Physician society urges better understanding of new prenatal tests

A national society of high-risk obstetricians urged health professionals to be more vigilant about prenatal screening tests in response to a New England Center for Investigative Reporting story that showed that some doctors and patients are placing too much faith in the tests’ results, with several women inadvertently aborting healthy fetuses.

The group, Society for Maternal-Fetal Medicine, on Dec. 17 published a statement on its website underscoring that a new generation of prenatal tests designed to predict the risk a fetus has of a chromosomal abnormality is not diagnostic, meaning any positive result needs to be confirmed. Many companies selling the screens aggressively market the tests, with one company calling them “near-diagnostic,” a term medical experts say means nothing.

“Cell free DNA is not ‘just a simple blood test’ — it is a genetic test with tremendous implications and consequences if misunderstood,” read the statement from the group, made up of physicians and scientists. “Unfortunately, in part because of the high stakes in this competitive market, the tests are being presented as having (greater than) 99 percent accuracy, the same accuracy as is used to describe (true diagnostic tests, such as an amniocentesis).”

The NECIR report, published in the Boston Globe, highlighted limitations of the tests, which first appeared on the market three years ago. The screens detect placental DNA in a mother’s blood and test it for Down syndrome and other more rare genetic conditions. While they perform far better than traditional blood screenings and ultrasounds, false positives and false negatives still occur. In many cases, the chances that a positive test result is correct is less than 50 percent.

The society’s statement also called on the companies to be more forthcoming in helping doctors and patients interpret tests.

“We would call upon the companies reporting these results to be clearer as to the appropriate interpretation of a positive test…,” the statement read.

In addition, the society highlighted the need for genetic counselors to help patients choose and interpret tests. According to the Illinois-based National Society of Genetic Counselors, insurers in many cases will cover the costs of genetic counseling if a doctor or other health care provider recommends it. However, insurance companies have different policies about which tests are covered.

“Genetic counselors and obstetricians want to provide the best possible care to our patients, and that includes ensuring patients receive accurate information about any prenatal screening being offered and what the results could mean to them and their family,” said Jennifer Hoskovec, president of the National Society of Genetic Counselors.

The prenatal screening tests are expected to be discussed at a FDA-sponsored January public meeting about regulation over a broad class of tests, including prenatal screens. The tests are not currently regulated, although the U.S. Food and Drug Administration has proposed a set of rules that will be phased in over nine years once they are approved. Industry is fiercely opposed however, saying they would stifle innovation among other concerns.

In a statement to NECIR, the FDA said once the rules are final they will help patients and health professionals by  “facilitating the development of accurate tests and targeted therapies that can effectively treat diseases.”