Summary of findings 4. Antihistamines compared to placebo for preventing nausea and vomiting in women undergoing regional anaesthesia for caesarean section.
| Antihistamines compared to placebo for preventing nausea and vomiting in women undergoing regional anaesthesia for caesarean section | ||||||
| Patient or population: preventing nausea and vomiting Setting: in women undergoing regional anaesthesia for caesarean section Intervention: antihistamines Comparison: placebo | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | № of participants (studies) | Certainty of the evidence (GRADE) | Comments | |
| Risk with Placebo | Risk with antihistamines | |||||
| Nausea ‐ intraoperative | Study population | RR 0.99 (0.47 to 2.11) | 149 (1 RCT) | ⊕⊝⊝⊝ VERY LOW 1 2 | ||
| 155 per 1000 | 153 per 1000 (73 to 327) | |||||
| Vomiting ‐ intraoperative | Study population | not estimable | 149 (1 RCT) | ⊕⊝⊝⊝ VERY LOW 1 3 |
Only one RCT with no intraoperative vomiting events | |
| 0 per 1000 | 0 per 1000 (0 to 0) | |||||
| Nausea ‐ postoperative | Study population | RR 0.44 (0.30 to 0.64) | 514 (4 RCTs) | ⊕⊕⊝⊝ LOW 4 | ||
| 309 per 1000 | 136 per 1000 (93 to 198) | |||||
| Vomiting ‐ postoperative | Study population | RR 0.48 (0.29 to 0.81) | 333 (3 RCTs) | ⊕⊝⊝⊝ VERY LOW 4 5 | ||
| 189 per 1000 | 91 per 1000 (55 to 153) | |||||
| *The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: Confidence interval; RR: Risk ratio. | ||||||
| GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate; the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited; the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate; the true effect is likely to be substantially different from the estimate of effect. | ||||||
1 Downgrade 2 for risk of bias; only one study with unclear risk of bias across 6 domains and high risk for one domain
2 Downgrade 2 for imprecision: wide CI, only 23 events out of 149 women in a single study.
3 Downgrade 2 for imprecision: there are no events.
4 Downgrade 2 for risk of bias: all data from studies with unclear risk of selection bias
5 Downgrade 1 for imprecision: only 45 events out of 333 women.