Blood safety measure seeks to prevent rare complication
Reported July 22, 2009
OTTAWA Canadian Blood Services has told 2,400 women that as of this week, they can no longer donate a blood component that is vital in treating cancer patients.
Platelets, fragile cell fragments found in whole blood that are essential to clotting, are in high demand, in part because they cannot be stored for more than a week. But in a letter sent earlier this month, Canadian Blood Services told its female platelet donors who have been pregnant even once that they can no longer give platelets because their donations may contain antibodies that trigger a rare, but potentially fatal, transfusion complication.
According to the blood agency, the chances of a transfusion recipient developing Transfusion Related Acute Lung Injury or TRALI are one in 5,000. Of those cases, five to 10 per cent will be fatal. In Canada, the health system identified as many as four cases a year where TRALI was a contributing factor to, but not necessarily the cause of, death.
Platelets are needed to treat patients with prolonged bleeding associated with some diseases. In particular, they are used to treat cancer patients whose bone marrow has been compromised either by the disease itself or by certain chemotherapy drugs, and can no longer produce platelets.
“The risk of not having a platelet transfusion when you need it is far greater than the risk of TRALI,” said Dr. Heather Hume, the executive medical director of transfusion medicine for Canadian Blood Services.
But the tainted-blood scandal that resulted when thousands of Canadians were infected with HIV or hepatitis C through transfusions in the 1980s and 1990s has led to better screening procedures of the blood supply, and much stricter rules on who is allowed to donate.
“Theres no doubt, as a worldwide community, we pay much greater attention to small risks than was the case 30 years ago” said Hume.
But, she added, just because the chances of a transfusion recipient developing TRALI are small, “that doesnt mean that we shouldnt try to do something to make it happen even less often.
“Weve tried to keep our supply up and decrease our risk of TRALI, but it is a constant balancing act.”
As of June, there were 6,768 platelet donors in Canada 2,400 of them women who have been pregnant at least once.
The chances of developing the harmful antibodies increases with each pregnancy, even if it ends prematurely. Studies have shown that after two pregnancies, one-quarter of women carry the potentially harmful antibodies.
But Hume said that these numbers dont tell the whole platelet supply story.
For one thing, 82 per cent of donations are from men, who give more frequently than women.
As well, women who have never been pregnant about one-third of all female donors can still donate.
That leaves a shortfall of 12 per cent of donations, “which is not insignificant,” said Hume. But some of the shortage has been made up with new technology that allows eligible donors to give a greater number of platelets in one sitting.
Canadian Blood Services has also been working to recruit more men to give platelets.
“We will be watching very carefully, but we are anticipating that it will not affect the supply,” said Hume.
Source : Canwest News Service
