Non-NIPS tests for Down syndrome are “tarot cards”

Tarot CardsContinuing the examination of Christopher Weaver’s recent report on NIPS in the Wall Street Journal, one quote jumped off the page when I read it. Did you know that screening tests that are not NIPS are as helpful as “tarot cards”?

In his report, headlined “Tough Calls on Prenatal Tests,” Weaver covers the newest form of prenatal testing for Down syndrome, which I have wrote about in several posts categorized as NIPT. Weaver includes the following quote to explain the level of interest in NIPS:

“Women and physicians will do almost anything to reduce their need for invasive testing. That is why it is taking off,” said Lee Shulman, chief of clinical genetics for Northwestern Medicine’s obstetrics unit in Chicago. But while the tests are “a profound improvement over the tarot cards we used to use” to screen for risk, they don’t replace amniocentesis, he said.

Not to knock the predictive value of tarot cards, but that is not how the nuchal translucency-combined test was described when it was introduced.

Nuchal translucency testing had been the subject of investigation for correlating to Down syndrome (and other conditions) since the 1990’s. The National Institutes of Health funded research of the testing with millions of public dollars as part of the (tellingly named) “First And Second Trimester Evaluation of Risk” or FASTER study.

The FASTER study results were published in the New England Journal of Medicine–a publication that typically does not feature tests with the uncertain predictive value of a tarot card reader. Moreover, the FASTER results were one of the main reasons ACOG changed the standards of care in 2007 so that all women were to be offered prenatal testing for Down syndrome.

The reporting on ACOG’s new guidelines in 2007 didn’t say, “ACOG recommends obstetricians send all patients to tarot card readers.” Instead, these were the actual headlines:

Screen all pregnancies for Down syndrome, doctors say, New York Times, January 9, 2007

Doctors should test for Down syndrome, ABC News, May 8, 2007

And, the reporting wasn’t that ACOG had changed the rules of prenatal testing based on some ancient mystic art of foretelling. The New York Times reported “a strong association between the thickening of the neck in this area and the risk of Down syndrome,” not that the thickening of the neck was like The Magician, a trump card in the Tarot deck.

Similarly, ABC News featured Dr. James Goldberg, immediate past chairman of ACOG’s Committee on Genetics, who emphasized: “The important take-home message is this: Better testing is available with higher detection rates and lower false-positive rates.” Dr. Goldberg did not say that the important take-home message was that prenatal screening had the reliability of a card reader in Jackson Square in New Orleans, (where I saw many fortunes told with Tarot cards while attending Tulane Law).

Tarot card readers in Jackson Square, New Orleans. photo credit: Jennifer Zdon, The Times-Picayune archive

Tarot card readers in Jackson Square, New Orleans. photo credit: Jennifer Zdon, The Times-Picayune archive

So, prior to NIPS, the prenatal screening tests had a “strong association” with Down syndrome that justified changing guidelines so that all women should be offered prenatal testing for Down syndrome. But, now, with NIPS, those tests are not much better than reading Tarot cards.

No doubt, the point Dr. Shulman was making was not that nuchal translucency and quad testing were as inaccurate as tarot cards, but to make the comparison that NIPS had much greater accuracy in detecting Down syndrome. Except, the main thrust of Weaver’s article is that it is still unknown how reliable NIPS is given the small sample sizes, the NIPS laboratories’ lack of transparency, and the need for FDA regulation.

Dr. Shulman’s choice of metaphor is still descriptive of non-NIPS tests, in that the number of false positives vastly outnumber the true positives, and therefore are still imprecise predictors of whether a pregnancy is positive for Down syndrome. It is good to see reports like Weaver’s in major publications being skeptical on the promises of NIPS.

But, so far, Weaver’s is the only report in a national publication. Without such reporting, then the impression will be the same as the last time there was a development in prenatal testing: a widely-held belief in the accuracy of the new testing that justifies headlines like “Doctors should test for Down syndrome.”

This is the second in a series examining the WSJ’s report on NIPS. For those who recall the announcement of nuchal translucency testing or have had it performed, what effect would it have had if it had been likened to “tarot cards?”

Comments

  1. I was recommended this web site by my cousin.

    I’m not sure whether this post is written by him as no one else know such detailed about my trouble. You’re wonderful!
    Thanks!

Trackbacks

  1. […] chapter focuses on what are now considered the “old” screening tests: nuchal translucency and quad testing. This is because since October 2011, non-invasive prenatal […]

  2. […] baseline chance for having a child with Down syndrome. But, these tests have been likened to “tarot cards” because they are imprecise, with false positives outweighing the number of pregnancies with […]

Leave a Reply

%d bloggers like this: