Determinants of outcomes after head cooling for neonatal encephalopathy.
OBJECTIVE
The goal of this study was to evaluate the role of factors that may determine the efficacy of treatment with delayed head cooling and mild systemic hypothermia for neonatal encephalopathy.


METHODS
A total of 218 term infants with moderate to severe neonatal encephalopathy plus abnormal amplitude-integrated electroencephalographic recordings, assigned randomly to head cooling for 72 hours, starting within 6 hours after birth (with the rectal temperature maintained at 34.5 +/- 0.5 degrees C), or conventional care, were studied. Death or severe disability at 18 months of age was assessed in a multicenter, randomized, controlled study (the CoolCap trial).


RESULTS
Treatment, lower encephalopathy grade, lower birth weight, greater amplitude-integrated electroencephalographic amplitude, absence of seizures, and higher Apgar score, but not gender or gestational age, were associated significantly with better outcomes. In a multivariate analysis, each of the individually predictive factors except for Apgar score remained predictive. There was a significant interaction between treatment and birth weight, categorized as > or =25th or <25th percentile for term, such that larger infants showed a lower frequency of favorable outcomes in the control group but greater improvement with cooling. For larger infants, the number needed to treat was 3.8. Pyrexia (> or =38 degrees C) in control infants was associated with adverse outcomes. Although there was a small correlation with birth weight, the adverse effect of greater birth weight in control infants remained significant after adjustment for pyrexia and severity of encephalopathy.


CONCLUSIONS
Outcomes after hypothermic treatment were strongly influenced by the severity of neonatal encephalopathy. The protective effect of hypothermia was greater in larger infants.
Wyatt
John S
JS
Department of Paediatrics and Child Health, University College London, London, United Kingdom.
Gluckman
Peter D
PD
Liu
Ping Y
PY
Azzopardi
Denis
D
Ballard
Roberta
R
Edwards
A David
AD
Ferriero
Donna M
DM
Polin
Richard A
RA
Robertson
Charlene M
CM
Thoresen
Marianne
M
Whitelaw
Andrew
A
Gunn
Alistair J
AJ
D004569:Electroencephalography; D005260:Female; D006257:Head / Q000502:physiology; D006801:Humans; D007036:Hypothermia, Induced / Q000379:methods*; D020925:Hypoxia-Ischemia, Brain / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D007231:Infant, Newborn; D008297:Male