Association of red blood cell transfusion and short- and longer-term mortality after coronary artery bypass graft surgery

Objective: Red blood cell (RBC) transfusion has been linked to increased morbidity and mortality. However, strict RBC transfusion recommendations recently have been questioned. The aim of this study was to investigate the short- and long-term mortality outcomes after RBC transfusion in patients undergoing coronary artery bypass graft surgery (CABG).

Design: This was a retrospective medical record review.

Setting: Tertiary care academic medical center.

Participants: The study included patients who underwent CABG from June 2006 to May 2013.

Intervention: Adult (>18 years) cardiac surgery patients who were admitted to the cardiothoracic intensive care unit in a tertiary care academic medical center from June 2006 to May 2013 were collected. In all, 2,180 patients who underwent CABG surgery were included into propensity-score matching analyses, which were matched 1:1. Patients who did not receive transfusion of packed red blood cells (PRBC) (n = 937) were compared with those who received 1 to 5 U (n = 1,113). The study outcomes included mortality rates at 1, 3, and 6 months (short-term) and 1, 2, 3, and 4 years (long-term).

Results: No statistical significant differences were found for the 1-month (2% v 1.1%, p = 0.292), 3-month (2.9% v 2%, p = 0.396), or 6-month mortality rate (4.3% v 3.4%, p = 0.602) in 446 patients with 1 to 5 U versus 446 matched patients with no PRBC transfusion. Patients in the transfused group compared with those in the no-transfusion group had statistically significant higher 3-year mortality rate (11% v 6.7%; hazard ratio, 1.64; 95% confidence interval, 1.03-2.63; p = 0.038).

Conclusion: In the present study, patients undergoing CABG surgery and receiving <6 U of PRBC did not have statistically increased risk for in-hospital mortality and up to 2 years postoperatively. A modestly statistically significant difference was noted at 3 years. However, cumulatively, there was no statistical difference between the transfused and nontransfused groups at 4 years. Further studies are needed to confirm the findings and define the population that will benefit the most from blood transfusion.