Trends in HIE and Use of Hypothermia in California: Opportunities for Improvement

Hypoxic-ischemic encephalopathy (HIE) is a leading cause of neonatal morbidity and mortality. Therapeutic hypothermia (TH), a proven treatment of moderate-severe HIE, was first used clinically after 2006. We describe trends in HIE diagnosis and use of TH over a 10-year period in California.

We identified 62 888 infants, ≥36 weeks gestation, who were cared for in California Perinatal Quality Care Collaborative-participating NICUs between 2010 and 2019, and linked them to birth certificate data. We evaluated trends in HIE diagnosis and use of TH.

Over time, rates of HIE diagnosis increased from 0.6 to 1.7 per 1000 live births, and use of TH increased from 26.5 to 83.0 per 1000 infants. Rates of moderate HIE increased more than mild or severe, although use of TH for mild HIE increased more than for moderate. Of those with moderate-severe HIE, 25% remain untreated. Treatment varied by NICU level of care.

The rates of HIE and TH increased steadily. Some infants with moderate-severe HIE remain untreated, suggesting a need for ongoing education. Further evaluation of systems of care is needed to assure all qualifying infants are treated.