Summary of findings for the main comparison. Letrozole with or without adjuncts compared to clomiphene citrate (CC) with or without adjuncts for subfertile women with polycystic ovary syndrome.
| Letrozole with or without adjuncts compared to clomiphene citrate (CC) with or without adjuncts for subfertile women with polycystic ovary syndrome | ||||||
| Patient or population: subfertile women with polycystic ovary syndrome Setting: fertility clinics Intervention: letrozole with or without adjuncts followed by timed intercourse Comparison: CC with or without adjuncts followed by timed intercourse | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | No of participants (studies) | Certainty of the evidence (GRADE) | Comments | |
| Risk with CC with or without adjuncts | Risk with letrozole with or without adjuncts | |||||
| Live birth rate | 214 per 1000 | 314 per 1000 (279 to 352) | OR 1.68 (1.42 to 1.99) | 2954 (13 RCTs) | ⊕⊕⊕⊝ Moderate a | |
| Ovarian hyperstimulation syndrome rate | 5 per 1000 | 5 per 1000 (5 to 5) | RD 0.00 (−0.01 to 0.00) | 2536 (12 RCTs) | ⊕⊕⊕⊕ High | |
| Clinical pregnancy rate | 264 per 1000 | 359 per 1000 (330 to 390) | OR 1.56 (1.37 to 1.78) | 4629 (25 RCTs) | ⊕⊕⊕⊝ Moderate b | |
| Miscarriage rate by pregnancies | 201 per 1000 | 191 per 1000 (150 to 240) | OR 0.94 (0.70 to 1.26) | 1210 (18 RCTs) | ⊕⊕⊕⊕ High | |
| Multiple pregnancy rate | 17 per 1000 | 13 per 1000 (7 to 21) | OR 0.69 (0.41 to 1.16) | 3579 (17 RCTs) | ⊕⊕⊕⊕ High | |
| *The risk in the intervention group (and its 95% confidence interval) is based on the mean risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: Confidence interval; RD: Risk difference: OR: Odds 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 | ||||||
aDowngraded one level for serious risk of bias associated with potential selective reporting: Studies that reported live birth tended to report higher clinical pregnancy rates in the letrozole group than studies that failed to report live birth, suggesting that results might be less favourable to letrozole if all studies reported live birth. bDowngraded one level for serious risk of publication bias: a funnel plot analysis strongly suggests that there might be more publications without a significant effect which were not published.