The Food and Drug Administration (FDA) has issued warnings that common prenatal tests that screen for genetic abnormalities have high rates of false positives, leading some women to abort their children who are actually healthy.
Noninvasive prenatal testing (NIPT) is designed to assess the risk that a baby has a genetic abnormality and cannot definitively confirm or eliminate whether such a condition is present. The FDA notice issued this week advised that is the case, even when manufacturers make claims of “reliability” and “accuracy.”
The FDA expressed its concern that such claims are not supported by “sound scientific evidence.” In some cases involving rare disorders, there may actually be a “high chance” of a false positive.
The FDA stated it has been advised that there have been numerous women who have decided to abort their pregnancy based solely on the results of NIPS testing. The agency said that without a confirming diagnostic test, there “is no way to know” if the child actually had the condition indicated by a NIPS screening.
The FDA said that studies it has reviewed indicate that negative NIPS test results are more than 99.9 percent accurate. However, in cases involving positive results the accuracy is much less reliable. Positive NIPS screening for Down syndrome are only 90 percent accurate.
NIPS tests for microdeletion disorders are much less reliable with “positive predictive values” ranging from 2 percent to 30 percent. As a result, the American College of Obstetricians and Gynecologists does not recommend NIPS screening to detect microdeletion disorders.
The FDA said that it decided to issue the new notice as a result of the increased use of NIPS and concerns about the reliability of the results.
A New York Times report from January stated that microdeletion NIPS tests produce around 85 percent false positives. It cited the case of one woman who aborted her baby after an initial positive result only to learn that a follow-up test had shown her child was actually healthy. Of 14 patients receiving false positives the Times interviewed, eight said they were never advised of the possibility of a false positive result from a NIPS screening.
The Times reported that a number of testing manufacturers failed to properly advise patients of the possibilities of false positives. Many of the doctor and patient brochures advertising the tests never mention the possibility of a false positive at all.