Virtually all babies in the U.S. have their heels pricked soon after birth to get a blood sample for genetic testing. These “heel stick” tests identify rare metabolic disorders before they cause irreversible damage, but as more disorders are added to the screening – many states now test for 30 or more – false-positive results are on the rise. In the June issue of Pediatrics, researchers from Children’s Hospital Boston report that false-positive results cause considerable parental stress, even when the baby proves negative on retesting, and that the stress could be alleviated by better education for parents and pediatricians.

Psychologist Susan Waisbren, PhD and Elizabeth Gurian, MS in Children’s Division of Genetics interviewed 173 families who had received false-positive screening results and a comparison group of 67 families with normal newborn screening results.

Although mothers in the false-positive group were interviewed at least six months after their child’s diagnosis had been ruled out, they reported more worry about their child’s future and rated themselves less healthy than mothers in the comparison group. Fifteen percent said their child needed extra parental care, versus 3 percent of mothers in the comparison group. After adjustment for socioeconomic factors, both mothers and fathers in the false-positive group had higher scores on the standardized Parenting Stress Index (PSI); 11 percent of mothers (versus no mothers in the comparison group) scored in the clinical range, in which treatment might be prescribed.

Waisbren and Gurian also found that false-positive tests affected the parent-child relationship: parents in the false-positive group scored more highly on two subscales of the PSI: a Parent-Child Dysfunctional Interaction scale and a Difficult Child scale. (The first asks parents to rate their agreement with statements like “I expected to have closer and warmer feelings for my child, and this bothers me”; the second has statements such as “My child makes more demands on me than most children.”)

Waisbren believes a positive test result can increase expectations of illness even when it is later found to be in error. “We’re not sure why – maybe it feeds into a general nervousness as new parents,” she speculates. “But our results also show that parental stress was greater when families didn’t have adequate information and understanding.”

Two-thirds of parents with false-positive results did not correctly understand why their child was called back for a repeat test, the study found. Mothers who knew the correct reason had reduced stress. (This was not true for fathers, however.)

Other findings:

- Some parents had to wait as long as a month to get the result of the second test, and 26 percent voiced concerns about the length of time before a diagnosis was ruled out.

- Half of all parents in the false-positive group said they hadn’t been told, or didn’t remember being told, that the diagnosis had been ruled out.

- Of these, 22 percent said they were told they wouldn’t be notified unless a problem was found, and 24 percent were required to ask their pediatrician for the test results. “A few parents didn’t even know they’d had a repeat test,” Waisbren says.

- Sixty-one percent of parents felt a need for more information about newborn screening and the test result.

The researchers suggest that improved and better-timed education may reduce parental stress related to newborn screening. “There needs to be a specific communication plan for informing parents at every step,” Gurian says. “Currently, pediatricians are the primary distributors of this information, but some pediatricians don’t feel knowledgeable enough about these rare metabolic disorders to explain a positive test to a parent. It would be good to begin involving obstetricians and to begin educating parents about newborn screening during the prenatal period.”

The study was funded by the Maternal and Child Health Bureau of the U.S. Health Resources and Services Administration and the Ethical, Legal and Social Implications (ELSI) division of the Human Genome Project, National Institutes of Health.

According to the CDC, over 4 million babies born in the U.S. each year undergo screening for biochemical genetic disorders, with severe disorders detected in about 3,000. One recent study suggests that there are at least 12 false-positive results for every true case diagnosed*; another puts the ratio at more than 50:1.**

* Zytkovicz T, et al. Tandem mass spectrometric analysis for amino, organic, and fatty acid disorders in newborn dried blood spots: a two-year summary from the New England newborn screening program. Clin Chem 2001;47:1945-55.

** Kwon C, Farrell PM. The magnitude and challenge of false-positive newborn screening test results. Arch Pediatr Adolesc Med 2000;154:714718.

Children’s Hospital Boston