Cath Lab Digest

Abstract

Background. Worse outcomes in transfused patients have been observed in various settings, but little is known about the significance of RBC transfusion in patients with peripheral arterial disease. We queried the NSQIP database to examine the effect of intraoperative blood transfusion on the morbidity and mortality in patients who underwent lower-extremity revascularization.
Methods. We analyzed the data from the Participant Use Data File containing vascular surgical cases submitted to the ACS NSQIP in 2005, 2006 and 2007. CPT-4 codes were used to select lower-extremity revascularization procedures. Thirty-day outcomes analyzed were: 1) mortality; 2) composite morbidity; 3) graft/prosthesis failure; 4) return to the operating room for any reason within 30 days; 5) wound occurrences; 6) sepsis or septic shock; 7) pulmonary occurrences; and 8) renal insufficiency or failure. Outcome rates were compared between the transfused and non-transfused groups using the chi² test. Patients were ranked into five equal-sized groups (quintiles) based on their transfusion propensity.
Results. The database contained 8,799 patients who underwent lower extremity revascularization between 2005 and 2007. Transfusion rates ranged from 4.4% in the lowest propensity quintile to 52.9% in the high propensity quintile. The mortality rate was significantly higher in transfused patients versus non-transfused (chi² < 0.05) for all but the lowest propensity quintile. After adjustment for transfusion propensity and patient and procedural risks, transfusion of 1 or 2 units remained significantly predictive of mortality, composite morbidity, sepsis/shock, pulmonary occurrences, renal insufficiency/failure and return to the operating room. Risks for these outcomes increased with level of transfusion. The adjusted odds ratios for 30-day mortality ranged from 1.92 (95% C.I. 1.36–2.70) for 1–2 units to 2.48 (95% C.I. 1.55–3.98) for 3 or more units.
Conclusion. In a large number of patients undergoing lower-extremity revascularization we have found that there is higher risk of postoperative mortality, pulmonary, renal and infectious complications after receiving intraoperative RBC transfusion. The risk for adverse outcomes increases with higher number of units transfused. Additional studies are necessary to better define transfusion triggers that balance the risk/benefit ratio for blood transfusion.

VASCULAR DISEASE MANAGEMENT 2010;7:E152–E156

Key words: lower limb; surgery; morbidity; mortality;
chronic ischemia

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Introduction

Red blood cell (RBC) transfusion is a common event in the perioperative course of patients undergoing lower-extremity revascularization. Worse outcomes in transfused patients have been observed in various settings including critically ill patients, elderly patients, cardiac surgery, trauma patients, orthopedic surgical patients and patients with acute coronary syndrome. Allogeneic transfusions have been associated with a higher risk of intensive care unit (ICU) admission, longer hospital and ICU stays, a higher postoperative infection rates, a higher risk of developing adult respiratory distress syndrome (ARDS), longer time to ambulation, a higher incidence of atrial fibrillation and a higher risk of ischemic outcomes compared with nontransfused cohorts.^1–5 We queried the National Surgical Quality Improvement Program (NSQIP) database to examine the effect of intraoperative blood transfusion on the morbidity and mortality in patients who underwent lower-extremity revascularization.

Methods

The American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) collects data on 135 variables including preoperative risk factors, intraoperative variables and 30-day postoperative morbidity and mortality outcomes for patients undergoing surgical procedures in both the inpatient and outpatient setting. We analyzed the data from the Participant Use Data File containing vascular surgical cases submitted to the ACS NSQIP in 2005, 2006 and 2007 by 173 hospitals throughout the United States. Primary procedure CPT-4® codes were used to select lower-extremity procedures, which were grouped into venous graft (CPT code 35533, 35541, 35546, 35556, 35558, 35565, 35566, 35571, 35583, 35585, or 35587); prosthetic graft (CPT code 35646, 35647, 35654, 35656, 35661, 35665, 35666, or 35671); or thromboendarterectomy (CPT code 35371, 35372 or 35381).

Intraoperative transfusion of packed red blood cells was categorized as: none, 1–2 units and ≥ 3 units. Outcome rates were compared between the transfused and nontransfused groups using the chi² test. Thirty-day outcomes analyzed were: 1) mortality; 2) composite morbidity (one or more of 21 adverse events uniformly defined by the ACS NSQIP); 3) graft/prosthesis failure; 4) return to the operating room for any reason within 30 days; 5) wound occurrences; 6) sepsis or septic shock; 7) pulmonary occurrences; and 8) renal insufficiency or failure. The risk (propensity) of intraoperative transfusion in this patient population was calculated using logistic regression of over 55 ACS NSQIP patient risk factors in a forward stepwise fashion (p for entry < 0.05, for exit > 0.10) followed by addition of the procedure group and complexity (Work RVUs). Patients were ranked into five equal-sized groups (quintiles) based on their transfusion propensity. Within each quintile, the numbers of transfused and nontransfused patients were counted and the mortality rates were compared using chi2 tests. The odds ratios (OR) by transfusion category were calculated for each of the outcomes using logistic regression.