Blood transfusion is associated with increased morbidity and mortality after lower extremity revascularization
Article Outline
- Abstract
- Methods
- Results
- Discussion
- Author contributions
- Acknowledgment
- Appendices AI-AIII (online only)
- References
- Copyright
Background
Little is known about the significance of blood transfusion in patients with peripheral arterial disease. We queried the American College of Surgeons National Surgical Quality Improvement Program (ACS 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 data from the participant use data file containing vascular surgical cases submitted to the ACS NSQIP in 2005, 2006, and 2007 by 173 hospitals. Current procedural terminology codes were used to select lower extremity procedures that were grouped into venous graft, prosthetic graft, or thromboendarterectomy. Thirty-day outcomes analyzed were (1) mortality, (2) composite morbidity, (3) graft/prosthesis failure, (4) return to the operating room within 30 days, (5) wound occurrences, (6) sepsis or septic shock, (7) pulmonary occurrences, and (8) renal insufficiency or failure. Intraoperative transfusion of packed red blood cells was categorized as none, 1 to 2 units, and 3 or more units. Outcome rates were compared between the transfused and nontransfused groups using the χ2 test and multivariable regression adjusting for transfusion propensity, comorbid and procedural risk.
Results
A total of 8799 patients underwent lower extremity revascularization between 2005 and 2007. Mean age was 66.8 ± 12.0 years and 5569 (63.3%) were male. Transfusion rates ranged from 14.5% in thromboendarterectomy patients to 27.1% in prosthetic bypass patients (P < .05). 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, and return to the operating room. The adjusted odds ratios for 30-day mortality ranged from 1.92 (95% confidence interval [CI] 1.36-2.70) for 1 to 2 units to 2.48 (95% CI 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 a higher risk of postoperative mortality, pulmonary, and infectious complications after receiving intraoperative blood transfusion. Additional studies are necessary to better define transfusion triggers that balance the risk/benefit ratio for blood transfusion.
The population of patients with peripheral arterial disease (PAD) is steadily advancing in age, and older patients with multiple comorbid conditions undergo lower extremity revascularization. Red blood cell (RBC) transfusion is a common event in the perioperative course of these patients. This practice is not without risk. Worse outcomes in transfused patients have been observed in various settings such as critically ill patients, elderly patients, cardiac surgery/trauma/orthopedic surgical patients, and patients with acute coronary syndrome. In these studies, patients receiving allogeneic transfusions have had higher mortality rates, higher risk of intensive care unit (ICU) admission, longer hospital and ICU stays, higher postoperative infection rates, higher risk of developing adult respiratory distress syndrome (ARDS), longer time to ambulation, higher incidence of atrial fibrillation, and higher risk of ischemic outcomes compared with nontransfused cohorts.1, 2, 3, 4, 5, 6 Little is known about the significance of RBC transfusion in patients with PAD. 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
Study population
The American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) is a reporting system designed to provide reliable, risk-adjusted surgical outcomes data to surgical services and administrators at medical centers throughout the private sector so that surgical quality can be assessed and improved on a national level. 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.
Data collection
The ACS 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. Data are prospectively collected in a standardized fashion according to strict definitions by dedicated surgical clinical nurse reviewers. Patients are followed throughout their hospital course and after discharge from the hospital up to 30 days postoperatively. Nurse reviewers collect data from computerized and paper patient medical records, doctor's office records, and telephone interviews with patients. The accuracy and reproducibility of the data have been previously demonstrated.7, 8, 9 Primary procedure current procedural terminology (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). Thirty-day outcomes analyzed were (1) mortality, (2) composite morbidity (one or more of 21 adverse events uniformly defined by the ACS NSQIP, including all of the following subgroups), (3) graft/prosthesis failure (defined as “mechanical failure of an extra-cardiac graft or prosthesis
…
requiring return to the operating room, interventional radiology, or a balloon angioplasty.”), (4) return to the operating room for any reason within 30 days, (5) wound occurrences (superficial, deep or organ/space surgical site infection and/or wound dehiscence), (6) sepsis or septic shock, (7) pulmonary occurrences (ventilation greater than 48 hours, pneumonia and/or unplanned intubation), and (8) renal insufficiency or failure (defined as “the reduced capacity of the kidney to perform its function as evidenced by a rise in creatinine of >2 mg/dL from preoperative value, but with no requirement for dialysis”).
Intraoperative transfusion of packed RBCs was categorized as none, 1 to 2 units, and 3 or more units. Preoperative hematocrit is measured according to the value closest to the entry to the operating room. Outcome rates were compared between the transfused and nontransfused groups using the χ2 test. Significant P values for the multiple comparisons were adjusted to .005.
The risk (propensity) of intraoperative transfusion in this patient population was calculated using logistic regression of more than 55 ACS NSQIP patient risk factors in a forward stepwise fashion (P for entry <.05, for exit >.10) followed by the addition of procedure group and complexity (work relative value units [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 χ2 tests (P < .01 to correct for multiple comparisons). This was performed as a high-level omnibus test to aid in visualization prior to the more powerful multivariable analysis.
The odds ratios (ORs) by transfusion category were calculated for each of the outcomes using logistic regression (P < .005 was considered significant to correct for multiple comparisons). Adjusting variables included transfusion propensity, independent patient risk factors included in a forward stepwise fashion (P for entry <.05, for exit >.10), wound class, operative duration, procedure type, and complexity. Transfusion category was added at the end to the model. (Appendix Table AI, online only).
Results
The ACS NSQIP database contained 8799 patients who underwent lower extremity revascularization between 2005 and 2007. Their mean age was 66.8 ± 12.0 years and 5569 (63.3%) were male. Transfusion rates varied across procedure group, ranging from 14.5% in thromboendarterectomy patients to 27.1% in prosthetic bypass patients (χ2 P < .05, Table I).
