Table 1. Effect sizes and subgroup analysis of DEX on postoperative pain intensity and duration.
| Subgroup | Postoperative pain intensity | Postoperative analgesia duration (h) | ||||||
| N* | Effect size# (95% CI) | I2 test (%) | P value | N* | Effect size# (95% CI) | I2 test (%) | P value | |
| All studies | 6 (324) | −1.29 (−1.70, −0.89) | 92 | < 0.00001 | 8 (440) | 6.93 (5.23, 8.62) | 98 | < 0.00001 |
| DEX route | ||||||||
| DEX via epidural route | 1 (50) | −1.23 (−1.58, −0.88) | 0 | < 0.00001 | 1 (36) | 2.00 (0.65, 3.35) | NA | 0.004 |
| DEX via intrathecal route | 2 (114) | −1.36 (−2.13, −0.59) | 93 | 0.0005 | 4 (234) | 4.27 (3.27, 5.26) | 93 | < 0.00001 |
| DEX via caudal route | 3 (160) | −1.01 (−1.53, −0.50) | 92 | 0.0001 | 3 (170) | 10.70 (8.45, 12.95) | 88 | < 0.00001 |
| DEX dose | ||||||||
| ≤5 μg | 2 (114) | −1.36 (−2.13, −0.59) | 93 | 0.0005 | 4 (234) | 4.27 (3.27, 5.26) | 93 | < 0.00001 |
| > 5 μg | 4 (210) | −1.04 (−1.49, −0.59) | 91 | < 0.00001 | 4 (206) | 8.56 (4.42, 12.70) | 98 | < 0.0001 |
| Postoperative time | ||||||||
| 2∼4 h | 4 (220) | −1.10 (−1.80, −0.40) | 91 | 0.002 | — | — | — | — |
| 6∼8 h | 6 (324) | −1.73 (−2.48, −0.97) | 92 | < 0.00001 | — | — | — | — |
| 12 h | 5 (270) | −1.86 (−3.22, −0.51) | 96 | 0.007 | — | — | — | — |
| 24 h | 6 (324) | −0.54 (−1.05, −0.03) | 81 | 0.04 | — | — | — | — |
* Number of trials pooled (total number of subjects).
# Effect size: standardized mean difference for postoperative pain intensity and weighted mean difference for postoperative analgesia duration (h).