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Cochrane Database of Systematic Reviews

Clomiphene and other antioestrogens for ovulation induction in polycystic ovarian syndrome

Overview of attention for article published in Cochrane database of systematic reviews, December 2016
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Title
Clomiphene and other antioestrogens for ovulation induction in polycystic ovarian syndrome
Published in
Cochrane database of systematic reviews, December 2016
DOI 10.1002/14651858.cd002249.pub5
Pubmed ID
Authors

Julie Brown, Cindy Farquhar

Abstract

Subfertility due to anovulation is a common problem in women. First-line oral treatment is with antioestrogens such as clomiphene citrate, but resistance may be apparent with clomiphene. Alternative and adjunctive treatments have been used including tamoxifen, dexamethasone, and bromocriptine. The effectiveness of these is to be determined. To determine the relative effectiveness of antioestrogen agents including clomiphene alone or in combination with other medical therapies in women with subfertility associated with anovulation, possibly caused by polycystic ovarian syndrome. We conducted a search of the Cochrane Gynaecology and Fertility Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, PsycINFO, and CINAHL (all from inception to August 2016) to identify relevant randomised controlled trials (RCTs). We searched the United Kingdom National Institute for Clinical Excellence (NICE) guidelines and the references of relevant reviews and RCTs. We also searched the clinical trial registries for ongoing trials (inception until August 2016). We considered RCTs comparing oral antioestrogen agents for ovulation induction (alone or in conjunction with medical therapies) in anovulatory subfertility. We excluded insulin-sensitising agents, aromatase inhibitors, and hyperprolactinaemic infertility. Two review authors independently performed data extraction and quality assessment. The primary outcome was live birth; secondary outcomes were pregnancy, ovulation, miscarriage, multiple pregnancy, ovarian hyperstimulation syndrome, and adverse effects. This is a substantive update of a previous review. We identified an additional 13 studies in the 2016 update. The review now includes 28 RCTs (3377 women) and five RCTs awaiting classification. Five of the 28 included trials reported live birth/ongoing pregnancy. Secondary outcomes were poorly reported.The quality of the evidence ranged from low to very low. The primary reasons for downgrading the evidence were imprecision and risk of bias associated with poor reporting. Antioestrogen versus placebo Live birth rate, miscarriage rate, multiple pregnancy rate, and ovarian hyperstimulation syndrome (OHSS)No data were reported for these outcomes. Clinical pregnancy rateClomiphene citrate was associated with an increased chance of a clinical pregnancy compared with placebo, though the size of the benefit was very uncertain (odds ratio (OR) 5.91, 95% confidence interval (CI) 1.77 to 19.68; 3 studies; 133 women; low-quality evidence). If the chance of a clinical pregnancy was 5% in the placebo group, then between 8% and 50% of women would have a clinical pregnancy in the clomiphene group. Clomiphene citrate versus tamoxifen Live birth rateThere was no clear evidence of a difference in the chance of a live birth between the clomiphene citrate and tamoxifen groups (OR 1.24, 95% CI 0.59 to 2.62; 2 studies; 195 women; low-quality evidence). If 20% of women in the tamoxifen group had a live birth, then between 13% and 40% of women in the clomiphene citrate group would have a live birth. Miscarriage rateThere was no clear evidence of a difference in the chance of a miscarriage between the clomiphene citrate and tamoxifen groups (OR 1.81, 95% CI 0.80 to 4.12; 4 studies; 653 women; low-quality evidence). If 3% of women in the tamoxifen group had a miscarriage, then between 2% and 10% in the clomiphene citrate group would have a miscarriage. Clinical pregnancy rateThere was no clear evidence of a difference in the chance of a clinical pregnancy between the clomiphene citrate and tamoxifen groups (OR 1.30, 95% CI 0.92 to 1.85; 5 studies; 757 women; I(2) = 69%; low-quality evidence). If 22% of women in the tamoxifen group had a clinical pregnancy, then between 21% and 35% in the clomiphene citrate group would have a clinical pregnancy. Multiple pregnancy rate There was insufficient evidence of a difference in the chance of a multiple pregnancy between the clomiphene citrate group (OR 2.34, 95% CI 0.34 to 16.04; 3 studies; 567 women; very low-quality evidence). If 0% of women in the tamoxifen group had a multiple pregnancy, then between 0% and 0.5% of women in the clomiphene group would have a multiple pregnancy. OHSSThere were no instances of OHSS in either the clomiphene citrate or the tamoxifen group reported from three studies. Clomiphene citrate with tamoxifen versus tamoxifen alone Clinical pregnancy rateThere was insufficient evidence to determine whether there was a difference between groups (OR 3.32, 95% CI 0.12 to 91.60; 1 study; 20 women; very low-quality evidence). No data were reported for the other outcomes. Other comparisons of interestLimited evidence suggested that compared with a gonadotropin, clomiphene citrate was associated with a reduced chance of a pregnancy, ongoing pregnancy, or live birth, with no clear evidence of a difference in multiple pregnancy rates.The comparison of clomiphene citrate plus medical adjunct versus clomiphene alone was limited by the number of trials reporting the comparison and poor reporting of clinical outcomes relevant to this systematic review and by the number of adjuncts reported (ketoconazole, bromocriptine, dexamethasone, combined oral contraceptive, human chorionic gonadotropin, hormone supplementation). The addition of dexamethasone or combined oral contraceptive suggested a possible benefit in pregnancy outcomes, but findings were very uncertain and further research is required to confirm this.There was limited evidence suggesting that a 10-day regimen of clomiphene citrate improves pregnancy outcomes compared with a 5-day regimen. Data for early versus late regimens of clomiphene citrate were insufficient to be able to make a judgement on differences for pregnancy outcomes. We found evidence suggesting that clomiphene citrate improves the chance of a clinical pregnancy compared with placebo, but may reduce the chance of live birth or ongoing pregnancy when compared with a gonadotropin. Due to low event rates, we advise caution interpreting these data.The comparison of clomiphene citrate plus medical adjunctive versus clomiphene alone was limited by the number of trials reporting the comparison. The evidence was very low quality and no firm conclusions could be drawn, but very limited evidence suggested a benefit from adjunctive dexamethasone or combined oral contraceptives. Low-quality evidence suggested that a 10-day regimen of clomiphene citrate improves pregnancy rates compared with a 5-day regimen, but further research is required.

