Neurodevelopmental outcome of extremely low birth weight infants randomly assigned to restrictive or liberal hemoglobin thresholds for blood transfusion.
The report on the short-term outcome of patients who participated in the PINT (Pre-term In Need of Transfusion) study was published a few years ago (Pediatrics 2006;149:301-7). In this randomized multicenter clinical trial, 451 extremely low birth weight (ELBW) infants were allocated either to a restrictive or a liberal transfusion strategy. The average difference in hemoglobin concentration was 11 g/L for 12 weeks; thereafter, no difference was detected. Surprisingly, there was no difference in the number of transfusions given in the two groups. Evaluation of short-term outcome showed no difference.
Recently, Whyte and colleagues published data collected 18 to 21 months after the PINT study was completed (Pediatrics 2009;123:207-13). Again, no difference was found for all outcomes preplanned in the original trial (death or a composite outcome including retinopathy, chronic lung disease and white matter injury). However, a “posthoc analysis with cognitive delay redefined (Mental Development Index score < 87) showed a significant difference favoring the liberal threshold group." Actually, the difference in cognitive function is so small (85.2 versus 88.7) that one can wonder if it is clinically significant. Moreover, it is disturbing to find something positive when the difference in hemoglobin concentration was so small (11 g/L). Posthoc analyses must be considered as hypothesis-generating. Therefore, these results must be interpreted with great caution. I believe that it would be unethical to conclude that it is better to give more transfusions to ELBW infants since there was no difference at all in the number of transfusions received by patients in the restrictive and the liberal groups of the PINT study. More investigations are mandatory before a liberal transfusion strategy is applied to ELBW infants. – Jacques Lacroix