Sarah Knapton: Please update your inaccurate, biased report on the NHS offering NIPT to high-risk mums

NHS_2423783bSarah Knapton reports in The Telegraph that Britain’s National Health Service will offer non-invasive prenatal testing (NIPT). The inaccuracies and biases of the report require an update.

Knapton is the Science Editor for the Telegraph. Given her position, it is not presumptuous to expect more accuracy in her report. Below, the inaccuracies are noted and discussed:

Knapton1

Knapton is likely not responsible for captions, but it’s not “baby DNA” that’s being tested. What had been called “non-invasive prenatal testing,” is increasingly being referred to as “cell-free DNA screening” because [1] every other screen is “non-invasive prenatal testing” and [2] “cell-free DNA” (“cfDNA”) is what is screened. Moreover, since the American College of Medical Genetics & Genomics statement was released in 2013, it has been known that the cfDNA screened does not come form the baby but from the placenta. From ACMG’s statement:

ACMG NIPS

(The ACMG refers to NIPT as NIPS to emphasize that it was Non-Invasive Prenatal Screening).

Next, regarding “needles miscarriages,” what miscarriages then would be “needful” or “necessary miscarriages”? Knapton’s next paragraph suggests needless miscarriages are miscarriages of those babies that “would have been born healthy.” This suggests that those babies that have Down syndrome (or another tested condition), if they miscarried, would not have been a “needless miscarriage” since, it is to be inferred by Knapton’s phrasing, those babies would have been aborted anyways.

How loaded with bias is this view: that babies with Down syndrome must be less healthy than another unborn baby with an untested-for condition; that if a baby with Down syndrome is miscarried due to diagnostic testing, then that is not a needless miscarriage; and, that expectant mothers receiving a prenatal diagnosis for Down syndrome would necessarily abort.

Here’s the next section of Knapton’s report:

Knapton2See the first note above regarding the inaccuracy of “DNA belonging to the unborn child” (and see these posts here and here).

Knapton again repeats the line that cfDNA screening is “99 per cent accurate,” which suggests she may not know what cfDNA screening is 99% accurate for versus what a cfDNA screen result means for the mother. By her writing, most lay readers, and more specifically more expectant mothers, will understandably believe that a “screen-positive” cfDNA screen means they have a 99% chance of having a child with Down syndrome. After all, Knapton reports it’s 99% accurate. But, a cfDNA result is almost never 99% accurate for predicting the chances of an unborn child having Down syndrome.

These posts here, here, here, and here  explain the difference between sensitivity and specificity as compared to positive predictive value (PPV), because it’s PPV that actually predicts the chances. (Note, in the first quoted section, the underlined figure of “1 in 150” is the PPV as determined either by the age of the mother or a conventional screen result; it is this “high risk” population to whom the NHS is restricting the offer of cfDNA).

Next: Chitty is correct and accurate in her quote that cfDNA screening offers greater accuracy for screening for Down syndrome. But her next quote offers misleading comfort to expectant moms. Cell-free DNA alone does not offer mothers as much reassurance about the health of their baby as conventional screening because cfDNA screening only tests for a few conditions, missing many other conditions identified by conventional screening.

Lastly, note how throughout Knapton’s column she and those quoted refer to what is being tested: not a fetus, but an unborn child, a baby even. So, let’s dispense with the euphemistic phrasing that prenatal testing gives women and their partners “more information that allows them to make choices about their pregnancy that are best for them.” Let’s be candid about what Chitty and Knapton’s inclusion of that quote is saying:

That prenatal testing allows parents to abort their children tested for Down syndrome.

To The Telegraph’s credit, it published a column by Tim Stanley three days after Knapton’s inaccurate article. Its headline calls a spade a spade:

Stanley headline

Because, as the headline and subheadline further address, expectant parents may receive “more information” by prenatal testing, but as covered at length on this blog, they too often do not receive all of the recommended information about Down syndrome. Knapton’s inaccurate reporting reflects this societal ignorance about a life with Down syndrome. From the last section of her report:

Knapton3

It is an overstatement to say that cfDNA screening can detect “potentially serious consequences” in terms of Down syndrome, just as it is an overstatement to frame the likelihood of “severe” learning difficulties as on par with “mild” when it comes to Down syndrome.

Down syndrome is associated with a variety of co-occurring physical conditions that can accurately be termed “potentially serious,” with heart conditions requiring surgery and gastro-intestinal issues just to name two such conditions. But cfDNA screening does not detect any of these conditions. Cell-free DNA screening only reports probabilities on the number of chromosomes present–it is silent on any structural concerns. Similarly, when crafting their guidelines for delivering a Down syndrome diagnosis, the National Society of Genetic Counselors noted that quoting the range of intellectual disability as “mild to severe” is not as accurate as a range of the more likely incidence of intellectual disability being “mild to moderate.”

Perhaps this public calling out of Knapton will be counter-productive and she will not update her inaccurate, biased report. More likely, she won’t even read this. But, I feel justified in taking this public stand because cfDNA screening is no longer a new technology–it was introduced in October 2011–and, the inaccuracies about what it tests (DNA from the placenta), how accurate it is (not 99% for PPV), and the euphemisms in what it allows for need to be dispensed with and corrected.

But, more importantly is the either ignorant or prejudiced view Knapton voices towards Down syndrome: that babies with Down syndrome are not healthy; are diseased; can have severe intellectual disability as often as mild; and that if a baby with Down syndrome is miscarried due to an invasive diagnostic test that is not as “needless” of a miscarriage as a child without Down syndrome. These and other myths, Stanley ably tries to dispel in his column. But, I think another report that appeared shortly after Knapton’s may be the most effective in challenging the misunderstood view of Down syndrome that her reporting conveys.

CBS news ran a report about Tim Harris closing his restaurant in New Mexico to move to Denver. Here is the far more accurate and compassionate report about individuals with Down syndrome by CBS correspondent Steve Hartman:

Hopefully, Knapton will also view the CBS report and it will inform how she writes about lives with Down syndrome.

I wrote three years ago about the bioethical principles that support the thrust of Knapton’s column: that cfDNA screening can be used to avoid more miscarriages from invasive procedures. That post can be viewed here

Comments

  1. Sarah Knapton is an idiot. She was even banned from breaking an embargo with Nature, so I wouldn’t trust her science reporting. Absolute amateur.

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