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Mendeley readers

Mendeley readers

The data shown below were compiled from readership statistics for 293 Mendeley readers of this research output. Click here to see the associated Mendeley record.

Geographical breakdown

Country Count As %
Unknown 293 100%

Demographic breakdown

Readers by professional status Count As %
Student > Bachelor 40 14%
Student > Master 32 11%
Researcher 26 9%
Other 20 7%
Student > Ph. D. Student 20 7%
Other 49 17%
Unknown 106 36%
Readers by discipline Count As %
Medicine and Dentistry 102 35%
Nursing and Health Professions 22 8%
Biochemistry, Genetics and Molecular Biology 9 3%
Pharmacology, Toxicology and Pharmaceutical Science 8 3%
Psychology 5 2%
Other 24 8%
Unknown 123 42%
Attention Score in Context

Attention Score in Context

This research output has an Altmetric Attention Score of 11. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 14 September 2022.
All research outputs
#3,254,625
of 25,457,297 outputs
Outputs from Cochrane database of systematic reviews
#5,877
of 11,499 outputs
Outputs of similar age
#60,219
of 421,685 outputs
Outputs of similar age from Cochrane database of systematic reviews
#131
of 224 outputs
Altmetric has tracked 25,457,297 research outputs across all sources so far. Compared to these this one has done well and is in the 87th percentile: it's in the top 25% of all research outputs ever tracked by Altmetric.
So far Altmetric has tracked 11,499 research outputs from this source. They typically receive a lot more attention than average, with a mean Attention Score of 40.0. This one has gotten more attention than average, scoring higher than 50% of its peers.
Older research outputs will score higher simply because they've had more time to accumulate mentions. To account for age we can compare this Altmetric Attention Score to the 421,685 tracked outputs that were published within six weeks on either side of this one in any source. This one has done well, scoring higher than 85% of its contemporaries.
We're also able to compare this research output to 224 others from the same source and published within six weeks on either side of this one. This one is in the 41st percentile – i.e., 41% of its contemporaries scored the same or lower than it.