Over at the blog for the Prenatal Information Research Consortium (PIRC), I have a post summarizing an article on the impact NIPS is having on clinical practice. You can read the whole post here.
My PIRC post summarizes what the authors of the article found significant:
- decreasing referrals for genetic counseling
- plummeting diagnostic tests, and
- increased risk for misdiagnoses due to NIPS not identifying almost a third of the genetic conditions present in the pregnancies during the study period (2010-2013).
For you visual learners, here’s the bar graph demonstrating the second point of plummeting diagnostic procedures:
The numbers are hard to read, but essentially the number of CVS and amnio tests performed in 2013 are half as many as in 2010. As covered at this post, as practitioners get less experience sticking a needle into a woman’s womb, the risk of miscarriage will rise.
Here’s the table from the article showing how 1/3 of all genetic conditions would not have been identified by NIPS:
Seeing that a 101 conditions would not have been identified by NIPS gives a different appreciation than simply reading NIPS would not have identified a third of the pregnancies with a genetic condition.
If those hundred-and-one expectant mothers had just had NIPS testing, they would have received a screen-negative, a result commonly (and mistakenly) said to be “99% accurate.” They would not have had diagnostic testing and then learned at birth of their child’s condition (or not at all if the pregnancy miscarried since several of the conditions were trisomies of even larger chromosomes).
While the PIRC post covers what the authors of the report found significant, there were some other references in the report that I thought worth sharing with you:
- NIPS has already gone mainstream: “A survey of obstetricians, both academic and private practice based, predicted that they would offer NIP[S] to high-risk (86.1%) and average-risk women (76.2%) within 12 months.”
- NIPS remains a screening test, with false positives and false negatives: “In a recent report of 109 consecutive screen positive NIP[S] cases that were followed with diagnostic testing, the true positive rates (positive predictive values) for trisomy 21, 18, 13, and sex chromosome aneuploidy were 93%, 64%, 44%, and 38% respectively.” See: NIPS is NOT “99% accurate,” not even for Down syndrome, and especially not for any other genetic condition.
But here’s the reference that stopped me cold:
A recent analysis of cost effectiveness … compared the use of NIP[S] as a diagnostic versus a screening test. The authors found that the use of NIP[S] as a replacement for invasive genetic testing solely for trisomy 21 would lead to 3 more Down syndrome babies born and 2432 more elective terminations, compared with its use as a screening tool. In addition, there would be an almost 100 fold increased risk of terminating an unaffected fetus compared to the risk of loss due to invasive genetic testing.
(emphasis added). From the actual report, that “100 fold increased risk” means 2,424 terminations of unaffected fetuses–essentially the same number of babies with Down syndrome that would be selectively terminated following an NIPS result because the NIPS result would be a false-positive.
And, remember, this was a cost-effectiveness study–a study to determine if NIPS would be “cost-effective” as a diagnostic test. The authors concluded that it would still be cost-effective because it resulted in 2,432 more selective abortions of children with Down syndrome and even though almost that same number of affected fetuses would also be aborted. (The authors ultimately recommended against using NIPS as a diagnostic test, instead recommending confirmatory diagnostic testing, because diagnostic testing leads to “far fewer losses of normal pregnancies.”).
NIPS is being pushed to be offered to every woman and it remains commonly misunderstood as “99% accurate.”
And researchers say it is cost-effective precisely because it will lead to thousands more selective abortions of children with Down syndrome (and even thousands more abortions of children without Down syndrome).