A new generation of prenatal screening tests that detects the risk of chromosomal irregularities like Down syndrome offers pregnant women important information. But some patients - and doctors - are not interpreting the results of these new blood screens, known as cell-free DNA, correctly.
In a recent investigation, NECIR found that misinterpreted results prompted some women to abort healthy fetuses. They thought a “positive" test result meant their fetus almost certainly had a chromosomal irregularity. The reality is a positive test result can be wrong, in some cases, more than 50 percent of the time.
Now, Quest Diagnostics, one of nation’s largest diagnostic testing companies, is funding a nationwide campaign by the Perinatal Quality Foundation — a national non-profit dedicated to improving obstetrical car — to raise awareness of cell-free DNA tests. The grant amount is undisclosed.
Quest has been on the forefront of the issue and published a study in 2014 that highlighted how often “positive" results can be wrong. It unveiled its own prenatal test in May called QNatal Advanced. In contrast to marketing materials provided by some other prenatal testing companies, Quest strongly emphasizes that QNatal is a screening only.
NECIR recently corresponded with Dr. Douglas S. Rabin, medical director of women's health at Quest Diagnostics, and Dr. Mary Norton, Perinatal Quality Foundation president and professor and vice chair for clinical and translational genetics at the University of California in San Francisco. Below are edited responses.
Why are you embarking on this campaign?
Norton: The pace of diagnostic innovation has largely outpaced the knowledge of women and health care providers about how to use and interpret these new tests, including confusion about differences between screening and diagnostic tests; the circumstances under which genetic counseling should be considered; and perhaps most importantly, interpretation of test results.
Dr. Mary Norton is professor and vice chair for clinical and translational genetics at the University of California in San Francisco.
How will you educate consumers and health professionals?
Norton: The campaign includes an educational program and a patient registry. The educational campaign will include a website to inform patients and deliver clear information about the types of prenatal screenings and diagnostic tests, their strengths and limitations, test results interpretation, and actions to consider based on results. It will also educate health care providers about the circumstances under which they should consider referring a woman to a genetic counselor to better understand her risks or test results.
Rabin: The patient registry is a critical part of this program. There are about 4 million live births in the United States every year, and roughly one-fourth of these may be appropriate for this new blood screening. But these screening tests are very new, so little is known about how well they perform in very large populations where the risk of fetal chromosomal problems is low. The patient registry will provide new insights to help close this gap.
Dr. Douglas S. Rabin is medical director of women's health at Quest Diagnostics.
What is the most important piece of information pregnant women should know about these tests?
Rabin: These tests are not diagnostic, meaning they can’t tell if a fetus definitely has a chromosomal condition. Furthermore, in low-risk women in whom the chance of finding a chromosomal issue is very small, there is a chance a positive test will turn out to be a false positive.
The American Congress of Obstetrics and Gynecologists (ACOG) supports the use of these screening tests primarily in high-risk women, which includes those 35 years of age or older or who have a personal or family history, among other factors. But the American Congress also recommends that a positive screen be followed up with a diagnostic test, such as amniocentesis or CVS. This is a very important fact that may not be well understood by all patients and providers.
Quest Diagnostics is adopting the phrase 'noninvasive prenatal screening' to describe QNatal Advanced, as the phrase “noninvasive prenatal test” may inappropriately connote a diagnostic test.
Why are the tests helpful?
Norton: Since the 1960s, pregnant women have been offered the option of screening for these types of chromosomal conditions, but these screens can have false positives that can cause undo worry and require some women to get diagnostic testing with amniocentesis or chorionic villus sampling (CVS). That diagnostic testing carries a small risk of miscarriage, and some minor discomfort.
Cell-free DNA screening has fewer false positives and, if the test is negative, may help more women avoid an amnio or CVS. Of course, any positive screening requires confirmatory diagnostic testing.
Why isn't there a registry already to report results of confirmatory results?
Rabin: Part of it is because this field is so new, so there hasn’t been time to mobilize this kind of effort. In addition, there are certain privacy and consent issues involved in developing registries. We believe the Perinatal Quality Foundation's patient registry — which, when reported, will not have identifying information — is the right idea because it will allow collection of health information, such as results of screening and diagnostic tests and post-partum outcomes, from a large number of women. This is critical research for determining the false positive and negative rates of these screening tests.
What do you hope the result will be of this campaign?
Norton: Our vision is to ensure that every woman and health care provider responsible for obstetrical health in the United States has access to clear, accurate, and unbiased educational resources needed to make informed decisions regarding prenatal testing. Empowered with clear information, women, working with their health care providers, will be better positioned to make decisions regarding their pregnancies, based on their personal risk factors, and consistent with their values, preferences and beliefs.