NEW YORK (Reuters Health) – Allogeneic blood transfusions in patients who undergo coronary artery bypass graft surgery (CABG) substantially increase the patient’s odds of nosocomial infection, hospital readmission within 30 days and mortality, the results of a recent cohort study propose.
What’s more, the variability in infection sites throughout the body implies that allogeneic blood causes a systemic immunosuppressive effect in the recipient, lead researcher Dr. Mary A. M. Rogers and colleagues suggest in BMC Medicine, posted online on July 30.
To assess the link between transfusion and patient outcomes, and to compare transfusion use and infection rates among hospitals, the researchers analyzed data for 24,789 Medicare beneficiaries who underwent CABG in a Michigan hospital from 2003 to 2006.
Only 19% of subjects did not receive an allogeneic transfusion, the report indicates. An infection during hospitalization occurred among 18.0% of patients who received allogeneic transfusions, 9.7% in those transfused with autologous blood only, and 6.6% among those not transfused (p < 0.001).
Allogeneic transfusion, but not autogenic transfusion, was significantly more likely to be associated with infections of the genitourinary system, respiratory tract, bloodstream, digestive tract and skin. Infections with Clostridium difficile were also noted.
For the majority of patients who underwent elective surgery, compared with patients who received no transfusions, allogenic transfusion was associated with odds ratios of 1.98 for in-hospital infection, 4.67 for in-hospital mortality, 1.43 for 30-day readmission to hospital (p < 0.001 for all three), and 2.88 for 30-day post-discharge mortality (p = 0.005). However, autologous transfusion was not associated with significantly increased rates in any of the outcomes.
Similar patterns were documented for urgent or emergency surgery.
The data showed sizable variation among hospitals in the use of allogeneic blood, ranging from 50% to 100% in men, and from 73% to 100% in women. Infection rates across hospitals ranged from 4% to 43%. Mean length of hospital stay was 9 days among patients who received a transfusion and 6 days among those who did not (p < 0.001).
“Overall, 30% of the variability in transfusion practices after CABG surgery was attributable to hospital site,” Dr. Rogers, from the University of Michigan, and her team report.
They estimate that for each 1% increase in hospital transfusion rates, predicted infection rates rose by 0.13%. The authors cite recent research that has implicated lengthy storage of red blood cells, with significantly higher rates of sepsis and mortality for cells stored for longer than 2 weeks.
Patient safety can improve, the team concludes, “if hospitals carefully review current guidelines on allogeneic blood transfusion, closely adhere to such guidelines, and institute interventions to reduce inappropriate use of blood transfusions in recipients of CABG.
BMC Med 2009.