GnRH antagonist versus long agonist protocols in IVF: a systematic review and meta-analysis accounting for patient type

BACKGROUND

Most reviews of IVF ovarian stimulation protocols have insufficiently accounted for various patient populations, such as ovulatory women, women with polycystic ovary syndrome (PCOS) or women with poor ovarian response, and have included studies in which the agonist or antagonist was not the only variable between the compared study arms.

OBJECTIVE AND RATIONALE

The aim of the current study was to compare GnRH antagonist protocols versus standard long agonist protocols in couples undergoing IVF or ICSI, while accounting for various patient populations and treatment schedules.

SEARCH METHODS

The Cochrane Menstrual Disorders and Subfertility Review Group specialized register of controlled trials and Pubmed and Embase databases were searched from inception until June 2016. Eligible trials were those that compared GnRH antagonist protocols and standard long GnRH agonist protocols in couples undergoing IVF or ICSI. The primary outcome was ongoing pregnancy rate. Secondary outcomes were: live birth rate, clinical pregnancy rate, number of oocytes retrieved and safety with regard to ovarian hyperstimulation syndrome (OHSS). Separate comparisons were performed for the general IVF population, women with PCOS and women with poor ovarian response. Pre-planned subgroup analyses were performed for various antagonist treatment schedules.

OUTCOMES

We included 50 studies. Of these, 34 studies reported on general IVF patients, 10 studies reported on PCOS patients and 6 studies reported on poor responders. In general IVF patients, ongoing pregnancy rate was significantly lower in the antagonist group compared with the agonist group (RR 0.89, 95% CI 0.82-0.96). In women with PCOS and in women with poor ovarian response, there was no evidence of a difference in ongoing pregnancy between the antagonist and agonist groups (RR 0.97, 95% CI 0.84-1.11 and RR 0.87, 95% CI 0.65-1.17, respectively). Subgroup analyses for various antagonist treatment schedules compared to the long protocol GnRH agonist showed a significantly lower ongoing pregnancy rate when the oral hormonal programming pill (OHP) pretreatment was combined with a flexible protocol (RR 0.74, 95% CI 0.59-0.91) while without OHP, the RR was 0.84, 95% CI 0.71-1.0. Subgroup analysis for the fixed antagonist schedule demonstrated no evidence of a significant difference with or without OHP (RR 0.94, 95% CI 0.79-1.12 and RR 0.94, 95% CI 0.83-1.05, respectively). Antagonists resulted in significantly lower OHSS rates both in the general IVF patients and in women with PCOS (RR 0.63, 95% CI 0.50-0.81 and RR 0.53, 95% CI 0.30-0.95, respectively). No data on OHSS was available from trials in poor responders.

WIDER IMPLICATIONS

In a general IVF population, GnRH antagonists are associated with lower ongoing pregnancy rates when compared to long protocol agonists, but also with lower OHSS rates. Within this population, antagonist treatment prevents one case of OHSS in 40 patients but results in one less ongoing pregnancy out of every 28 women treated. Thus standard use of the long GnRH agonist treatment is perhaps still the approach of choice for prevention of premature luteinization. In couples with PCOS and poor responders, GnRH antagonists do not seem to compromise ongoing pregnancy rates and are associated with less OHSS and therefore could be considered as standard treatment.

Are GnRH antagonists comparable to agonists for use in IVF?

We believe that appropriate comparison of optimal GnRH agonist and antagonist regimens has not been performed yet. Currently available meta-analyses included all comparative studies between GnRH agonists and antagonists performed so far, including less than optimal GnRH antagonist regimens. After critical appraisal of the various studied GnRH antagonist regimens in terms of follicular development and IVF outcome, we postulate that early suppression of endogenous FSH results in optimal follicular development. Additionally, stable and early suppression of LH and progesterone levels during the entire period of stimulation may be an advantage for implantation and pregnancy outcome. In this respect, single dose and particularly flexible protocols seem to be less advantageous. Early FSH and LH suppression can be achieved by early GnRH antagonist administration (stimulation day 1) or by oral contraceptive (OC) pretreatment. More studies comparing long GnRH agonist protocols with 'long' GnRH antagonist protocols, with enough power to identify differences in pregnancy rates, are required before appropriate comparison can be made.

Cetrorelix in an oral contraceptive-pretreated stimulation cycle compared with buserelin in IVF/ICSI patients treated with r-hFSH: a randomized, multicentre, phase IIIb study

BACKGROUND

The aim of this study was to assess the non-inferiority of an oral contraceptive (OC)-pretreated cetrorelix regimen and a buserelin regimen in IVF/ICSI patients treated with r-hFSH in terms of total number of oocytes retrieved.

