Blood Stored Over 2 Weeks Linked to Risks After Heart Surgery

Transfusions of red blood cells stored for 15 days or more increase the risk of serious complications and both short- and long-term mortality following cardiac surgery, according to a retrospective study of more than 6,000 patients.

“The relative risk of postoperative death is increased by 30% in patients given blood that has been stored for more than 2 weeks,” wrote Dr. Colleen Gorman Koch and her colleagues at the Cleveland Clinic Foundation.

Earlier studies comparing older and newer blood have yielded conflicting results. These studies examined small or heterogeneous samples, did not control for confounding factors, and used end points that did not reflect specific organ function, such as length of hospital stay.

The present study analyzed data on 3,130 cardiac surgery patients transfused with 10,782 units of blood stored for more than 14 days and 2,872 patients transfused with 8,802 units of blood stored for 14 or fewer days during cardiac surgery at Cleveland Clinic between 1998 and 2006. It excluded patients whose transfusions consisted of both newer and older blood and those with trauma and chronic diseases. Patients underwent coronary artery bypass graft surgery, cardiac valve surgery, or both. The older and newer blood groups shared similarities on most baseline and operative variables. The primary end point was a composite of in-hospital adverse events defined by the Society of Thoracic Surgeons. Follow-up survival status was obtained from the Social Security Death Index (N. Engl. J. Med. 2008;358:1229–39).

The study found a significant association between blood storage time and the serious adverse events composite end point, which occurred in 22.4% of the patients who received newer blood and 25.9% of those who received older blood. The link remained after adjusting for coexisting conditions and other risk factors. Patients transfused with older blood, compared with those who received newer blood, had significantly higher rates of in-hospital mortality (2.8% vs. 1.7%), prolonged ventilation (9.7% vs. 5.6%), renal failure (2.7% vs. 1.6%), septicemia or sepsis (4.0% vs. 2.8%), and multisystem organ failure (0.7% vs. 0.2%).

Risk of death was significantly lower among patients who received newer units of blood; 1-year death rates were 7.4% and 11.0% for the newer and older blood groups, respectively.

The mortality increase with older blood was most pronounced within 6 months of surgery. “The adverse effects of transfusing older blood persisted even after adjustment for perioperative factors known to be associated with an adverse outcome in this population,” the researchers wrote (data were not presented). Further study is needed before any broad-based changes in blood banking practices are made, they said. The study's results, while important, are not enough to change blood supply practices, said Dr. John W. Adamson of the University of California, San Diego, in an accompanying editorial. Because the study population had a median age of 70 years, “by definition, the patients had a substantial number of coexisting illnesses.”

Transfusions of red blood cells stored for 15 days or more increase the risk of serious complications and both short- and long-term mortality following cardiac surgery, according to a retrospective study of more than 6,000 patients.

“The relative risk of postoperative death is increased by 30% in patients given blood that has been stored for more than 2 weeks,” wrote Dr. Colleen Gorman Koch and her colleagues at the Cleveland Clinic Foundation.

Earlier studies comparing older and newer blood have yielded conflicting results. These studies examined small or heterogeneous samples, did not control for confounding factors, and used end points that did not reflect specific organ function, such as length of hospital stay.

The present study analyzed data on 3,130 cardiac surgery patients transfused with 10,782 units of blood stored for more than 14 days and 2,872 patients transfused with 8,802 units of blood stored for 14 or fewer days during cardiac surgery at Cleveland Clinic between 1998 and 2006. It excluded patients whose transfusions consisted of both newer and older blood and those with trauma and chronic diseases. Patients underwent coronary artery bypass graft surgery, cardiac valve surgery, or both. The older and newer blood groups shared similarities on most baseline and operative variables. The primary end point was a composite of in-hospital adverse events defined by the Society of Thoracic Surgeons. Follow-up survival status was obtained from the Social Security Death Index (N. Engl. J. Med. 2008;358:1229–39).

The study found a significant association between blood storage time and the serious adverse events composite end point, which occurred in 22.4% of the patients who received newer blood and 25.9% of those who received older blood. The link remained after adjusting for coexisting conditions and other risk factors. Patients transfused with older blood, compared with those who received newer blood, had significantly higher rates of in-hospital mortality (2.8% vs. 1.7%), prolonged ventilation (9.7% vs. 5.6%), renal failure (2.7% vs. 1.6%), septicemia or sepsis (4.0% vs. 2.8%), and multisystem organ failure (0.7% vs. 0.2%).

Risk of death was significantly lower among patients who received newer units of blood; 1-year death rates were 7.4% and 11.0% for the newer and older blood groups, respectively.

The mortality increase with older blood was most pronounced within 6 months of surgery. “The adverse effects of transfusing older blood persisted even after adjustment for perioperative factors known to be associated with an adverse outcome in this population,” the researchers wrote (data were not presented). Further study is needed before any broad-based changes in blood banking practices are made, they said. The study's results, while important, are not enough to change blood supply practices, said Dr. John W. Adamson of the University of California, San Diego, in an accompanying editorial. Because the study population had a median age of 70 years, “by definition, the patients had a substantial number of coexisting illnesses.”

Transfusions of red blood cells stored for 15 days or more increase the risk of serious complications and both short- and long-term mortality following cardiac surgery, according to a retrospective study of more than 6,000 patients.

“The relative risk of postoperative death is increased by 30% in patients given blood that has been stored for more than 2 weeks,” wrote Dr. Colleen Gorman Koch and her colleagues at the Cleveland Clinic Foundation.

Earlier studies comparing older and newer blood have yielded conflicting results. These studies examined small or heterogeneous samples, did not control for confounding factors, and used end points that did not reflect specific organ function, such as length of hospital stay.

The present study analyzed data on 3,130 cardiac surgery patients transfused with 10,782 units of blood stored for more than 14 days and 2,872 patients transfused with 8,802 units of blood stored for 14 or fewer days during cardiac surgery at Cleveland Clinic between 1998 and 2006. It excluded patients whose transfusions consisted of both newer and older blood and those with trauma and chronic diseases. Patients underwent coronary artery bypass graft surgery, cardiac valve surgery, or both. The older and newer blood groups shared similarities on most baseline and operative variables. The primary end point was a composite of in-hospital adverse events defined by the Society of Thoracic Surgeons. Follow-up survival status was obtained from the Social Security Death Index (N. Engl. J. Med. 2008;358:1229–39).

The study found a significant association between blood storage time and the serious adverse events composite end point, which occurred in 22.4% of the patients who received newer blood and 25.9% of those who received older blood. The link remained after adjusting for coexisting conditions and other risk factors. Patients transfused with older blood, compared with those who received newer blood, had significantly higher rates of in-hospital mortality (2.8% vs. 1.7%), prolonged ventilation (9.7% vs. 5.6%), renal failure (2.7% vs. 1.6%), septicemia or sepsis (4.0% vs. 2.8%), and multisystem organ failure (0.7% vs. 0.2%).

Risk of death was significantly lower among patients who received newer units of blood; 1-year death rates were 7.4% and 11.0% for the newer and older blood groups, respectively.

The mortality increase with older blood was most pronounced within 6 months of surgery. “The adverse effects of transfusing older blood persisted even after adjustment for perioperative factors known to be associated with an adverse outcome in this population,” the researchers wrote (data were not presented). Further study is needed before any broad-based changes in blood banking practices are made, they said. The study's results, while important, are not enough to change blood supply practices, said Dr. John W. Adamson of the University of California, San Diego, in an accompanying editorial. Because the study population had a median age of 70 years, “by definition, the patients had a substantial number of coexisting illnesses.”