Supplementary Material for: Auditory impairment in infants with neonatal hypoxic-ischaemic encephalopathy: a systematic review and meta-analysis

Rationale and objectives
Hypoxic-ischaemic encephalopathy (HIE) due to perinatal asphyxia (PA) remains a significant cause of neonatal morbidity and mortality. Despite therapeutic hypothermia (TH), a considerable proportion of survivors experience a wide range of deficits, including auditory impairment (AI), which needs deeper knowledge.
This review aims to describe AI outcomes in infants with HIE.
Methods
A systematic literature review was performed using standard methods outlined by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol. A qualitative synthesis of all the included studies and a meta-analysis with seven eligible studies were conducted.
Results
In the sixteen studies comprised, a mean incidence of 4.54% of AI occurred among participants meeting the inclusion criteria. In the meta-analysis, in subgroup A (healthy newborns vs. newborns with HIE), an OR=10.74 with a 95% CI 2.02-57.16 and a p-value 0.010 was observed, indicating tenfold higher odds of AI in HIE newborns; subgroup B (newborns with HIE who received standard care vs. those who underwent TH) exhibited an OR= 0.77 with a 95% CI 0.35-1.68 and a p-value 0.510, demonstrating that newborns who received TH had a 0.77 fold lower odds of developing AI.
Conclusion
This review highlights HIE as a risk factor for AI and the possibility of TH being a protective factor. However, the variations in participant characteristics, HIE criteria, and methods of hearing assessment contribute to significant variability between studies, identifying the need for a standard evaluation of auditory outcomes in this setting, and extended over long-term.