Risk Factors for Transfusion in Elective EVAR and the Associated 30-day Clinical Outcomes
Nathan T. Orr, MD, Elliott H. Campbell, BSc., Eleftherios S. Xenos, MD/PhD, Daniel L. Davenport, PhD.
University of Kentucky, Lexington, KY, USA.
Objective:
This study characterizes the risk factors for transfusion and the 30-day clinical outcomes associated with perioperative blood transfusion during elective EVAR.
Methods:
A retrospective review of the American College of Surgeons National Surgery Quality Improvement Program (ACS NSQIP) was performed for elective EVAR cases with a primary indication for surgery documented as "aneurysm diameter". Excluded indications included non-ruptured symptomatic, rupture, unsatisfactory result from prior intervention, dissection, embolization, thrombosis, or unknown. Transfusion was defined as transfusion of red blood cells during or within 72 hours of the operation. All preoperative, intraoperative, and outcome variables were compared between transfused and non-transfused patients. We used propensity scoring to match transfused with non-transfused patients according to primary CPT code, renal function and creatinine, ASA class, age, gender, hematocrit, functional status, COPD, aneurysm size, proximal aneurysm extent, and duration of the operation. Thirty-day outcomes were compared between these clinically matched groups.
Results:
A total of 4568 elective EVAR cases were extracted from the database, of which, 347 (7.6%) received a perioperative transfusion. Preoperative risk factors for transfusion included female gender, increasing age, lower BMI, ASA class IV or V, nursing home residence or functional impairment, acute renal failure or dialysis, severe COPD, untreated hypertension, and bleeding disorders. Preoperative laboratory values that predicted transfusion included hematocrit <30%, platelets >400,000, BUN >40, creatinine >1.2, and albumin <3.0. Intraoperative risk factors for transfusion included attempted percutaneous converted to femoral cutdown, acute conversion to open aortic repair, duration of the operation, aneurysm diameter, proximal aneurysm extent, and concomitant renal stent placement, lower extremity revascularization, or access vessel procedures. The propensity matched 30-day outcomes are demonstrated in the table. Significantly worse outcomes were identified with transfusion, including a higher likelihood to return to the operating room, increased cardiac or respiratory failure, and increased renal complications. Median ICU stay and hospital stay were significantly longer for the cases requiring transfusion.
Conclusions:
A total of 7.6% of elective EVAR cases required transfusion resulting in a significantly increased 30-day mortality and morbidity. Modifiable risk factors for transfusion should be optimized preemptively to avoid the increased risks associated with transfusion in elective cases.
| Non-transfused | Transfused | P-value | |
| No. of Procedures | 592 | 296 | |
| %30-day mortality | 0.8 (n=5) | 3.7 (n=11) | 0.005 |
| %30-day morbidity | 13.9 | 24.7 | <0.001 |
| %Returned to the OR | 3.9 | 11.5 | <0.001 |
| %Cardiac or respiratory failure | 2.0 | 10.8 | <0.001 |
| %Renal insufficiency or failure | 0.7 | 4.4 | <0.001 |
| Median ICU stay, days (IQR) | 2 (1-3) | 3 (2.5) | <0.001 |
| Median length of hospital stay, days (IQR) | 0 (0-1) | 0 (0-2) | <0.001 |
| %Discharged home | 90.2 | 79.1 | <0.001 |
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