Benefits of Hypothermia for Infants Extend Through Early Childhood

RESEARCH TRIANGLE PARK, N.C. — A treatment to reduce the body temperatures of infants who experience oxygen deficiency at birth has benefits into early childhood, according to a follow-up study by a National Institutes of Health research network.

Children who received the hypothermia treatment as infants were more likely to have survived when evaluated again at ages 6 and 7 than were children who received routine care, and no more likely than the routine care group to experience a physical or cognitive impairment, the study found.

The study was conducted by the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network (https://neonatal.rti.org).

As data coordinating center for the network, RTI International coordinated the conduct of this study, managed all data and led the statistical analysis of the data used in drawing conclusions.

"The findings show that using hypothermia treatment after birth not only increases the child's chances of survival, but does so without increasing the risk of long-term disability," said Scott McDonald, RTI statistician on the project and paper co-author.

Oxygen deprivation during the birth process is called hypoxic-ischemic encephalopathy, or HIE. In severe cases, death rates can reach 50 percent. Survivors often sustain brain damage, which can result in cerebral palsy, cognitive impairment or hearing and vision loss. Even if they do not experience detectable brain damage, children who experience HIE at birth are at higher risk for learning disabilities, language delays and memory deficits.

The current study was in follow up to an earlier study, conducted when the children were newborns and had received the body cooling treatment shortly after birth in a randomized clinical trial. That earlier study found that infants who received the cooling treatment were less likely to die or to develop moderate or severe disability than were the infants who received routine care. The current study assessed children's movement and cognitive abilities, hearing, and vision when they were 6 or 7 years old.

"This follow-up study showed that the children who received cooling treatment were no more likely to experience cognitive or physical impairments as they grew up when compared to those who did not receive treatment," said Abhik Das, Ph.D., RTI's principal investigator on the project and a paper co-author.

The findings appear in the New England Journal of Medicine.

The 208 children in the study were diagnosed with HIE within six hours of birth and treated in newborn intensive care units in the network. They were either given the usual intensive care or treated with the whole body cooling technique.

To conduct the current study, the researchers analyzed data from follow-up visits conducted when these infants had turned 6 or 7. The researchers compared rates of death and disability among those who got the cooling therapy and those who had received the usual intensive care. Mortality rates reflected the number of children who died between birth and age 7: 28 percent in the hypothermia group, compared with 44 percent in the usual care group.

The researchers calculated the number of deaths and cases of severe disability as a single, combined outcome. In the cooling group, the combined rate was 41 percent, compared with 60 percent in the usual care group. Severe disability involved motor function, cognitive ability and vision. Rates of cerebral palsy, blindness and epilepsy were similar between the two groups.

The researchers also evaluated combined rates of death and IQ below 70. For the cooling group, this figure was 47 percent, compared with 62 percent in the usual care group. Though analysis showed that this was not a statistically significant difference, there was a statistically significant reduction in death, as well as the combined rate of death or cerebral palsy in the cooling group compared to the usual care group.

RTI's data coordinating center provides data management and biostatistical support and consultation in the areas of design, execution and analysis for studies conducted by the Neonatal Research Network. RTI also assists in the development of study materials, including protocols, study manuals and forms.

For more information about the study, see the journal article on the New England Journal of Medicine website.