Early Determination of Prognosis in Neonatal Moderate or Severe Hypoxic-Ischemic Encephalopathy

Abstract

Background and objectives: Early determination of prognosis is important in neonates with hypoxic-ischemic encephalopathy (HIE). Our objective was to test scoring systems developed earlier (original scoring system) and develop new prognostic models.

Methods: Secondary analysis of data from the multicenter randomized controlled trial of longer, deeper, or usual care cooling in neonatal HIE (NCT01192776) that enrolled 364 neonates diagnosed with moderate or severe HIE. The primary outcome was death or moderate or severe disability at 18 to 22 months, and secondary outcome was death during initial hospitalization. Testing of early neurologic clinical examination (<6 hours of age) and the original scoring system for prognostic ability was done, followed by development of new scoring systems and classification and regression tree (CART) models by using early clinical variables (<6 hours of age).

Results: For death or disability, the original scoring system correctly classified 75% (95% confidence interval: 69%-81%), whereas the new scoring system correctly classified 78% (73%-82%), and the CART model correctly classified 76% (72%-81%). Early neurologic clinical examination also had a correct classification rate of 76% (71%-80%). Depth and duration of cooling did not affect prediction. Only a few components of the early neurologic examination were associated with poor outcome. For death, the original scoring system correctly classified 72% (66%-77%), the new scoring system 68% (63%-72%), the new CART model 87% (83%-90%), and early neurologic evaluation 81% (77%-85%).

Conclusions: The 3 models (scoring system, CART, and early neurologic evaluation) were comparable in predicting death or disability. For in-hospital death, CART models were superior to scoring systems and early neurologic examination.

FIGURE 1

Interpretation of new models of death or disability and death before hospital discharge. The green range indicates all infants survived without the adverse outcome. Yellow indicates that fewer infants had a bad outcome. Red is the score range in which risk of adverse outcome was higher (>50% death or disability; 100% death).

FIGURE 2

CART model for death or disability at 18- to 22-month follow-up. In each node (rectangle), the category 0 or 1 refers to the absence or presence of death or disability, respectively, and the percentages and n values refer to the infants in each of the categories.

FIGURE 3

CART model for death during initial hospitalization. In each node (rectangle), the category 0 or 1 refers to the absence or presence of death, respectively, and the percentages and n values refer to the infants in each of the categories.

FIGURE 4

Score ranges for original models (from 2006). Green indicates all infants survived without the adverse outcome (death or disability in left panel; death in right panel). Yellow indicates some infants had a bad outcome. Red reveals the score range in which all infants developed the adverse outcome.