Changing clinical characteristics of infants treated for hypoxic-ischaemic encephalopathy in England, Wales and Scotland: a population-based study using the National Neonatal Research Database.

BACKGROUND

Therapeutic hypothermia is standard of care for babies with moderate/severe hypoxic-ischaemic encephalopathy and is increasingly used for mild encephalopathy.

OBJECTIVE

Describe temporal trends in the clinical condition of babies diagnosed with hypoxic-ischaemic encephalopathy who received therapeutic hypothermia.

DESIGN

Retrospective cohort study using data held in the National Neonatal Research Database.

SETTING

National Health Service neonatal units in England, Wales and Scotland.

PATIENTS: Infants born from 1 January 2010 to 31 December 2017 with a recorded diagnosis of hypoxic-ischaemic encephalopathy who received therapeutic hypothermia for at least 3 days or died in this period.

MAIN OUTCOMES: Primary outcomes: recorded clinical characteristics including umbilical cord pH; Apgar score; newborn resuscitation; seizures and treatment on day 1.

SECONDARY OUTCOMES: recorded hypoxic-ischaemic encephalopathy grade.

RESULTS

5201 babies with a diagnosis of hypoxic-ischaemic encephalopathy received therapeutic hypothermia or died; annual numbers increased over the study period. A decreasing proportion had clinical characteristics of severe hypoxia ischaemia or a diagnosis of moderate or severe hypoxic-ischaemic encephalopathy, trends were statistically significant and consistent across multiple clinical characteristics used as markers of severity.

CONCLUSIONS

Treatment with therapeutic hypothermia for hypoxic-ischaemic encephalopathy has increased in England, Scotland and Wales. An increasing proportion of treated infants have a diagnosis of mild hypoxic-ischaemic encephalopathy or have less severe clinical markers of hypoxia. This highlights the importance of determining the role of hypothermia in mild hypoxic-ischaemic encephalopathy. Receipt of therapeutic hypothermia is unlikely to be a useful marker for assessing changes in the incidence of brain injury over time.