METHODS

Multicentre, randomized study. One hundred and eighty two patients were randomized to receive cetrorelix with OC pretreatment (n = 91) or to receive buserelin (n = 91). The cetrorelix group started with daily OCs on cycle day 5 and continued for 21-28 days. Cetrorelix (0.25 mg) was given daily from stimulation day 6 up to and including the day of r-hCG administration. The buserelin group started with buserelin (500 microg/day) for at least 10 days until down-regulation was achieved, after which the dose was reduced to daily 200 microg up to and including the day of r-hCG administration. r-hFSH was started in both groups on a Friday, in the cetrorelix group 5 days after the last OC pill intake. Both regimens were followed by a standard IVF or ICSI procedure. The primary efficacy endpoint was the number of oocytes retrieved per patient.

RESULTS

Number of oocytes, cancellation rates, r-hFSH requirements, number of oocyte retrievals during the weekend or public holiday and number of pregnancies were similar in both groups. Both treatment regimens were well tolerated.

CONCLUSIONS

Cetrorelix pretreated with OCs resulted in similar number of oocytes retrieved compared with a long buserelin protocol. Both regimens were well tolerated and allowed scheduling of the oocyte retrieval, with only small number of retrievals falling on a weekend or public holiday.

Basal FSH concentrations as a marker of ovarian ageing are not related to pregnancy outcome in a general population of women over 30 years

BACKGROUND

Previous studies suggest that elevated basal FSH concentrations are related to aneuploid pregnancies. However, there have been no prospective studies evaluating the incidence of aneuploidies in relation to basal FSH concentrations. Since the majority of aneuploid conceptions end in early pregnancy loss or abortion of a recognized pregnancy, these determinants are appropriate intermediate end-points to study aneuploidy.

METHODS

We performed a prospective study in 129 women without a history of subfertility pursuing a spontaneous pregnancy. Basal FSH concentrations were measured during three menstrual cycles. Urinary HCG levels were measured during menstruation for a maximum of six menstrual cycles, to detect early pregnancy loss. We estimated the effect of basal FSH concentrations on pregnancy outcome, taking into account possible confounders.

RESULTS

We observed no significant effect of basal FSH concentrations on the incidence of early pregnancy loss or abortion of clinically recognized pregnancies.

CONCLUSIONS

We conclude that in a population of women without a history of subfertility, pursuing a spontaneous pregnancy, basal FSH concentrations are not related to the incidence of early pregnancy loss or abortions. This prospective study therefore fails to confirm a relationship between signs of decreased ovarian reserve and aneuploid pregnancies.

Gonadotropin-releasing-hormone-receptor antagonists

Pulsatile gonadotropin-releasing hormone (GnRH) stimulates the pituitary secretion of both luteinising hormone (LH) and follicle-stimulating hormone (FSH) and thus controls the hormonal and reproductive function of the gonads. Blockade of GnRH effects may be wanted for a variety of reasons-eg, to prevent untimely luteinisation during assisted reproduction or in the treatment of sex-hormone-dependent disorders. Selective blockade of LH/FSH secretion and subsequent chemical castration have previously been achieved by desensitising the pituitary to continuously administered GnRH or by giving long-acting GnRH agonists. Only recently have GnRH-receptor antagonists, that immediately block GnRH's effects, been developed for clinical use with acceptable pharmacokinetic, safety, and commercial profiles. In assisted reproduction, these compounds seem to be as effective as established therapy but with shorter treatment times, less use of gonadotropic hormones, improved patient acceptance, and fewer follicles and oocytes. All current indications for GnRH-agonist desensitisation may prove to be indications for a GnRH antagonist, including endometriosis, leiomyoma, and breast cancer in women, benign prostatic hypertrophy and prostatic carcinoma in men, and central precocious puberty in children. However, the best clinical evidence so far has been in assisted reproduction and prostate cancer.

Direct ovarian effects and safety aspects of GnRH agonists and antagonists

In in-vitro fertilization programmes, gonadotrophin releasing hormone (GnRH) agonists are now routinely used in order to prevent the undesired pre-ovulatory spontaneous luteinizing hormone surge. The first publications are now appearing in which GnRH antagonists are used with the same purpose. More attention should be addressed to the safety aspects of these drugs. This review aims to summarize studies on direct ovarian effects of GnRH agonists and GnRH antagonists in non-primates and primates with respect to the functional and morphological aspects in-vitro as well as in-vivo. We conclude that there is a wide variety of functional and morphological effects of GnRH analogues on the ovary. The sometimes paradoxical effects indicate that a variety of factors may be involved in the various processes. Those factors are: (i) the type and dose of the analogue, (ii) the different regimens of administration, (iii) ovarian status at the time of exposure, (iv) ovarian cell types in in-vitro systems, (v) hormonal pre-treatment of these cultures, (vi) the type of hormonal stimulation added to the in-vitro culture, (vii) further methodological differences in the experiments and finally (viii) physiological variations in GnRH receptor abundance which depends on species and/or timing in the cycle. With the increasing number of patients using GnRH analogues in assisted reproduction treatments, there will be an increasing number of pregnancies exposed to these drugs. So far, there does not appear to be an increased risk of birth defects or pregnancy wastage in human pregnancies exposed to daily low-dose GnRH agonist therapy in the first weeks of gestation.