Low responders may benefit from undergoing ovarian stimulation with a long GnRH agonist protocol with corifollitropin alfa followed by hMG

OBJECTIVE

To evaluate the outcomes of a long GnRH agonist protocol with corifollitropin alfa followed by hMG in low responders.

METHODS

Retrospective cohort study. Patients with a suboptimal previous ovarian response (<9 oocytes) and a normal ovarian reserve (Poseidon groups 1 and 2) were classified in 1) Group 1 (n=88), submitted to a second cycle with a GnRH antagonist protocol using rFSH/hMG; 2) Group 2 (n=66), submitted to a long GnRH agonist protocol with corifollitropin alfa followed by hMG (named as simplified long protocol). Clinical outcomes were compared between groups and between the first/second cycle of each group.

RESULTS

Clinical outcomes were similar between groups. There were no differences in the number of oocytes [7(5-11.75) versus 7(5-10), p=0.802], clinical pregnancy (19.3% versus 18.2%, p=0.858) and live birth rates (18.2% versus 15.2%, p=0.619). However, baseline characteristics were different, decoding a poor prognosis among women in group 2. Both groups (1 and 2) had significantly higher number of oocytes, pregnancy, and live birth rates in the second cycle. In group 2, there was a higher rate of embryo transfer (56.1% versus 27.3%, p<0.001). In group 1, despite the similar rate of embryo transfer, there was a higher positive hCG (23.9% versus 8.0%, p=0.004).

CONCLUSIONS

Both simplified long protocol and GnRH antagonist protocol are suitable for low responders. The best second cycle clinical outcomes experienced in a population with worse prognosis (group 2) suggests that the simplified long protocol may be a better option, although prospective well-conducted studies must explore this hypothesis.

Trends in 'poor responder' research: lessons learned from RCTs in assisted conception

BACKGROUND

A substantial minority of women undergoing IVF will under-respond to controlled ovarian hyperstimulation. These women-so-called 'poor responders'-suffer persistently reduced success rates after IVF. Currently, no single intervention is unanimously accepted as beneficial in overcoming poor ovarian response (POR). This has been supported by the available research on POR, which consists mainly of randomized controlled trials (RCTs ) with an inherent high-risk of bias. The aim of this review was to critically appraise the available experimental trials on POR and provide guidance towards more useful-less wasteful-future research.

METHODS

A comprehensive review was undertaken of RCTs on 'poor responders' published in the last 15 years. Data on various methodological traits as well as important clinical characteristics were extracted from the included studies and summarized, with a view to identifying deficiencies from which lessons can be learned. Based on this analysis, recommendations were provided for further research in this field of assisted conception.

RESULTS

We selected and analysed 75 RCTs. A valid, 'low-risk' randomization method was reported in three out of four RCTs. An improving trend in reporting concealment of patient allocation was also evident over the 15-year period. In contrast, <1 in 10 RCTs 'blinded' patients and <1 in 5 RCTs 'blinded' staff to the proposed intervention. Only 1 in 10 RCTs 'blinded' ultrasound practitioners to patient allocation, when assessing the outcome of early pregnancy. The majority of trials reported an intention-to-treat analysis for at least one of their outcomes, with an improving trend in the recent years. Substantial variation was noted in the definitions used for 'poor responders', the most popular being 'low ovarian response at previous stimulation'. The preferred cut-off value for defining previous low response has been 'less or equal to three retrieved oocytes'. The most popular tests used for diagnosing diminished ovarian reserve have been antral follicle count and FSH. Although the Bologna criteria for POR were only recently introduced, they are expected to become a popular definition in future 'poor responder' trials. Numerous interventions have been studied on 'poor responders'. Most of these have been applied before/during controlled ovarian hyperstimulation. The antagonist protocol, the microdose flare protocol and the long down-regulation protocol have been among the most popular interventions. The analysis of outcomes revealed a clear improving trend in reporting live birth. In contrast, only 10% of RCTs reported significant improvement in reproductive outcomes among tested interventions. Twelve 'significant' interventions were reported, each supported by a single 'positive' RCT. Finally, trials of higher methodological quality were more likely to have been published in a high-impact journal.

CONCLUSIONS

Overall, the majority of published trials on POR suffer from methodological flaws and are, thus, regarded as being high-risk for bias. The same trials have used a variety of definitions for their poor responders and a variety of interventions for their head-to-head comparisons. Not surprisingly, discrepancies are also evident in the findings of trials comparing similar interventions. Based on the identified deficiencies, this novel type of 'methodology and clinical' review has introduced custom recommendations on how to improve future experimental research in the 'poor responder' population.

Prospective power calculations for the Four Lab study of a multigenerational reproductive/developmental toxicity rodent bioassay using a complex mixture of disinfection by-products in the low-response region

In complex mixture toxicology, there is growing emphasis on testing environmentally representative doses that improve the relevance of results for health risk assessment, but are typically much lower than those used in traditional toxicology studies. Traditional experimental designs with typical sample sizes may have insufficient statistical power to detect effects caused by environmentally relevant doses. Proper study design, with adequate statistical power, is critical to ensuring that experimental results are useful for environmental health risk assessment. Studies with environmentally realistic complex mixtures have practical constraints on sample concentration factor and sample volume as well as the number of animals that can be accommodated. This article describes methodology for calculation of statistical power for non-independent observations for a multigenerational rodent reproductive/developmental bioassay. The use of the methodology is illustrated using the U.S. EPA's Four Lab study in which rodents were exposed to chlorinated water concentrates containing complex mixtures of drinking water disinfection by-products. Possible experimental designs included two single-block designs and a two-block design. Considering the possible study designs and constraints, a design of two blocks of 100 females with a 40:60 ratio of control:treated animals and a significance level of 0.05 yielded maximum prospective power (~90%) to detect pup weight decreases, while providing the most power to detect increased prenatal loss.