***TASK***
the task is to simplify the input abstract of a biomedical literature

***INPUT***
the input is the abstract of a biomedical literature

***OUTPUT***
the output is the simplified abstract for the input abstract of a biomedical literature

***DOCUMENTATION***

***EXAMPLES***

Input: Four trials, enrolling a total of 614 infants, compared low (restrictive) to high (liberal) haemoglobin thresholds. Restrictive thresholds tended to be similar, but one trial used liberal thresholds much higher than the other three. There were no statistically significant differences in the combined outcomes of death or serious morbidity at first hospital discharge (typical risk ratio (RR) 1.19; 95% confidence interval (CI) 0.95 to 1.49) or in component outcomes. Only the largest trial reported follow-up at 18 to 21 months corrected gestational age; in this study there was no statistically significant difference in a composite of death or adverse neurodevelopmental outcome (RR 1.06; 95% CI 0.95 to 1.19). One additional trial comparing transfusion for clinical signs of anaemia versus transfusion at a set level of haemoglobin or haematocrit, reported no deaths and did not address disability. The use of restrictive as compared to liberal haemoglobin thresholds in infants of very low birth weight results in modest reductions in exposure to transfusion and in haemoglobin levels. Restrictive practice does not appear to have a significant impact on death or major morbidities at first hospital discharge or at follow-up. However, given the uncertainties of these conclusions, it would be prudent to avoid haemoglobin levels below the lower limits tested here. Further trials are required to clarify the impact of transfusion practice on long term outcome.
Output:

This review of five studies compares the effects of blood transfusion at low levels of haemoglobin to transfusion at high levels. Within the levels tested, there were no differences seen in survival, in the serious complications of prematurity, or in longer term development as measured at 18 to 21 months past the baby's due date. Allowing the baby to become a little more anaemic did not affect the baby's weight gain or breathing patterns. These conclusions are not firm, because too few babies have been studied. Our overall recommendation is not to exceed the higher levels of haemoglobin used in these trials, and thus diminish the risks of over-transfusion, but not to allow the level of haemoglobin to fall below the lower limits tested in these studies until further studies are completed.