EBNEO COMMENTARY: Safety and Efficacy of Erythropoietin in neonates with Hypoxic-Ischaemic Encephalopathy.

January 20, 2023


Wu YW, Comstock BA, Gonzalez FF, Mayock DE, Goodman AM, Maitre NL et al. Trial of Erythropoietin for Hypoxic–Ischemic Encephalopathy in Newborns. N Engl J Med 2022; 387:148-159. PMID: 35830641


Dr Lorraine Marie Chung, MD
Mackay Base Hospital

Dr Gopakumar Hariharan, MD FRACP
Mackay Base Hospital




In neonates, more than 36 weeks gestation, with hypoxic-ischaemic encephalopathy (Population), is high dose of erythropoietin (1000U/kg) (Intervention) safe and efficacious (Outcome) in conjunction with therapeutic hypoxia compared to placebo (Comparison) over a period of 22 to 36 months (Time).


  • Design: Multicentre Randomised controlled trial
  • Allocation: 50:50 randomised allocation ratio
    • Randomisation was stratified according to trial site and severity of encephalopathy
  • Blinding: Double blinded
  • Follow-up period: 22-36 months of age
  • Setting: 23 hospitals in the United States
  • Patients: 501 infants
    • Inclusion Criteria: Neonates ≥ 36 weeks gestational age under 23 hours of age at time of consent meeting all the criteria below
  1. Perinatal depression based on at least one of the following:
    1. Apgar score <5 at 10 minutes OR
    2. cardiorespiratory resuscitation beyond 10 minutes of age OR
    3. pH <7.00 in cord blood arterial or venous blood gas less than 60 minutes of age OR
    4. base deficit ≥15 in cord, arterial or venous blood gas less than 60 minutes of age
  2. Moderate to severe encephalopathy based on the presence of at least three of six Sarnat criteria present at 1-6 hours of age
    1. Reduced consciousness
    2. Decreased spontaneous activity
    3. Hypotonia
    4. Decreased suck reflex
    5. Decreased Moro reflex
    6. Respiratory abnormality
  3. Passive or active hypothermia started within 6 hours after birth and continued for 72 hours
    • Exclusion criteria
      • Birthweight less than 1800g
      • Head circumference of less than 30cm
      • Genetic or congenital condition affecting neurodevelopment
      • Hematocrit more than 65%
      • Parents considering redirection to palliative care
      • Encephalopathy attributed to a postnatal event
      • Surviving twin undergoing therapeutic hypothermia
      • Anticipation that the child would be unavailable for evaluation at 2 years of age
    • Intervention: Erythropoietin (Epogen, Amgen; 4000U per millilitre) at a dose of 1000 Units per kilogram or an equal volume of saline as placebo IV before 26 hours of age and at 2, 3, 4, and 7 days of age.
    • Outcomes:
      • Standardised neurological and developmental assessments at 22-36 months for primary and secondary outcomes.
      • Primary outcome: death or neurodevelopmental impairment of any severity at 22-36 months of age, defined as the presence of any of the following:
  1. Cerebral Palsy
  2. Bayley III Cognitive Score <90
  3. GMFCS level ≥1
    • Secondary outcomes:
      • Four-level ordinal outcome:
        • Death
        • Cerebral Palsy
        • Severity of motor impairment
        • Bayley III cognitive and language scores
        • Moderate or severe neurodevelopment impairment
          • GMFCS level 1 and cerebral palsy
          • GMFCS level ≥2
          • Quadriplegic cerebral palsy
          • BSID-III score of <85
        • Mild or no neurodevelopmental impairment
        • Parental report of seizures, vision impairment and hearing loss
        • Behavioural abnormalities based on the Child Behaviour Checklist (CBCL) externalising score of 65 or more
      • Neonatal brain MRI using harmonized neuroimaging protocol at 4-6 days after birth when possible
  • Analysis and Sample Size:
    • The incidence of the primary outcome (death or neurodevelopmental impairment) was estimated to be 49% among neonates who received a placebo. Cumulative incidence was estimated to be 31-35% among those who received erythropoietin (relative risk 0.65-0.71). The sample size of 500 infants was computed assuming a 90% follow up rate for the trial to have greater than 90% power to detect a relative risk difference of 33%.
    • Analysis was based on a modified intention to treat approach.
    • Primary outcomes were evaluated with likelihood-ratio tests based on logistic regression. Proportional-odds regression models were used to compare ordered categorical secondary outcomes. All other secondary outcomes were assessed using adjusted linear (continuous) or logistic (binary) regression models.
    • Odds ratios and 95% confidence intervals were estimated for each of the outcomes.
    • Regarding the primary outcomes and serious adverse event outcomes, the statistical significance threshold was set at a p-value less than 0.05.
  • Patient follow-up: % included in analysis
    • Of 1300 infants assessed for eligibility, 501 were recruited. One infant of the 501 did not receive a trial intervention owing to not meeting the inclusion criteria.
    • 257 (51.4%) infants were assigned to and received erythropoietin while 243 (48.6%) were assigned to and received placebo.
    • Evaluation of primary outcomes at 22-36 months of age included 240 (93.4%) infants in the erythropoietin group and 222 (91.4%) in the placebo group

