Defining hypoxic ischemic encephalopathy in newborn infants: benchmarking in a South African population

Objectives: There are few population-based studies of hypoxic ischemic encephalopathy (HIE) in sub-Saharan Africa, and the published criteria that are used to define and grade HIE are too variable for meaningful comparisons between studies and populations. Our objectives were (1) to investigate how the incidence of HIE in our region varies with different criteria for intrapartum hypoxia and (2) to determine how encephalopathy severity varies with different grading systems. Method: We reviewed the records of infants with a diagnosis of HIE born between September 2008 and March 2009 in public facilities in the Southern Cape Peninsula, South Africa. The incidence of HIE was calculated according to four definitions of intrapartum hypoxia and graded according to three methods. Results: Depending on which defining criteria were applied, the incidence of HIE varied from 2.3 to 4.3 per 1000 live births, of mild HIE ranged from 0.4 to 1.3 per 1000 live births, and of moderate-severe HIE ranged from 1.5 to 3.7 per 1000 live births. Ninety-seven of the 110 (88 %) infants reviewed had at least one intrapartum-related abnormality. Only 62 (56 %) infants had a blood gas performed in the first hour of life. Conclusion: The incidence and grade of HIE can vary more than 2-fold in the same population, depending on which defining criteria are used. Consensus definitions are needed for benchmarking.