain intensity at rest at 1 h postoperatively | |||||
| Total | 10 | −1.57 [−1.94, −1.20] | 0.00001 | 89 | |
| Allocation concealment | |||||
| Adequate | 4 | −1.58 [−2.15, −1.01] | 0.00001 | 83 | 0.95 |
| Unclear | 6 | −1.55 [−2.07, −1.04] | 0.00001 | 92 | |
| Local anesthetic use | |||||
| Yes | 5 | −1.13 [−1.34, −0.93] | 0.00001 | 50 | 0.0001 |
| No | 5 | −2.11 [−2.50, −1.73] | 0.00001 | 59 | |
| Postoperative analgesics | |||||
| Opioids | 6 | −1.41 [−1.86, −0.96] | 0.00001 | 90 | 0.31 |
| None opioids | 4 | −1.83 [−2.50, −1.15] | 0.00001 | 85 | |
| Postoperative PCA use | |||||
| Yes | 3 | −1.01 [−1.27, −0.76] | 0.00001 | 43 | 0.002 |
| No | 7 | −1.83 [−2.26, −1.39] | 0.00001 | 86 | |
| DEX dosage | |||||
| ≤1 µg/kg | 7 | −1.82 [−2.23, −1.40] | 0.00001 | 86 | 0.0001 |
| >1 µg/kg | 3 | −0.91 [−1.13, −0.70] | 0.00001 | 0 | |
| Morphine-equivalents 0– 2 4 h postoperatively (mg) | |||||
| Total | 6 | −8.54 [−11.96, −5.13] | 0.00001 | 95 | |
| Allocation concealment | |||||
| Adequate | 2 | −5.98 [−9.48, −2.48] | 0.0008 | 87 | 0.10 |
| Unclear | 4 | −10.02 [−13.37, −6.68] | 0.00001 | 88 | |
| Local anesthetics use | |||||
| Yes | 4 | −9.88 [−13.27, −6.49] | 0.00001 | 91 | 0.13 |
| No | 2 | −6.00 [−9.78, −2.22] | 0.002 | 82 | |
| Postoperative PCA use | |||||
| Yes | 3 | −8.03 [−9.44, −6.62] | 0.00001 | 5 | 0.94 |
| No | 3 | −8.28 [−14.06, −2.50] | 0.005 | 97 | |
| DEX dosage | |||||
| ≤1 µg/kg | 4 | −9.20 [−14.78, −3.62] | 0.001 | 96 | 0.67 |
| >1 µg/kg | 2 | −7.95 [−9.30, −6.61] | 0.00001 | 0 | |
| Time to first analgesic request (min) | |||||
| Total | 12 | 257.57 [209.86, 305.28] | 0.00001 | 93 | |
| Allocation concealment | |||||
| Adequate | 6 | 246.70 [177.68, 315.72] | 0.00001 | 92 | 0.70 |
| Unclear | 6 | 268.03 [185.08, 350.97] | 0.00001 | 94 | |
| Local anesthetics use | |||||
| Yes | 7 | 247.75 [187.67, 307.83] | 0.00001 | 92 | 0.49 |
| No | 5 | 291.85 [182.51, 401.20] | 0.00001 | 95 | |
| Postoperative analgesics | |||||
| Opioids | 6 | 298.74 [202.20, 395.27] | 0.00001 | 94 | 0.28 |
| None opioids | 6 | 234.38 [170.64, 298.12] | 0.00001 | 93 | |
| Postoperative PCA use | |||||
| Yes | 3 | 314.49 [276.22, 352.77] | 0.00001 | 0 | 0.02 |
| No | 9 | 236.52 [186.24, 286.80] | 0.00001 | 93 | |
| DEX dosage | |||||
| ≤1 µg/kg | 8 | 213.20 [169.44, 256.96] | 0.00001 | 89 | 0.0001 |
| >1 µg/kg | 4 | 329.21 [297.12, 361.30] | 0.00001 | 3 | |
| Anesthesia | |||||
| General | 10 | 271.55 [217.40, 325.71] | 0.00001 | 93 | 0.40 |
| Spinal | 2 | 199.07 [40.40, 357.74] | 0.01 | 93 | |
DEX, dexmedetomidine; PCA, patient-controlled analgesia; CI: confidence interval.