Main Results:

Table 1: Primary Outcomes

Outcome Measure


Erythropoietin Group (n=257) Placebo Group (n=243) Relative Risk (95% Confidence Interval )
Death or Neurodevelopmental Impairment 126 (52.5%) 110 (49.5%) 1.03 (0.86-1.24)
Death 37 (14.4%) 28 (11.5%) 1.24 (0.78-1.23)
Any neurodevelopmental Impairment 89 (43.8%) 82 (42.3%) 0.97 (0.77-1.99)
BSID III Cognitive Score <90 77 (38.5%) 78 (40.4%) 0.90 (0.70-1.16)
Cerebral Palsy 31 (15.4%) 24 (12.4%) 1.10 (0.70-1.73)
GMFCS level ≥1 19 (9.4%) 19 (9.8%) 0.95 (0.52-1.75) 

Secondary Outcomes

The results for the ordinal secondary outcomes (death, moderate or severe neuro- developmental impairment, mild impairment, or no impairment) showed minimal difference between the erythropoietin and placebo group.

Behavioural abnormalities, as reported by the Childhood Behaviour Checklist of ≥65, was more than four times in the erythropoietin group (7.2% of infants) compared to the placebo group (1.5%). 

Neonatal Brain MRI Findings

Pattern of Brain Injury Erythropoietin Group (n=242) Placebo Group (n=231) Group Comparison (95% Confidence Interval)
Central grey or posterior limb of internal capsule 96 (39.7%) 78 (33.8%) 1.17 (0.92-1.48)
Peripheral Watershed 57 (23.6%) 71 (26.4%) 0.88 (0.64-1.22)
Other 23 (9.5%) 32 (13.9%) 0.70 (0.42-1.16)


The authors concluded that erythropoietin treatment for neonates with hypoxic-ischaemic encephalopathy undergoing therapeutic hypothermia did not lower risk of death or neurodevelopmental impairment at 22-36 months.

There was an increased mean number of serious adverse events in the erythropoietin group (86%) compared to the placebo (67%). Additionally, the erythropoietin population was found to be 21% more likely to have one or more serious adverse events.


Therapeutic hypothermia remains the only proven treatment to improve mortality and morbidity in neonates with hypoxic ischaemic encephalopathy (HIE).1 Preclinical models have demonstrated erythropoietin as a potential adjuvant therapy in neonatal HIE due to its neuroprotective and neuro-regenerative effects.1 The anti-inflammatory and anti-oxidant effects of erythropoietin promotes neurogenesis through remodelling of brain tissue after HIE.2 The neuroprotective effects of erythropoietin results from its binding to erythropoietin receptors on mature neurons and neuronal progenitors causing induction of antiapoptotic genes.2

The data from small clinical trials suggests that erythropoietin monotherapy for neonates with moderate to severe HIE reduces the risk of cerebral palsy and moderate to severe cognitive impairment.2, 3 Furthermore, erythropoietin with or without hypothermia demonstrated reduced risk of brain injury on MRI in two randomised control trials.2 Previous randomised control trials investigating erythropoietin in combination with therapeutic hypothermia has shown promising results of neuroprotective benefit although were limited by small sample size.2 A small randomised controlled trial by Saad et al., which included 33 neonates with HIE demonstrated lower occurrence of clinically detectable seizures in the first week of life.4

Conversely, preclinical data in studies by Fan et al. and Fang et al. did not demonstrate positive effects of erythropoietin in HIE.1 Furthermore, the study conducted by Wassink et al.5 in near-term fetal sheep concluded that high-dose erythropoietin may not be an effective adjuvant therapy in HIE.5

This phase III study by Wu et al. concluded no improvement in neurodevelopmental outcome in neonates with HIE following combined erythropoietin intervention and therapeutic hypothermia compared to placebo. Behavioural abnormalities were found to be four times greater in the erythropoietin group compared to placebo, however this will need further investigation by a follow up study beyond 36 months of age. The study concluded a higher risk of serious adverse events in the erythropoietin group compared to the placebo group.

