Newborn Screening Benefits Greatly Outweigh the Risk of a False-Positive

By Michelle Forman, Senior Specialist, Media, APHL

I’m in a unique position when it comes to the newborn screening work that public health labs perform.  I’m an employee of the Association of Public Health Laboratories, so I review materials and learn about the newborn screening programs in each state on a professional level.  It is my job to understand these programs and to convey how they work to a larger audience.  At the same time, I’m expecting my first baby in a few weeks.  I am now faced with newborn screening from the perspective of a parent – my baby will have her heel pricked and her blood will be sent to the public health lab in my state.  Suddenly my interest in this program is far more personal than it was when I started at APHL.

Yesterday MSNBC.com ran an article about the number of false-positive newborn screening tests around the nation.  The story featured a couple whose baby boy initially tested positive for cystic fibrosis, a chronic disease that affects 30,000 people in the United States.  It took months* for a follow-up test to reveal that it was, indeed, a false-positive.  The baby boy did not have cystic fibrosis.

However, the article focuses on the difficult and stressful time that the family had to wait to learn that good news.  It almost presents the risk of false-positives as opposition to newborn screening.  As a future parent, I can only imagine how scary those months of waiting must have been.  But aren’t a few terrifying days, weeks, or months better than losing your baby to a condition that could’ve been discovered and treated?

As an APHL employee, I have the advantage of understanding the intricacies of the newborn screening programs at public health labs.  I know that there is a risk of a false-positive, but more importantly I know that the labs are working to catch dangerous conditions before they forever alter or even end my baby’s life.  That is invaluable to me.

So why do false-positives exist?  According to Gary Hoffman, Wisconsin State Laboratory of Hygiene Newborn Screening Laboratory Director, there are a number of reasons why false positives exist: assay precision, weight of the baby, specimen collection age, feeding at time of specimen collection, a biological variation, and where the screening laboratory sets analyte cutoffs, to name a few.  “The goal in any screening assay is to minimize false negatives; therefore screening laboratory analyte cutoffs are established at the lowest or highest level possible to detect those babies most likely to have the disorder,” explained Mr. Hoffman.  That is, there are times when false-positives are an unfortunate product of ensuring that the highest number of babies who do in fact have these disorders are detected.

Personally, I’m willing to face the risk of a false-positive.  I would rather have my world shaken for a brief period of time than to lose my baby forever.  Newborn screening saves lives; that’s enough for me.

*While the article does state that it took four months for this parent to receive a definitive diagnosis, that is not the norm.  Most false-positives are resolved within a couple of weeks at the most.