Could a Test Predict the Risk of SIDS?
Based on his work over the past 20 years, Schwartz believes that all infants should be screened for long-QT syndrome. He points out that even if the syndrome doesn't lead to SIDS, it can cause death later in childhood.
But Michael Corwin, MD, believes it's inappropriate to perform EKGs on all newborns to screen for long-QT syndrome.
"This new article only provides an example of one case of long-QT in an infant that has a genetic basis," he tells WebMD. "And it does not in any way speak to the key issues, such as what percentage of SIDS cases may be related to long QT, and is it possible to screen infants in order to identify those who are at sufficient risk." Corwin, who was not involved in the study, is an associate professor of pediatrics at Boston University School of Medicine and team leader of data and evaluation at the National SIDS and Infant Death Program Support Center.
Whether the cost of screening every infant outweighs the potential risk is a major issue. Towbin believes it may be better to concentrate on screening infants who are at high risk of long-QT syndrome, such as those with a family history of irregular heartbeats, or those who had a very slow heart rate while still in the womb.
"Only a few babies will actually have this abnormality, and screening a million to find a few may not be as good a focus as screening a few to find a few," says Towbin, who wrote an editorial accompanying Schwartz's 1998 study in The New England Journal of Medicine. "One life lost is one too many, but you still have to do the evaluation in a way that is cost-effective --so you need a combination of what is both medically effective and cost-effective."
But the actual cost of monitoring is very low, Schwartz says. "In Europe it is $15-$20, and it may be a little more expensive in the U.S," he says. "It takes just a few moments and is a simple and non-invasive test. In my opinion, there are very few reasons not to do it. ... If I were a parent, I would not want to run the risk of long-QT syndrome. Even if it is rare, it can kill and does kill."
Also, he notes, several other screening tests are routinely performed, even for disorders for which the risk is extremely low. For example, all infants in the United States are tested for a genetic defect called phenylketonuria, which occurs in one in 100,000 babies. But with SIDS, says Schwartz, we are talking about maybe one in 2,000.
Other researchers have also been working to unravel the mystery of SIDS. One team has found that some infants who die of SIDS are unable to control their breathing while they sleep, and that this pattern may begin as early as the first week of life. These results led other researchers to investigate causes that may have begun before birth. In autopsies of infants who had died of SIDS, researchers found brain stem abnormalities, which probably formed while the baby was still in its mother's womb. These abnormalities may account for the breathing problems noted in some SIDS babies.