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Hypothermia's Benefits for Neonatal Encephalopathy Confirmed


 

FROM THE NEW ENGLAND JOURNAL OF MEDICINE

Whole-body hypothermia reduced the rate of death in patients with moderate to severe neonatal encephalopathy without raising the rate of neurodevelopmental deficits in a study that followed 190 children to age 6-7 years, according to a report in the May 31 issue of the New England Journal of Medicine.

Until now, data "have not been available to assess whether the benefits of hypothermia for neonatal hypoxic-ischemic encephalopathy persist after 2 years of age," said Dr. Seetha Shankaran, director of the division of neonatal-perinatal medicine at Wayne State University, Detroit, and her associates.

"These results are reassuring since hypothermia is being used extensively around the world and currently is recommended by health care policymakers," they noted.

The investigators used data from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Neonatal Research Network to assess the long-term rates of death, cognitive impairment, and other neurodevelopmental outcomes in 190 children born in 2000-2003. All the study subjects were diagnosed as having moderate to severe encephalopathy within 6 hours of birth, after an acute perinatal event causing severe acidosis or necessitating resuscitation.

The neonates had been randomly assigned either to undergo whole-body hypothermia at 33.5° C for 72 hours (97 patients) or to usual care (93 patients).

The primary outcome measure – a combination of death or an IQ score below 70 at 6-7 years of age – occurred in 47% of the hypothermia group and 62% of the control group. There were 27 deaths in the hypothermia group and 41 in the control group. In the hypothermia group, 27% of the children attained an IQ score below 70, compared with 33% of the control group. The mean IQ score was 82 with hypothermia and 75 in the control group.

These rates showed a benefit with hypothermia, but the difference between the two groups in the composite primary outcome just failed to reach statistical significance.

When the combined outcome was broken down into its individual parts, however, hypothermia was found to significantly improve mortality, "with no appreciable increase in the risk of neurodevelopmental deficits among survivors," said Dr. Shankaran, who is also director of regional neonatal programs at Children’s Hospital of Michigan, Detroit, and her colleagues.

The secondary composite outcomes of death or severe disability and of death or cerebral palsy were significantly lower in children who had undergone hypothermia. In particular, the rate of cerebral palsy was 17% with hypothermia and 29% in the control group; the rate of blindness was 1% with hypothermia, compared with 4% in the control group, the investigators said (N. Engl. J. Med. 2012;366:2085-92).

"We did not find a decrease in the risk of abnormalities in motor function among nondisabled children in the hypothermia group as compared with those in the control group," the researchers said.

There also were no significant differences between the two groups in measures of attention, executive function, and visuospatial ability.

Children with cerebral palsy are known to have "markedly poor" health, but previous studies have found that "the psychosocial health of children and the emotional impact of the child’s health on the parents tend to be similar regardless of the level of disability," they said.

In this study, parents’ assessments of the child’s health or self-esteem did not differ significantly between children who received hypothermia and the control group, and ratings of the emotional impact of the child’s well-being on the parents also were not significantly different, Dr. Shankaran and her associates said.

With any therapy that reduces mortality in infants at high risk of disability, there is a concern that the number who survive with disability will increase. However, "as reported here, there was no evidence of increased rates of an IQ score below 70, severe disability, or cerebral palsy at 6 to 7 years of age among surviving children treated with hypothermia," the investigators said.

This study was supported by the National Institutes of Health and the Eunice Kennedy Shriver NICHD Neonatal Research Network. Some of Dr. Shankaran’s associates reported ties to Olympic Medical/Natus Corp., MedImmune, Pfeiffer Research Foundation, and the Robertson Foundation, as well as being recipients of various institutional and governmental grants.

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