Tired blood

The common practice of storing blood for more than two weeks could be proving fatal for thousands of heart surgery patients, according to a major study.

Doctors at the Cleveland Clinic in Ohio have found that patients who receive blood that is more than 14 days old are nearly two-thirds more likely to die than those who get newer blood.

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A total of 2,872 patients received blood that had been stored for 14 days or less, and 3,130 patients received blood that was more than 14 days old.

The mean storage age was 11 days for the newer blood and 20 days for the older blood.

In-hospital mortality was significantly higher among those who received older blood: 2.8% compared to 1.7%.

The researchers also found that death rates a year on were nearly half as high again in the patients who had received older blood, compared to those who received newer blood. 11% of the patients who had received older blood had died a year later, compared to 7.4% of those who received newer blood. Both sets of patients received the same volume of blood.

The difference in hospital is 1.1% of all patients – not that much, but not insignificant either. A year later, the difference is 4.6% of all patients.  Nothing to sneeze at.

Really, this shouldn't be all that surprising.

Blood is not just one particular age.  Blood cells in the body are constantly being destroyed as they wear out, and constantly being replenished by new ones. Any batch of blood drawn from a donor is going to have some fraction of blood cells that are due for replacement, and that number will only increase as the blood ages.  It's like taking a bunch of people off a street corner in a big city.  Some fraction of those people will be retirement age.  If you hold the sample for ten years and don't allow reproduction, a larger fraction will be retirement age.

As usual, medicine involves weighing risks and benefits. A transfusion is always going to carry some risk.  If you need one right now, you need one.  If not, there are lots of good reasons not to get one.

And of course, if you're eligible to donate, please do so.

At least once a year, perhaps in honor of your birthday.