20 November 2017
Assistant Director, Nuffield Council on BioethicsAppeared in BioNews 927
The new 'reflex' method of antenatal screening for Down's, Edwards' and Patau's syndromes was described last week as a 'transformational advance'. It might be cheaper than other approaches, but it could come at the cost of informed choice for pregnant women and couples.
The authors of the study published in Genetics in Medicine compared their 'reflex' model to the screening test currently offered to women on the NHS – the combined test. They stated that 'no other method of prenatal screening for these disorders has such a high detection rate for such a low false-positive rate'. Further benefits of the reflex model were suggested to be that women would be less likely to become acutely anxious, and cost-savings due to a reduced need for diagnostic and counselling.(1)
The Nuffield Council on Bioethics published a report on the ethics of non-invasive prenatal testing (NIPT) earlier this year.(2) NIPT is a technique for analysing cell-free DNA from the placenta circulating in pregnant women's blood. My involvement with this project leads me to believe that the reflex study, and much of the resulting media coverage, has ignored a swathe of research and public debate that has guided policymakers down a path that is subtly but importantly different to the one advocated by the reflex model.
The reflex model is not a new prenatal test but a different way of offering NIPT. It involves taking the woman's blood at the initial consultation and automatically sending this to be analysed using NIPT if the woman is found to have at least a 1 in 800 chance of having a fetus with Down's, Edwards' or Patau's syndrome following the combined test. The woman is not informed of the result of the combined test before the NIPT stage. The study press release states the reflex model is 'far more accurate and safer' than existing tests – safer in that it results in fewer women having confirmatory diagnostic tests, such as amniocentesis, which carry a small risk of miscarriage.
However, the reflex study is just one of many to show that NIPT is more accurate and leads to fewer false positive results than the combined test. For example, in the NIHR-funded RAPID study that involved 30,000 screened women across eight NHS hospitals, NIPT identified all fetuses with Down's syndrome among women who opted for the test, and resulted in few false positives.(3)
More concerning is the impression that reproductive choice was not given high priority in the reflex study. One of the central recommendations of the Nuffield Council's report is that pregnant women and couples should have access to NIPT but only within an environment that enables them to make autonomous, informed choices. Patient groups and others who contributed to the consultation activities for the Council's report raised concerns that the reflex model may not provide women with enough opportunity for discussion and reflection. As a result, it could compromise their ability to give informed consent to NIPT.(2)
Reflex screening might support informed choice if women and couples were given the opportunity to have an extended discussion with a specially trained professional at the beginning of the screening process. This would allow them to discuss the possibility of their blood sample being sent for NIPT analysis, the implications of different results, the choices that testing may lead to, and what it is like to have a child with the condition being tested for. However, the only reference to the provision of information or support in the study is that women who opted for screening 'received a leaflet describing the reflex DNA approach'.
One of the reasons given by the authors for not returning the combined test results to women before the NIPT stage was to reduce unnecessary anxiety: 'imparting potentially distressing information when this can be completely avoided is self-evidently of benefit'. I would argue that nothing is self-evident in this complicated area of medicine.
Their approach may be better for those women who have false positive results, but it might not be as good for women who have 'true positive' results. We do not currently know. Also, this approach will not necessarily reduce anxiety in the long run and, even if it does, this does not mean women and couples should be denied the opportunity to consider their options in light of a high-chance combined test result. In addition, their approach does not fit with the recent shift in medical practice away from what a reasonable doctor would tell the patient, to what a reasonable patient would want to know.
The reflex model also appears to disregard recent public debate on NIPT for Down's syndrome. Concerns have been reignited that the aim of prenatal screening is to 'screen out' Down's syndrome rather than promote reproductive choice for women. Hence, one thing that almost all contributors to the debate agree on is that NIPT is only ethical if women and couples are given up-to-date, balanced and non-directive information and support during the screening process to enable them to make properly informed choices.
This message has reached policymakers. NIPT will be offered as part of the NHS Fetal Anomaly Screening Programme across England and Wales from 2018. In this model, pregnant women who are found to have at least a 1 in 150 chance of their fetus having Down's, Edwards' or Patau's syndromes after having the combined test will be given the opportunity to discuss with a specially trained healthcare professional whether they would like to have NIPT, diagnostic testing or no further testing. Public Health England has been developing a programme of training with the input of the Down's, Edwards' and Patau's syndrome communities in preparation for the roll-out next year.
In light of all this, it seems surprising that the researchers responsible for the reflex study are now 'approaching other hospitals in the UK to see if they would be interested in adopting the new test', according to the study press release. Removing an opportunity to give information and choice to pregnant women and couples in the screening process is a move in the opposite direction to that which policy and public attitudes are currently travelling.