Table 2

Haemoglobin transfusion thresholds and primary outcome for ETTNO and TOP trials

StudyETTNO trial24 TOP trial25
Transfusion threshold groupHigherLowerHigherLower
Severity stratumCriticalNon-criticalCriticalNon-criticalRespiratory supportNo respiratory supportRespiratory supportNo respiratory support
Haemoglobin threshold,* g/dL
 Week 113.711.711.39.313.
 Weeks 2–3 (ETTNO) or 2 (TOP)12.310.310.08.012.511.010.08.5
 Week >3 (ETTNO) or ≥3 (TOP)
Primary outcomeNeurodevelopmental impairment† at 2 years’ corrected age or death before assessmentNeurodevelopmental impairment‡ at 2 years’ corrected age or death before assessment
  • *Thresholds varied with postnatal age and/or degree of illness24 or level of respiratory support25; haematocrit thresholds24 were converted to haemoglobin levels by dividing by 3.

  • †Neurodevelopmental impairment defined as any of the following: (1) cognitive deficit, defined as Bayley-II Mental Developmental Index (MDI) score <85, Bayley-II cognitive raw score below the lower margin of the MDI, inability to be tested because of severe impairment, another cognitive test score of >1 SD below the mean or assessment by the child’s paediatrician of cognitive deficit; (2) cerebral palsy, defined according to the Surveillance of Cerebral Palsy in Europe network; or (3) severe visual or hearing impairment, defined as best-corrected visual acuity of <6/60 and/or need for hearing aid or cochlear implant.

  • ‡Neurodevelopmental impairment defined as any of the following: (1) cognitive delay, defined as Bayley-III composite cognitive score <85; (2) moderate or severe cerebral palsy, defined as Level II or higher on the Gross Motor Function Classification System26; (3) severe vision loss, defined as corrected visual acuity in the better eye of <20/200; or (4) severe hearing impairment, defined as bilateral hearing loss requiring hearing aids or cochlear implants.