Primary and main secondary outcomes in ETTNO and TOP trials
| Transfusion threshold group | ETTNO trial24 | TOP trial25 | ||
| Higher | Lower | Higher | Lower | |
| No of subjects randomised | 492 | 521 | 911 | 913 |
| Mean gestational age, weeks | 26 | 26 | 26 | 26 |
| Approximate haemoglobin separation between higher and lower groups* | 1.0 g/dL | 2.0 g/dL | ||
| Infants with delayed cord clamping or cord milking, % | 63 | 61 | 27 | 24 |
| No of subjects with primary outcome, neurodevelopmental impairment or death | 450 | 478 | 845 | 847 |
| Overall follow-up rate per study including both Higher and Lower groups, % | 91.6 | 92.8 | ||
| Primary outcome, % – OR24 or adjusted relative risk25 (95% CI) | 44.4 | 42.9 | 50.1 | 49.8 |
| 1.05 (0.80 to 1.39) | 1.00 (0.92 to 1.10) | |||
| Death, % – OR24 or adjusted relative risk25 (95% CI) | 8.3 | 9.0 | 16.2 | 15.0 |
| 0.91 (0.58 to 1.45) | 1.07 (0.87 to 1.32) | |||
| Neurodevelomental impairment, % – OR24 or adjusted relative risk25 (95% CI) | 37.6 | 35.9 | 39.6 | 40.3 |
| 1.12 (0.83 to 1.51) | 1.00 (0.88 to 1.13) | |||
| Mean no of transfusions | 2.6 | 1.7† | 6.2 | 4.4‡ |
| Infants never transfused, % | 21 | 40‡ | 3 | 12‡ |
| Necrotising enterocolitis§, % | 5.3 | 6.2 | 10.0 | 10.5 |
| Patent ductus arteriosus§, % | 41.5 | 37.8 | 44.5 | 47.8 |
| Retinopathy of prematurity§, grade ≥3, % | 15.9 | 13.0 | 19.7 | 17.2 |
| Severe intraventricular haemorrhage or periventricular leucomalacia§¶ | No significant difference | No significant difference | ||
| Bronchopulmonary dysplasia** | 28.4 | 26.0 | 59.0 | 56.3 |
*Estimated from figure 2 for the ETTNO trial and from figure 2A for the TOP trial.
†Unable to compute p value for means, although the medians reported in eTable 224 were 2 and 1, and the IQRs overlapped.
‡Significantly different (p<0.05), higher vs lower transfusion threshold group.
§The differences between higher and lower groups were not significant for either trial.
¶The values are not comparable between studies because severe intraventricular haemorrhage and periventricular leucomalacia were combined in TOP but not in ETTNO.
**Bronchopulmonary dysplasia defined as oxygen use at 36 weeks’ postmenstrual age.