San Francisco -- Stanford University researchers have developed
a new method for predicting health problems in premature babies
that they say is much more reliable than the standard Apgar score
used to evaluate newborns' health.
The new method, which the researchers have named the PhysiScore
, rates infants' health based on vital signs taken at birth and
over the first three hours of life. In a study of 138 infants at
Packard Children's Hospital , the score was able to predict a
baby's chances of developing a serious illness with an accuracy of
91 percent to 98 percent.
The Apgar score has been favored for more than 50 years because
it's simple and fast -- in the seconds after birth, doctors
consider five health factors, such as how well an infant cries and
how much he or she squirms about, and they assign a score.
But the Apgar test is more subjective. The PhysiScore relies on
hard data, including a newborn's weight, heart rate and respiratory
weight. At the same time, the PhysiScore is fairly easy to
determine because it takes data that's already being collected and
uses a computer algorithm to spit out a health score.
"At the three-hour point, out pops a prediction number," said
Dr. Anna Penn , a neonatologist at Packard Children's Hospital and
a co-author of the study, which was published this month the
journal Science Translational Medicine . "What this will likely be
is one piece of information used among several others. It's
something that can be valuable for decision-making."
The Apgar score is useful to doctors for determining the broad
treatment course of a baby born prematurely, or with other health
problems. Babies born with a low Apgar score will likely be taken
to a neonatal intensive care unit, or may even be transferred to a
hospital able to provide more specialized care.
But in the Stanford study, the new method was far more accurate.
For example, the Apgar score could predict whether a baby would
develop a dangerous infection with 74 percent accuracy; the
PhysiScore could make the same prediction with 97 percent accuracy.
Part of the reason for the increased accuracy may be the new
scoring system's use of a computer algorithm to assess raw
electronic data.
The PhysiScore uses vital signs like a newborn's heart rate and
oxygen saturation, as well as how those vital signs change over
time. These are all numbers that have long been available to
doctors, but it's been impossible for medical staff to constantly
process all of the information and evaluate every infant based on
the data collected.
In other words, for years hospitals have been collecting useful
medical information on infants, but not taking full advantage of
it, said Daphne Koller , a computer science professor in the
Stanford University School of Engineering, who helped design the
new scoring system.
"Doctors look at the data on a monitor, and they look for
certain cues like the respiratory is low, but largely that data is
thrown away," Koller said. "What we were struck by was the
richness of information that's already available and how much you
can extract from it."
In fact, researchers already are thinking about how similar
scoring methods could be applied to other patients -- people who
have had heart attacks, for example, Penn said. With more hospital
keeping electronic medical records, there is a large amount of data
automatically collected on patients, and much of it isn't being put
to use, she said.
It remains to be seen whether the PhysiScore will be reliable
when applied to larger groups of infants. The babies in the
Stanford study were born premature -- six weeks or more short of
full-term, 40-week pregnancy -- and weighed less than 4 pounds, 6.5
ounces.
The new method may not be as accurate when applied to babies
born closer to 40 weeks of gestation. Or, the researchers said,
there may be something about the babies cared for at Packard
Children's Hospital that sets them apart from other infants and
would impact their PhysiScore. Researchers said they plan to
conduct further studies of larger groups of infants in the coming
months.
Dr. Chris Retajczyk , a neonatologist at California Pacific
Medical Center, said he will be paying attention to further studies
of the new score. He said he's done research into other scoring
systems to improve on the Apgar and found them often more reliable.
But they're also overly complicated, he said. The appeal of Apgar
is that it's simple and quick -- a score that shows up
automatically on a medical monitor would be even better, he said.
Retajczyk said he'll be especially interested in the PhysiScore
if it's able to accurately predict a wide variety of long-term
health outcomes.
"In general, we know how to treat these kids and maximize our
resources. The scores may make our ears perk up a bit, but it's not
going to be a major change to care," Retajczyk said. "But if we
can show a much more predictive value, like if there's a 90 percent
likelihood of (gastro-intestinal) problems, that would be really
helpful."
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SCORING METHODS
The Apgar score is given to all newborns immediately after
birth, and again five minutes later. The score is given on a scale
of 1 to 10, with higher scores correlating to better health. Five
factors are included in the score:
Activity and muscle tone: whether the baby is active and
squirming.
Pulse: the baby's heart rate.
Grimace response: how the baby reacts when stimulated.
Appearance: the baby's skin color.
Respiration: the baby's breathing and how well he or she cries.
The newly developed PhysiScore is a complex computer algorithm
that collects vital signs from infants during the first three hours
of life. The score is on a scale of 0 to 1, with higher scores
indicating a greater likelihood of serious health problems. Ten
factors are included in the equation:
Gestational age.
Birth weight.
Mean heart rate, heart rate at birth, and change in heart rate
over time.
Mean respiratory rate, rate at birth, and change in rate over
time.
Mean oxygen saturation and the total amount of time at low
oxygen levels.
c.2010 San Francisco Chronicle