Do Jehovah Witnesses have it right after all? Most people think that their refusal to use blood transfusions for religious reasons borders on insanity. But now research has shown that more than half of blood transfusions do more harm than good, with patients facing as much as a six-fold danger of dying. The problem is not the risk of infections from contaminated blood, but the transfusion itself. "There is virtually no high-quality study in surgery, or intensive care or acute care, outside of when you are bleeding to death, that shows that blood transfusion is beneficial," says cardiac surgeon Gavin Murphy, at the Bristol Heart Institute in the UK. And now the National Institutes of Health in the US has launched a review into the safety of transfusion. "Probably 40% to 60% of blood transfusions are not good for the patients," says Bruce Spiess, of Virginia Commonwealth University.

What is the take-home lesson from the demolition of a universally acknowledged truth? New Scientist editorialises that "Surgeons must bring science to bear to ensure their techniques really are having the desired effect. The revelations about the dangers of blood transfusions are a stark reminder that in medicine there is no substitute for evidence." ~ New Scientist, Apr 26; Guardian, Apr 24