By studying the data from more than 1,800 patients, once we had taken pre-morbid conditions into account, there was no evidence of a long-term effect of blood transfusion, told lead author Dr. William Weightman from the University of Western Australia, Perth, Western Australia.

Dr. Weightman and team reported that blood transfusion has been noted to have adverse effects on long-term health, primarily through immune modulation and tumor promotion.

To support the findings, the investigators studied the study outcomes of 1841 patients with mean age 62.7, who had first-time isolated non-emergency coronary artery surgery between 1993 and 2000 and survived longer than 60 days after surgery.

Out of all, 770 did not receive perioperative blood transfusions, 402 received 1 to 2 units of blood products, 333 received 3 to 6 units, and 327 received 6 or more units.

In the study, 266 patients died during a mean follow-up of 8.1 years (range 4.6-11.9 years).

Pre-existing conditions predictive of reduced long-term survival included older age, cerebrovascular disease, renal dysfunction, use of a mammary graft, chronic pulmonary disease, reduced left ventricular function, and preoperative anemia.

We didn’t see even a hint of an effect, Dr. Weightman said. Our hazard ratios were close to 1.0 right up to 6 donor exposures, and there was no suggestion of a dose-response effect.

In the patients who died during follow up, there was no link between blood transfusion and a cancer diagnosis at the time of death. In transfused patients 27% had a new cancer diagnosis at the time of death, compared with 43% of the patients who were not transfused.

Should a blood transfusion in cardiac surgery of up to 6 donor units be considered necessary, clinicians and patients can be reassured that we found no evidence of systematic adverse effects on health that were severe enough to reduce survival from 2 months post surgery to 10 years later, told Dr. Weightman.

It’s worth noting, he added, that this study was performed prior to the adoption of leukocyte depletion of blood products. It is plausible to speculate that now that we have universal leukocyte depletion that the safety of blood transfusion has increased, he said.