TORONTO — A new study suggests freshly donated blood is not better than older blood when it is transfused into severely ill patients.

The findings appear to disprove the belief that patients transfused with older blood have worse outcomes.

The researchers randomly assigned intensive care patients to receive blood that had been collected within the previous seven days or older blood, which in many cases had been in the blood bank for about three weeks.

The scientists hypothesized that those who received the fresher blood would do better, because studies in animals have suggested that could be true.

But instead, they found no difference in death rates, length of hospital stay or other important health measures.

The work was led by Canadian researchers and was funded by the Canadian Institutes of Health Research. It was published online Tuesday by the New England Journal of Medicine.