Red blood cell transfusion associated with increased morbidity and mortality in patients undergoing elective open abdominal aortic aneurysm repair

Abstract

Background: Red blood cell (RBC) transfusions are associated with increased mortality and morbidity. The aim of this analysis was to examine the association between RBC transfusions and long-term survival for patients undergoing elective open infrarenal abdominal aortic aneurysm (AAA) repair with up to 15 years of follow-up.

Methods: Prospective cohort study using data from The Danish Vascular Registry from 2000-2015. Primary endpoint was all-cause mortality. Secondary endpoints were in-hospital complications. Transfused patients were divided into subgroups based on received RBC transfusions (1, 2-3, 4-5 or > 5). Using Cox regression multi-adjusted analysis, non-transfused patients were compared to transfused patients (1, 2-3, 4-5, >5 transfusions) for both primary and secondary endpoints.

Results: There were 3 876 patients included with a mean survival of 9.1 years. There were 801 patients who did not receive transfusions. Overall 30-day mortality was 3.1% (121 patients) and 3.6% (112) for all transfused patients. For the five subgroups 30-day mortality was: No transfusions 1.1% (9 patients), 1 RBC 1.2% (4 patients), 2-3 RBC 2.2% (26 patients), 4-5 RBC 1.9% (14 patients) and > 5 RBC 7.9% (68 patients). After receiving RBCs, the hazard ratio for death was 1.54 (95% CI 1.27-1.85) compared to non-transfused patients. There was a significant increase in mortality when receiving 2-3 RBC: HR 1.32 (95% CI 1.07-1.62), 4-5 RBC: 1.64 (1.32-2.03) and >5 RBC: 1.96 (1.27-1.85) in a multi-adjusted model.

Conclusion: There is a dose-dependent association between RBC transfusions received during elective AAA repair and an increase in short- and long-term mortality. Approximately 25% of included patients had preoperative anemia. These findings should raise awareness regarding potentially unnecessary and harmful RBC transfusions.

Fig 1. Flow chart of patient selection process with excluded and included patients.

Data were retrieved from The Danish Vascular Registry during the period of January 1, 2000 to December 31, 2014. AAA: abdominal aortic aneurysm.

Fig 2. Development in transfusions and blood loss during 15-year follow-up period.

Upper left: Mean blood loss (mL) per patient across time. Upper right Mean number of transfusions per patient across time. Lower: Development in transfusions and blood loss from January 1, 2000 to December 31, 2014. P value calculated with year 2000 as reference.

Fig 3. Hazard ratio (95% CI) for mortality, all transfused patients and dose-dependent subgroups compared to non-transfused patients (reference group).

Above: Forest plot based on HR in table below Forest plot. Model I: Adjusted for age and gender. Model II: Adjusted for all baseline variables and characteristics (gender, age, preoperative hemoglobin and creatinine, bleeding, BMI, smoking, diabetes, hypertension, cerebrovascular, cardiac and respiratory disease). * P value < 0.05. ** P value < 0.01. *** P value < 0.001. The Kaplan-Meier plot shows a significant difference in survival between the non-transfused vs. transfused group, log rank p < 0.00001 (Fig 4).

Fig 4. Kaplan-Meier survival curves for patients undergoing open repair.

Data are stratified by number of received transfusions (0, 1–2, 2–3, 4–5 or >5) (left) or by transfused or non-transfused patients (right). Follow-up is shown for up to 10 years after aortic repair.