#160 Can we count on Clomiphene for Anovulatory Infertility?
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- Systematic review of Randomized Controlled Trials (RCTs) of anti-oestrogens in PCOS:1
- Three RCTs examined clomiphene (50-250 mg/day, 1-5 cycles) versus placebo, 133 patients.
- Clomiphene:
- Increased pregnancy rate: Clomiphene (20%) versus placebo (3%), Number Needed to Treat (NNT)=6.
- Live births and miscarriages: Not reported.
- Limitations: Small sample size, variable dosing/cycles, high dropout, poor adverse event reporting.
- Systematic review of insulin sensitizing drugs in PCOS (44 RCTs, 3,992 women).2
- Clomiphene versus metformin:
- Subgroup analysis:
- BMI ≥30: Clomiphene superior to metformin for pregnancy NNT=7 and live birth rate NNT=5, (two RCTs, 500 women).
- BMI ≤30: Metformin superior to clomiphene for pregnancy NNT=8, (three RCTs, 349 women) live birth unclear.
- Significant heterogeneity in trials reporting pregnancy and live births.
- Subgroup analysis:
- Adding metformin to clomiphene:
- Improves pregnancy, NNT=13 (11 RCTs).
- No effect birth rates.
- Clomiphene versus metformin:
- Most guidelines recommend clomiphene as first-line therapy in PCOS3,8,9 starting 50mg per day for five days, first dose on day 2-5 of menses. If ovulation is not achieved, dose may be increased to 100mg. Use maximum of six cycles.3,4
- Recent systematic review of aromatase inhibitors in PCOS (26 RCTs, 5,560 women) found letrazole improved live birth over clomiphene (29% vs 18%, NNT = 10). Questions about selective reporting and publication bias limit application.7,8 Letrazole is not approved for infertility in Canada.
- Systematic review of seven RCTs demonstrated no benefit of clomiphene in unexplained infertility.5
- One systematic review reported ovarian hyperstimulation syndrome occurred in 2/1,095 patients treated with clomiphene +/- adjunct therapy.2
- RCT of 626 women reported 6% multiple pregnancy with clomiphene, 0% with metformin, and 3% with the combination of the two.6
- Metformin alone2 improves pregnancy rate versus placebo, NNT=9.