No, that study didn’t find ‘the cause of SIDS.’ Experts explain.
no, that study didn’t find ‘the cause of sids.’ experts

No, that study didn’t find ‘the cause of SIDS.’ Experts explain.


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The news quickly went viral: “THEY FOUND THE CAUSE OF SIDS,” read one sample tweet, one of countless celebratory posts from parents ecstatic over a new study out of Australia. Multiple news sites asserted that the study found a “cause” of sudden infant death syndrome: a biochemical marker that could help identify babies at risk of death.

And why wouldn’t people celebrate? SIDS takes the lives of more than 1,000 babies in the United States each year. That number is significantly lower than it used to be — after a successful public health campaign in the 1990s to encourage parents to put babies to sleep on their backs, SIDS deaths dropped in half — but the death of each baby is shattering, and fear of a sleeping baby never waking up haunts many new parents.

But physician-scientists who have devoted their careers to studying SIDS say the study’s findings are, perhaps understandably, being overblown by people desperate for good news on infant deaths.

“It’s really preliminary,” said Richard Goldstein, MD, associate professor of pediatrics at Harvard Medical School and director of Robert’s Program on Sudden Unexpected Death at Boston Children’s Hospital. “I know some of these researchers. I think it’s good research, but it’s preliminary.”

The study in question, published May 6 in the journal EBioMedicine, was fairly straightforward. Carmel Harrington, a sleep medicine specialist at the Children’s Hospital in Westmead, Australia, tested for levels of the enzyme butyrylcholinesterase in the blood. She and two co-authors thought the enzyme might play a role in SIDS. Sure enough, in dried blood spots that had been taken in the first day or two of life, they found that in 67 infants who later died of SIDS, levels of the enzyme were on average only 73 percent as high as in children who died of other causes.

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The finding makes sense because the enzyme plays an important role in regulating the autonomic nervous system, which controls breathing, heart rate and other basic bodily functions. Infants who die of SIDS are believed to have a dysfunctional autonomous nervous system: When their blood-oxygen level dips during sleep, they remain still, rather than gasping, crying, arching their backs and otherwise making sure they get enough air.

But the study was small, and the finding on low butyrylcholinesterase levels in SIDS was the first time such an observation has been made. Doctors say, therefore, that it has to be replicated in a larger group before they will take it seriously.

Additionally, researchers say, while the lower level of the enzyme in SIDS infants was statistically significant by one measure, it was not significant by another, more common statistical test, so the association could be due purely to chance.

“I would love for this to be true,” said Jose Javier Otero, MD, PhD, associate professor and director of neuropathology at Ohio State University’s College of Medicine, where he researches potential biomarkers for SIDS. “It’s what everybody would like to have: something simple you can test in the blood. That’s why it’s exciting. But whether or not it’s true is very much up in the air.”

Another problem with the study, both doctors said, is that it includes no information on the birth weight of the infants, or on the mothers’ age, blood pressure or use of alcohol, tobacco or drugs — all key risk factors for SIDS.

“One of the biggest predictors of SIDS risk is the birth weight of the baby,” Otero said. “Could the level of this enzyme just be reflecting whether the infant was born with a very low birth weight?”

Given the preliminary findings of the Australian study, how did it generate such excitement among the public? That could be attributed to a news release posted online on May 7 by the Sydney Children’s Hospitals Network, where the researchers are based. The release’s headline stated: “World first breakthrough could prevent SIDS.” Its first sentence went on to say that SIDS “may soon be a thing of the past thanks to a world-first breakthrough.”

In an email to The Post, a press representative of the hospital network explained its news release: “We consider the findings of this study a breakthrough in research because it is the first time researchers have found a marker for SIDS while the infant is still alive. Other biomarkers have been investigated but only on post-mortem samples. It is the fact that this marker is able to be detected prior to death that opens up so much potential for future research.”

A pediatrician who has published over two dozen scientific papers on SIDS said she agrees that finding a possible marker of future SIDS risk when the child is still living is “exciting.”

“Other studies have found factors after the child has died,” said Debra E. Weese-Mayer, professor of pediatrics at Northwestern University Feinberg School of Medicine and director of the Center for Autonomic Medicine in Pediatrics. “Is it a perfect study? No. But if you’re careful not to over-interpret the results, it does add a possible new piece to the puzzle of SIDS.”

She and Goldstein expressed concern, however, that the excessive press coverage surrounding the new paper might lead some parents to lose track of proven risk factors for SIDS that are within their control: ensuring that infants are not exposed to tobacco smoke and that they are put to sleep on their back, with firm bedding and no soft bumpers or pillows.

“I do worry that parents might wrongly take the view that the risk factors are no longer relevant or are less relevant, and that would be more than unfortunate,” Goldstein said.

All three doctors said they found it puzzling that the Australian study received such great attention when other recent SIDS studies have gone mostly ignored. In April, for instance, one study described a “safe sleep calculator” that accurately identified 83 percent of infants before they died of SIDS. Another study published last month, and led by Goldstein, identified new genetic variants that play a role in SIDS.

“The risk calculation paper and the genetics study were both very interesting,” Weese-Mayer said. “But we doctors don’t have any control over the press releases our hospitals send out.”

One concern the doctors had about claims of a “breakthrough” in SIDS research is that it might mislead people into thinking that great strides are being made in the field, Goldstein said. In fact, according to a perspective he co-authored in the New England Journal of Medicine last week, the pace of research stalled decades ago, after the roles of bedding and sleep positioning were identified.

Still, Goldstein said, he’s glad to see any attention to SIDS, even if coverage sometimes gets ahead of the science.

“SIDS is a problem that deserves more attention than it gets,” he said. “It’s the leading cause of death in infants between one month and one year of age, and nearly one in 1,000 U.S. newborns die of it. It’s not a problem that has been solved. It always helps to raise awareness.”

While it’s not a breakthrough, Weese-Mayer said that she nevertheless found the study inspiring. The first author of the paper, she noted, began researching SIDS two decades ago after her infant died of it.

“This was a study driven by the passion of a mother and scientist,” Weese-Mayer said. “And she funded the study through a go-fund-me campaign. It should inspire other scientists to know that they don’t always have to wait on traditional sources of funding. If you’re determined to do a study, you find a way.”

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