Summary of findings 6. Single‐dose levonorgestrel versus split‐dose levonorgestrel for emergency contraception.
| Single‐dose levonorgestrel versus split‐dose levonorgestrel for emergency contraception | ||||||
| Patient or population: women seeking emergency contraception Setting: multinational (3); family planning clinics Intervention: levonorgestrel, single‐dose Comparison: levonorgestrel, split‐dose | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | № of participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Risk with split‐dose levonorgestrel | Risk with single‐dose levonorgestrel | |||||
| Observed number of pregnancies (all women) | 12 per 1000 | 10 per 1000 (6 to 16) | RR 0.84 (0.53 to 1.33) | 6653 (3 RCTs) | ⊕⊕⊕⊝ Moderate1 | |
| Any side effect | See comment | ‐ | ‐ | ‐ | No study reported this outcome | |
| Specific side effects ‐ nausea | 195 per 1000 | 189 per 1000 (171 to 208) | RR 0.97 (0.88 to 1.07) | 6804 (3 RCTs) | ⊕⊕⊕⊝ Moderate1 | |
| Specific side effects ‐ vomiting | 58 per 1000 | 58 per 1000 (48 to 70) | RR 1.01 (0.83 to 1.22) | 6804 (3 RCTs) | ⊕⊕⊕⊝ Moderate1 | |
| Specific side effects ‐ spotting/bleeding after treatment | 313 per 1000 | 313 per 1000 (282 to 351) | RR 1.00 (0.90 to 1.12) | 2720 (1 RCT) | ⊕⊕⊕⊝ Moderate1 | |
| Menses ‐ early | 299 per 1000 | 200 per 1000 (162 to 245) | RR 0.67 (0.54 to 0.82) | 1118 (1 RCT) | ⊕⊕⊕⊕ High | |
| Menses ‐ delay | 77 per 1000 | 91 per 1000 (74 to 112) | RR 1.18 (0.96 to 1.46) | 3784 (2 RCTs) | ⊕⊕⊝⊝ Low1,2 | |
| *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 quality: we are very confident that the true effect lies close to that of the estimate of the effect Moderate quality: 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 quality: our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect Very low quality: we have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect | ||||||
1We downgraded the quality of evidence by one level for imprecision because the 95% CI overlaps no effect and CI fails to exclude important benefit or important harm. 2We downgraded the quality of evidence by one level for inconsistency because of high heterogeneity in the meta‐analysis.