More research presented at the 2014 American College of Medical Genetics & Genomics conference. A common theme emerges: non-invasive prenatal screening (NIPS) isn’t what it’s been promised to be, and patients are misunderstanding it.
Poster 397: genetic counseling insights from when NIPS indicated a chromosome condition, but diagnostic testing did not agree. The authors’ conclusion:
These cases emphasize the importance of complete pretest genetic counseling and the appropriate use of NIPT. They also reveal significant gaps and evolving understanding of all factors that affect NIPT results and emphasize the importance of confirmation via invasive testing with karyotype and chromosomal microarray.
Complete pretest counseling. Gaps in understanding. Importance of confirming NIPS through diagnostic testing. Hmmm. These have been recognized by professional statements for two years, and yet the gaps still persist.
Poster 399: the experience of women and genetic counselors with chromosomal microarray testing. Here is a finding and a conclusion:
Over 75% of both groups agreed it is important to discuss pregnancy termination as an option … . Women and genetic counselors agree that resources need to be available to women receiving positive results. As prenatal genomic testing increases, guidelines for counseling and results reporting, as well as resources for women receiving positive results will be needed.
Continuing the way prenatal genetic testing has always been administered: first, offer the testing, then develop the resources women need when receiving positive results. Given that order and gap in information, is it any wonder women have described microarray testing as providing “toxic” knowledge.
Poster 411: Clinicians share their opinions about NIPS:
- “Providers were largely positive about the ability of cffDNA [sic] testing to provide patients with near-diagnostic information and its potential to reduce the need for invasive testing.”
- “However, many providers expressed concern that patients may overestimate the test’s power, highlighting the need for genetic counseling services and improvements in the technology’s sensitivity and specificity.”
- “Finally, several providers voiced concerns that community-based providers lack adequate information and resources, including access to genetic counseling services, to accurately convey the risks and benefits of cffDNA [sic] testing, thereby reinforcing patients’ misconceptions.”
Um, see the posters immediately above.
Poster 421: Higher false positives for Trisomy 18 from NIPS results in change in clinical practice for informed consent:
Companies that provide NIPT promote detection rates as high as 99% for trisomies 21, 18, and 13, with false positive rates at 1% or less. … Our clinic’s experience[:] … 44% (4/9) of our cases where high risk for trisomy 18 was indicated were due to confirmed or suspected confined placental mosaicism. This number is very different than most patients’ and providers’ understanding that a screen positive trisomy 18 result indicates a greater than 99% chance for an affected fetus. … Taking into account these experiences, our clinic has implemented changes in the way we counsel patients[:]
- We now emphasize that NIPT is evaluating placental DNA, as opposed to true fetal DNA, and review the potential sources of “false” positive results, including confined placental mosaicism.
- For those whose results indicate a high chance for trisomy 18, we now also strongly encourage amniocentesis over chorionic villus sampling (CVS), especially in cases where ultrasound at time of CVS is normal.
We feel that these changes are vital to the informed consent process and will likely lead to decreases in patient anxiety, unnecessary invasive testing, and unintended terminations of chromosomally normal fetuses.
Do you see a theme in these findings? The prevalence of misunderstanding based on misconceptions–often prompted by the marketing of NIPS labs–about the accuracy of NIPS; the need for counseling on these limitations; the lack of resources needed to counsel patients; and the absolute need to confirm through diagnostic testing “before decisions are made about irrevocable clinical intervention.“
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