Table 2.
Primary Composite Outcome and Components of the Primary Composite Outcome at 2 Years.*
| Outcome | Higher Hemoglobin Threshold (N = 845) | Lower Hemoglobin Threshold (N = 847) | Adjusted Relative Risk (95% CI) | P Value |
|---|---|---|---|---|
| no. of infants/total no. (%) | ||||
| Primary outcome: death or neurodevelopmental impairment | 423/845 (50.1) | 422/847 (49.8) | 1.00 (0.92–1.10) | 0.93 |
| Components of primary outcome | ||||
| Death† | 146/903 (16.2) | 135/901 (15.0) | 1.07 (0.87–1.32) | |
| Neurodevelopmental impairment | 277/699 (39.6) | 287/712 (40.3) | 1.00 (0.88–1.13) | |
| Cognitive delay‡ | 269/695 (38.7) | 270/712 (37.9) | 1.04 (0.91–1.18) | |
| Moderate or severe cerebral palsy§ | 48/711 (6.8) | 55/720 (7.6) | 0.87 (0.60–1.26) | |
| Severe vision impairment | 5/713 (0.7) | 6/720 (0.8) | 0.83 (0.25–2.76)¶ | |
| Severe hearing impairment | 14/710 (2.0) | 25/715 (3.5) | 0.56 (0.29–1.07)¶ | |
The relative risk was adjusted for birth-weight and center stratum. The P value is reported only for the composite primary outcome. For the secondary outcomes, 95% confidence intervals (CIs) were not adjusted for multiplicity and should not be used to infer definitive treatment effects.
Infants with incomplete follow-up but with known vital status were included in these numbers. Five infants in each group had unknown vital status at the start of the 2-year follow-up window.
Cognitive delay was defined as a composite cognitive score of less than 85 (1 SD below the mean of 100) on the Bayley Scales of Infant and Toddler Development (BSID-III), third edition; scores range from 55 to 145, with higher scores indicating better performance.10
Moderate or severe cerebral palsy was defined as a Gross Motor Function Classification System level II or higher (levels range from I [mild impairment] to V [most severe impairment]). Level II denotes moderate cerebral palsy with a limited ability to walk. Levels III to V indicate increasing severity of gross motor impairment.
Trial centers with low incidences of blindness or hearing impairment were pooled with their nearest geographic center before estimation of adjusted relative risks.