By Lisa Demers
Lisa Demers is a certified genetic counselor working in a prenatal diagnosis program at Dartmouth-Hitchcock in Nashua, NH. She graduated from the Arcadia Genetic Counseling Program in 2003. Lisa has been president of the New England Regional Genetics Group, is a member of the New Hampshire Perinatal Loss Taskforce, and is the proud mother of two little boys who teach her more and more about Star Wars every day.
I feel like it’s time to show some appreciation for the amazing screening test that has truly enhanced the prenatal screening world. Non-invasive prenatal screening (NIPS) has taken our prenatal world by storm and is rapidly infiltrating university hospitals and private practices alike. This is a change (who really likes change?) and it’s fast. Testing has jumped out of the controlled hands of research laboratory scientists and into the lucrative playing field of investor-backed industry. But is this a bad thing?
NIPS has taken traditional screening and made it better. There is no denying that NIPS is a superior screening test. The benefit of NIPS over traditional screening is acknowledged by the rapid approval of coverage by major insurance plans. I applaud Katie Stoll in her eloquent summary of the discrepant positive predictive value (PPV), but I do not think this area of ambiguity should overshadow the benefits of testing. The PPV for a “high risk” (or whatever language the report contains) sample, even if it is 11% (using the data in Katie’s initial post), is about the same as a 1 in 9 risk for trisomy 18 using traditional methods. So is the counseling really very different? “This screening test suggests a very high risk for trisomy 18, diagnostic testing will tell us for sure”.
Our knowledge about how to best utilize this test and interpret the results is an ongoing process. This is completely on par with other technologies. At one point, supernumary rings were identified on karyotype with little way to identify the origin. The argument that we shouldn’t use a technology until we completely understand it is unreasonable. We need large testing numbers to give us these uncertain results so that we can learn from them. Ambiguity with test results is hardly a new concept for us. Genetic counselors deal with this all the time! Our counseling isn’t really changing; it’s just the same uncertainty coming from a different test.
I argue that this test provides much LESS ambiguity since most women are getting reassuring results. The number of women who are screen positive is dramatically decreased. Fewer women being anxious, fewer amnios being considered and performed, and fewer losses of otherwise normal babies. And why wouldn’t an informed patient want the BEST screening test? And why wouldn’t providers want to offer it?
I absolutely acknowledge that not all patients are fully informed about NIPS prior to testing, and I hate to think about the ignorance that providers may pass along to patients. But what genetic counselor hasn’t had a patient arrive at their office with an abnormal screening result thinking that their baby is, in fact, affected? We hear this endlessly. And how long has traditional screening been around? And those results even have a risk estimate listed! Sometimes I like being the hero in these situations “You mean my pregnancy is at a one percent risk for Down syndrome? What a relief!” The misinterpretation of testing results is inevitable. We should not back away from better testing simply because some people do not understand.
While I agree that I would prefer that the commercial labs present their results with some more obvious notation of the limitations of the testing, no report can eliminate ignorance. So perhaps our focus can be a shift to better education. After all, isn’t that we do? We need to talk with providers in our area and help them understand the test more clearly. Review with the nursing staff when a referral is sent to us that the results are screening and not diagnostic. I can tell you that in my own experience, education isn’t always successful because I still have providers who offer universal SMA and Fragile X testing without being able to interpret the results. *Sigh* But these patients are ultimately referred for counseling, and I consider that a success.
Education at the patient level is important too. Group counseling sessions can be an effective way to inform the pregnant population, especially about universal topics like screening. The overwhelming task of education is not unique to prenatal genetic counselors, but to the profession as a whole. Rather than hold back on a test that is truly superior because providers misunderstand it, why don’t we try to tackle the larger issue of provider education?
What I hope is that the consumers of NIPS can work closely with the industry providers to further study the performance of this technology to better understand cell free fetal DNA and its utility in pregnancy screening. Let’s work together in educating providers about the testing and the importance of pre-test counseling. Patients deserve it. Without the cooperation and participation from genetic counselors we risk delaying universal acceptance of NIPS. Let’s all jump aboard and steer this train.