The conclusions regarding adverse effects from the study by Wu et al., is in contrast with prior systematic reviews conducted by Razak and Hussain2 (2018) and Ivain et al.6 (2021) which demonstrated erythropoietin monotherapy not to be associated with significant adverse outcomes or complications. Furthermore, Oorschot et al.1 and Garg et al.7 showed no adverse effects in studies of combined erythropoietin and therapeutic hypothermia in treatment of babies with HIE.

A wide range of adverse effects were monitored during different clinical trials.1, 2, 6, 7  Wu et al. combined various adverse events which included “death, systemic hypertension, polycythaemia, disseminated intravascular coagulation, major venous or arterial thrombosis, pulmonary hypertension, intracranial haemorrhage, cardiopulmonary arrest or other unexpected life-threatening event” into the composite outcome of “serious adverse events”. The results of this single randomised control trial showing contrasting results compared to prior meta-analysis studies in terms of adverse events could be due to variation in parameters and classifications used in different trials.

The results of the ongoing trial “Erythropoietin for Hypoxic Ischaemic Encephalopathy in Newborns” (PAEAN) is likely to provide more information on erythropoietin’s adverse effects and neuroprotective effects.8 Further larger-scale studies on the use of erythropoietin without hypothermia would be important, particularly in resource-limited countries where the option of therapeutic hypothermia is limited and most injury related to HIE is sub-acute.9


  1. Oorschot DE, Sizemore RJ, Amer AR. Treatment of Neonatal Hypoxic-Ischemic Encephalopathy with Erythropoietin Alone, and Erythropoietin Combined with Hypothermia: History, Current Status, and Future Research. Int J Mol Sci. 2020;21(4).
  2. Razak A, Hussain A. Erythropoietin in perinatal hypoxic-ischemic encephalopathy: a systematic review and meta-analysis. J Perinat Med. 2019;47(4):478-89.
  3. Perrone S, Lembo C, Gironi F, Petrolini C, Catalucci T, Corbo G, et al. Erythropoietin as a Neuroprotective Drug for Newborn Infants: Ten Years after the First Use. Antioxidants (Basel). 2022;11(4).
  4. Saad K, Badr-El Din M, Abougabal ASH, Abdel-Salam H. Effect of erythropoietin as adjunctive therapy with whole-body cooling for treatment of hypoxic-ischemic encephalopathy in newborns. Alexandria Journal of Pediatrics. 2017;30(2).
  5. Wassink G, Davidson JO, Crisostomo A, Zhou KQ, Galinsky R, Dhillon SK, et al. Recombinant erythropoietin does not augment hypothermic white matter protection after global cerebral ischaemia in near-term fetal sheep. Brain Commun. 2021;3(3):fcab172.
  6. Ivain P, Montaldo P, Khan A, Elagovan R, Burgod C, Morales MM, et al. Erythropoietin monotherapy for neuroprotection after neonatal encephalopathy in low-to-middle income countries: a systematic review and meta-analysis. J Perinatol. 2021;41(9):2134-40.
  7. Garg B, Sharma D, Bansal A. Systematic review seeking erythropoietin role for neuroprotection in neonates with hypoxic ischemic encephalopathy: presently where do we stand. J Matern Fetal Neonatal Med. 2018;31(23):3214-24.
  8. Liley H, Hunt R, Jacobs S, Badawi N, Novak I, Askie L, et al. Preventing adverse outcomes of neonatal hypoxic ischaemic encephalopathy with erythropoietin: A Phase III randomised placebo controlled multi- centre clinical trial. ClinicalTrials.gov Identifier: NCT03079167. Updated September 22, 2022. Accessed November 29, 2022. https://www.clinicaltrials.gov/ct2/show/NCT03079167
  9. Thayyil S, Pant S, Montaldo P, Shukla D, Oliveira V, Ivain P, et al. Hypothermia for moderate or severe neonatal encephalopathy in low-income and middle-income countries (HELIX): a randomised controlled trial in India, Sri Lanka, and Bangladesh. Lancet Glob Health. 2021;9(9):e1273-e85.

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