Neonates with mild hypoxic-ischaemic encephalopathy receiving supportive care versus therapeutic hypothermia in California

OBJECTIVE: The use of therapeutic hypothermia (TH) for mild hypoxic-ischaemic encephalopathy (HIE) remains controversial and inconsistent. We analysed trends in TH and maternal and infant characteristics associated with short-term outcomes of infants with mild HIE. DESIGN: Retrospective cohort analysis of the California Perinatal Quality Care Collaborative database 2010-2018. E-value analysis was conducted to determine the potential impact of unmeasured confounding. SETTING: California neonatal intensive care units. PATIENTS: 1364 neonates with mild HIE. INTERVENTIONS: Supportive care versus TH. MAIN OUTCOME MEASURES: Factors associated with TH and mortality. RESULTS: The proportion of infants receiving TH increased from 46% in 2010 to 79% in 2018. TH was more likely in the setting of singleton birth (OR 2.69, 95% CI 1.21 to 5.39), no major birth defects (OR 2.18, 95% CI 1.42 to 3.30), operative vaginal delivery (OR 3.04, 95% CI 1.80 to 5.10) and 5-minute Apgar score ≤5 (OR 3.17, 95% CI 2.43 to 4.13). Mortality was associated with small for gestational age (OR 5.79, 95% CI 1.90 to 18.48), <38 weeks' gestation (OR 7.31 95% CI 2.39 to 24.93), major birth defects (OR 11.62, 95% CI 3.97 to 38.00), inhaled nitric oxide (OR 12.73, 95% CI 4.00 to 44.53) and nosocomial infection (OR 7.98, 95% CI 1.15 to 47.03). E-value analyses suggest that unmeasured confounding may have contributed to some of the observed effects. CONCLUSIONS: Variation in management of mild HIE persists, but therapeutic drift has become more prevalent over time. Further studies are needed to assess long-term outcomes alongside resource utilisation to inform evidence-based practice.