Table 2.
Summary of the findings from pairwise meta-analyses and the level of evidence.
| Outcomes | Studies | Patients | Effect Size (95% CI) or | Heterogeneity, I2 (%) | NNTH (95% CI) | GRADE |
|---|---|---|---|---|---|---|
| Morphine consumption | ||||||
| PACU | 13 | 551 | WMD −1.61 (−2.69, −0.53) | 86% | ⊗⊗⊗ Z | |
| 24 h | 10 | 427 | WMD −1.73 (−2.82, −0.65) | 73% | ⊗⊗⊗ Z | |
| 48 h | 5 | 318 | WMD −3.14 (−10.34, 4.05) | 88% | ⊗⊗⊗ Z | |
| Pain score | ||||||
| PACU | 26 | 1568 | −0.75 (−1.18, −0.32) | 92% | ⊗⊗⊗ Z | |
| 24 h | 11 | 487 | 0.11 (−0.38, 0.60) | 91% | ⊗⊗⊗ Z | |
| 48 h | 5 | 158 | 0.16 (−0.09, 0.41) | 53% | ⊗⊗ | |
| Intraoperative Incidence | ||||||
| Tachycardia | 2 | 125 | RR 0.89 (0.51; 1.54) | 0% | ---- | ⊗ *Y |
| Bradycardia | 8 | 745 | RR 0.86 (0.39; 1.92) | 55% | ---- | ⊗⊗ Z |
| Hypertension | 4 | 505 | RR 1.07 (0.59; 1.93) | 56% | ---- | ⊗⊗ YZ |
| Hypotension | 10 | 845 | RR 0.92 (0.79; 1.08) | 46% | ---- | ⊗⊗⊗ |
| Postoperative Incidence | ||||||
| Tachycardia | 0 | 0 | Not estimable | ---- | ---- | |
| Bradycardia | 5 | 310 | RR 1.65 (0.67; 4.08) | 0% | ---- | ⊗⊗ * |
| Hypertension | 0 | 0 | Not estimable | ---- | ---- | |
| Hypotension | 3 | 200 | RR 1.11 (0.21; 5.76) | 45% | ---- | ⊗⊗⊗ *Y |
| Nausea, PACU | 20 | 1521 | RR 0.46 (0.38; 0.56) | 9% | 3 (3; 4) | ⊗⊗⊗⊗ |
| Nausea, H24 | 6 | 450 | RR 0.55 (0.32; 0.95) | 71% | 2 (2; 4) | ⊗⊗⊗ Z |
| Vomiting, PACU | 12 | 788 | RR 0.34 (0.21; 0.56) | 16% | 9 (8; 13) | ⊗⊗⊗⊗ |
| Shivering | 9 | 581 | RR 0.48 (0.33; 0.70) | 12% | 6 (5; 10) | ⊗⊗⊗ |
| Respiratory depression | 5 | 557 | RR 0.51 (0.07; 3.63) | 87% | ---- | ⊗⊗ Z* |
| Cognitive dysfunction | 1 | 308 | RR 5.06 (0.25; 105) | --- | ---- | ---- |
| Sedation | 6 | 336 | SMD −0.81 (−1.05, −0.58) | 8% | ||
| Serious adverse events | ||||||
| Requiring drug administration | 8 | 691 | RR 1.23 (0.71; 2.15) | 49% | ---- | ⊗⊗⊗ |
| Reported as SAE | 3 | 417 | RR 1.47 (0.87; 2.48) | 84% | ---- | ⊗⊗⊗ *YZ |
CI, confidence interval; GRADE, Grading of Recommendations Assessment, Development and Evaluation; NNTH, number needed to treat for an additional harmful outcome calculated only for statistically significant results; RR, risk ratio. The level of evidence was assessed by the GRADE method. ⊗⊗⊗⊗ (High quality): we are very confident that the true effect is close to the estimated effect. ⊗⊗⊗ (Moderate quality): we are moderately confident in the effect estimate; the true effect is likely to be close to the estimated effect, but there is a possibility that it is substantially different. ⊗⊗ (Low quality): our confidence in the effect estimate is limited; the true effect may be substantially different from the estimated effect. ⊗ (Very low quality): we have very little confidence in the effect estimate; the true effect is likely to be substantially different from the estimated effect. * Downgraded for imprecision: optimal information size not reached. Y Downgraded for insufficient data quality. Z Downgraded for inconsistency (I2 > 50%).