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Reply to the signatories of the COGEN Consensus Statement

21 March 2016
By Heidi Mertes, Sjoerd Repping & Guido de Wert
Ghent University; Academic Medical Centre, Amsterdam; Maastricht University, the Netherlands
Appeared in BioNews 844

The cosignatories of the COGEN consensus statement attempt to refute our remarks and concerns about the increased use of preimplantation genetic screening (PGS) by presenting the same low-level 'evidence' they continuously use to advocate the widespread adoption of PGS (BioNews 840). In an attempt to once more explain our concerns, there are three serious issues that we will address again.

First, there is no high-level evidence available that demonstrates that PGS will increase the chance for subfertile couples to achieve a live birth. The few trials that have been conducted suffer from serious design, analysis and interpretation issues (1). Yes, randomised controlled trials (RCTs) have been performed, but a randomised trial of low quality is still a low level of evidence despite the fact that patients were randomised. Also, performing a meta-analysis on these flawed RCTs does not magically result in evidence. Unfortunately, many clinics do not bother to wait for evidence, even though they are aware that evidence is lacking. This is emphasised in a survey published alongside the COGEN consensus statement: while 77 percent of all clinics state that PGS is offered in their clinic, 84 percent of those state that more randomised trials are needed to support the use of PGS.

Second, the presentation of the available data is misleading to patients. PGS is being marketed as a technology that increases IVF success rates, but whose success rates are they talking about? It is clear that the reason for couples to attend a fertility clinic is to obtain a healthy liveborn child. And it is this gold-standard success rate in ART (assisted reproductive technology), namely singleton, term-gestation, live-birth rate per cycle initiated, which can never be increased by PGS, simply because PGS does not cure or restore embryos but is solely used as a selection tool. That is what our title referred to. The pro-PGS advocates refuse to make this clear to their patients and instead focus on alternative 'outcomes' such as miscarriages, multiple pregnancy rates and the birth of children with congenital malformations. And even here, high-level evidence is lacking. Patients should never be misled. If a physician repeated the COGEN cosignatories in their reply to us ('unless you use PGS you are more likely to implant aneuploid embryos and implanting aneuploid embryos severely increases your chance of a miscarriage and reduces your chances of having a baby') to a patient, they would be doing just that. Not using PGS does not reduce your chances of having a baby.

Third, we raise concern about the commercialisation of PGS technology. The authors agree that ties with commercial companies exist among the cosignatories but they state that 'this is not a commercially sponsored statement and many of signatories have no links to PGS companies'. Yet it is evident that those who have a financial interest in the product that is under discussion are more likely to highlight the pros than the cons and will not state something that has the potential to negatively affect the sales of that product. Of course, companies are entitled to promote their products. But we strongly feel that when it comes to 'products' in the field of medicine there is only one reason to use those products and that is proven benefit for the patient. Here the application of evidence-based medicine is the moral obligation of all medical professionals (2).

We do not have the illusion that this discussion will change the minds of those that continue to push use of PGS forward (for whatever motivation); beliefs and interests are hard to overcome. But we do hope it will spur further scientific research, more awareness of the issues we raise and drive regulatory bodies to make evidence-based recommendations on the (ab)use of PGS and other reproductive technologies now and in the future.

1) Mastenbroek, S. & Repping, S. (2014). Preimplantation genetic screening: back to the future. Human Reproduction, 29(9), 1846-1850.
|  29 November 2021
2) Dondorp, W., & de Wert, G. (2011). Innovative reproductive technologies: risks and responsibilities. Human Reproduction, 26(7), 1604-1608.
|  29 November 2021
4 April 2016 - by Dr Helen Robertson 
The presence of genetic abnormalities in cells taken from the placenta at the early stages of pregnancy does not necessarily mean that a baby will be born with a genetic disorder, a study in mice suggests....
22 February 2016 - by The signatories of the COGEN Consensus Statement 
It is clear from the reply of Mertes et al in BioNews 835 to the COGEN Consensus Statement on preimplanation genetic screening that some controversy still remains regarding the benefits of PGS...
18 January 2016 - by Heidi Mertes, Sjoerd Repping & Guido de Wert 
Under the auspices of the Virtual Academy of Genetics, COGEN recently issued a 'consensus statement' on preimplantation genetic screening, based on a scientific meeting held in Paris last September...
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