Outcome | Studies (n) | Patients (n) | Absolute risk (per 1000) | Quality | Comments | ||||
Control | Intervention | OR (95% CI) | Control risk | Estimated Risk of intervention (95% CI) | Risk difference (95% CI) | ||||
HC efficacy | |||||||||
Ovarian quiescence within 7 days | 1 RCT (n = 46) (Cameron et al., 2015)11 | 14/37 | 17/39 | 1.27 (0.51–3.18) | 910 | 928 (837–970) | 28 more effective (73 fewer to 60 more) | Moderate to low | Wide CI reduces certainty of absolute risk |
Cervical mucus blockage within 2 days | 1 RCT (n = 58 cycles) (Brache et al., 2015)10 | 16/29 | 14/29 | 0.76 (0.27–2.13) | 910 | 885 (732–956) | 25 fewer effective (178 fewer to 46 more) | Moderate to low | Wide CI reduces certainty of absolute risk |
EC efficacy | |||||||||
Prevention of ovulation within 5 days | 1 RCT (n = 58 cycles) (Brache et al., 2015) | 28/29 | 16/29 | 0.04 (0.01–0.37) | 987 | 770 (287–965) | 217 fewer effective (20 fewer to 700 fewer) | Moderate to low | Wide CI reduces certainty of absolute risk |
Side effects | |||||||||
Any | 1 RCT (n = 76) (Cameron et al., 2015)11 | 23/37 (From authors) | 26/39 (From authors) | 1.22 (0.48–3.12) | 530 | 579 (349–779) | 49 more experienced side effects (181 fewer to 200 more) | Moderate | Wide CI reduces certainty of absolute risk |
Unscheduled bleeding | 1 RCT (n = 76) (Cameron et al., 2015)11 | 8/37 | 5/39 | 0.53 (0.16–1.81) | 36 | 20 (6–63) | 16 fewer experienced unscheduled bleeding (30 fewer to 27 more) | Moderate | Wide CI reduces certainty of absolute risk |
Ongoing contraceptive use | |||||||||
Short-term (6–8 weeks) | 1 RCT (n = 70) (Michie et al., 2014)12 | 5/31 | 22/39 | 6.73 (2.14–21.20) | 430 | 835 (617–941) | 405 more on contraception at 6 months (187 to 511 more) | Low | Wide CI reduces certainty of absolute risk |
CI, confidence interval; EC, emergency contraception; HC, hormonal contraception; OR, odds ratio; RCT, randomised controlled trial.