An observational, multicenter, registry-based cohort study of Turkish Neonatal Society in neonates with Hypoxic ischemic encephalopathy
Authors: Okulu Emel , Hirfanoglu Ibrahim Murat , Satar Mehmet , Erdeve Omer , Koc Esin , Ozlu Ferda , Gokce Mahmut , Armangil Didem , Tunc Gaffari , Demirel Nihal , Unal Sezin , Ozdemir Ramazan , Deveci Mehmet Fatih , Akar Melek , Demirel Melike Kefeli , Çetinkaya Merih , Buker Halime Sema Can , Karagöl Belma Saygılı , Yaprak Deniz , Akcan Abdullah Barıs , Anik Ayse , Narter Fatma , Arayici Sema , Yildirim Egemen , Akin Ilke Mungan , Sahin Ozlem , Ozdemir Ozgul Emel Bulut , Ovali Fahri , Akin Mustafa Ali , Celik Yalcin , Orman Aysen , Uslu Sinan , Ozkan Hilal , Koksal Nilgun , Tastekin Ayhan , Gunduz Mehmet , Arisoy Ayse Engin , Gurpinar Resat , Ors Rahmi , Altunhan Huseyin , Kececi Ramazan , Yildizdas Hacer Yapicioglu , Terek Demet , Ates Mehmet , Kader Sebnem , Mutlu Mehmet , Çelik Kıymet , Yucesoy Ebru , Mert Mustafa Kurthan , Gulasi Selvi , Kucuktasci Kazım , Arman Didem , Hekimoglu Berna , Gultekin Nazlı Dilay , Celik Hasan Tolga , Kahvecioglu Dilek , Akyildiz Can , Taşkın Erdal , Ciftdemir Nukhet Aladag , Uygun Saime Sundus , Kaya Tugba Barsan , Akdag Arzu , Yilmaz Aslan 
Published: December 2023

Background
Hypoxic ischemic encephalopathy (HIE) is a significant cause of mortality and short- and long-term morbidities. Therapeutic hypothermia (TH) has been shown to be the standard care for HIE of infants ≥36 weeks gestational age (GA), as it has been demonstrated to reduce the rates of mortality, and adverse neurodevelopmental outcomes. This study aims to determine the incidence of HIE in our country, to assess the TH management in infants with HIE, and present short-term outcomes of these infants.

Methods
The Turkish Hypoxic Ischemic Encephalopathy Online Registry database was established for this multicenter, prospective, observational, nationally-based cohort study to evaluate the data of infants born at ≥34 weeks GA who displayed evidence of neonatal encephalopathy (NE) between March, 2020 and April 2022.

Results
The incidence of HIE among infants born at ≥36 weeks GA (n = 965) was 2.13 per 1000 live births (517:242440), and accounting for 1.55% (965:62062) of all neonatal intensive care unit admissions. The rates of mild, moderate and severe HİE were 25.5% (n = 246), 58.9% (n = 568), and 15.6% (n = 151), respectively. Infants with severe HIE had higher rates of abnormal magnetic resonance imaging (MRI) findings, and mortality (p<0.001). No significant difference in mortality and abnormal MRI results was found according to the time of TH initiation (<3 h, 3–6 h and >6 h) (p>0.05). TH was administered to 85 (34.5%) infants with mild HIE, and of those born of 34–35 weeks of GA, 67.4% (n = 31) received TH. A total of 58 (6%) deaths were reported with a higher mortality rate in infants born at 34–35 weeks of GA (OR 3.941, 95% Cl 1.446–10.7422, p = 0.007).

Conclusion
The incidence of HIE remained similar over time with a reduction in mortality rate. The timing of TH initiation, whether <3 or 3–6 h, did not result in lower occurrences of brain lesions on MRI or mortality. An increasing number of infants with mild HIE and late preterm infants with HIE are receiving TH; however, the indications for TH require further clarification. Longer follow-up studies are necessary for this vulnerable population.