"It would be premature to base changes in medical practice on the data this study provides," he said, noting it can be difficult to draw definitive conclusions based on research that looks back on patient experience without controlling for all the various factors that might color the findings.
For example, "the sicker patients received more blood than the less sick patients, and were therefore more likely to receive at least one older unit," he pointed out. "[So] it is not possible to discern whether the worse clinical condition caused more old blood to be transfused, or if the patients were sicker because they received more old blood."
Noting that research is under way to try to answer such questions, Benjamin emphasized that "the judicious use of blood transfusion is lifesaving and allows the performance of medical and surgical procedures that would not otherwise be possible due to blood loss. Physicians and patients need to weigh the potential benefits against the small risk of harm caused by transfusions."
For more on blood safety, visit the U.S. Food and Drug Administration.
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