Table I. Intraoperative transfusion rates and 30-day outcomes by type of lower extremity revascularization procedure
| Lower extremity revascularization procedure | n, % | Transfused % | Mortality % | Morbidity % |
|---|---|---|---|---|
| Bypass w/prosthetic | 3696, | 27.1 | 3.1 | 25.4 |
| Bypass w/vein | 4076, | 20.1 | 2.5 | 27.1 |
| Thromboendarterectomy | 1027, | 14.5 | 3.4 | 19.7 |
| Total | 8799, | 22.4 | 2.9 | 25.5 |
The amount of RBC units given by preoperative hematocrit (Hct) appears in Fig 1. The transfusion propensity model included 20 patient risk factors and three intraoperative risk factors (Appendix Table AI, online only). The 10 most significant predictors of transfusion in lower extremity revascularization patients, by order of entry into the model were (1) preoperative Hct, (2) procedure group and (3) complexity (work RVUs), (4) American Society of Anesthesiologists' physical status classification [ASA class], (5) general anesthesia versus other, (6) prior coronary intervention, (7) emergent status, (8) age, (9) alkaline phosphatase greater than 125 U/L, and (10) serum albumin (g/dL, inverse relationship).

Fig 1.
Mean number of units of packed red blood cells given intraoperatively by preoperative hematocrit level. Lower extremity revascularization patients, n = 8799.
Transfusion rates ranged from 4.4% in the lowest propensity quintile to 52.9% in the high propensity quintile. The Mantel-Haenszel common odds ratio estimate across propensity quintiles was 2.13 (95% confidence interval [CI], 1.61-2.81; P < .001). The Breslow-Day test did not support rejecting homogeneity (P = .288). The mortality rate was significantly higher in transfused patients versus nontransfused for the highest and low–middle quintiles (χ2 P < .01, Fig 2). Mortality was threefold overall in transfused patients (6.2% in transfused patients vs 1.9% in nontransfused). All unadjusted outcomes examined were significantly higher in transfused patients (χ2 P < .001, Table II).

Fig 2.
Mortality in transfused vs nontransfused patients within groups matched by their preoperative risk (propensity) of intraoperative transfusion. *χ2 P < .01.
Propensity is the estimated risk based on regression of preoperative hematocrit, procedure type and complexity, ASA class, emergent status, age, and 18 other risk factors vs whether or not the patient received a transfusion intraoperatively. The propensity regression model is in the Appendix.
Table II. Thirty-day outcomes for lower extremity revascularization patients transfused intraoperatively vs not
| Outcome | Not transfused | Transfused | χ2P value | Propensity and risk-adjusteda transfusion odds ratio (95% CI) | Wald P value across categories | |
|---|---|---|---|---|---|---|
| 6827, | 1971, | 1-2 u. | 3+ u. | |||
| Mortality, % | 1.9 | 6.2 | <.001 | 1.92 | 2.48 | <.001 |
| Morbidity, % | 21.7 | 38.8 | <.001 | 1.37 | 1.81 | <.001 |
| 30-d graft failure, % | 4.8 | 7.8 | <.001 | 1.28 | 1.09 | .151 |
| Return to OR, % | 15.4 | 26.8 | <.001 | 1.29 | 1.35 | .002 |
| Wound occurrence,b % | 10.5 | 14.4 | <.001 | 1.20 | 1.33 | .059 |
| Sepsis/shock, % | 5.0 | 12.9 | <.001 | 1.41 | 2.11 | <.001 |
| Pulmonary occurrence,c % | 3.5 | 14.5 | <.001 | 2.23 | 3.68 | <.001 |
| Renal insufficiency/failure, % | 1.0 | 3.0 | <.001 | 1.17 | 2.44 | .009 |
aEach outcome regression model included transfusion propensity, all independently significant ACS NSQIP adjusting risk factors included in forward stepwise regression, procedure group and complexity, wound class, and operative duration with level of intraoperative transfusion added at the end. The mortality and overall morbidity models are shown in the Appendix. Others are not shown. |
bWound occurrences included superficial, deep and organ/space surgical site infection and wound dehiscence. |
cPulmonary occurrences included pneumonia, unplanned intubation, and ventilation greater than 48 hours. |
Each of the outcome multivariable regression models was highly significant in predicting each outcome (χ2 P < .001) and discrimination (c-indices) ranged from 0.66 (graft failure) to 0.85 (mortality). The mortality and composite morbidity models are shown in the Appendix Table AII, online only, Appendix Table AIII, online only. After adjustment for transfusion propensity and patient and procedural risks, transfusion of 1 or 2 units remained significantly (P < .005) predictive of mortality, composite morbidity, sepsis/shock, pulmonary occurrences, and return to the operating room. Risks for these outcomes increased with level of transfusion (Table II), although the significance of the increase was not determined. The adjusted odds ratios for 30-day mortality ranged from 1.92 (95% CI, 1.36-2.70) for 1 to 2 units to 2.48 (95% CI, 1.55-3.98) for 3 or more units (Wald P < .001).
Discussion
Blood product transfusion is a common event during peripheral vascular operations with the goal of replacing volume and increasing blood oxygen carrying capacity.10 Dramatic improvements in reduction of transmission of infectious agents11, 12 have led to new and increased focus on other serious hazards of transfusion such as multiple system organ failure associated with cytokine release, bacterial contamination, sepsis, metabolic disturbances, circulatory overload, hemolytic reactions, and risk of old blood.
After removal from the body and with the added effect of storage, RBCs undergo changes (many irreversible) that adversely affect their viability and function. These adverse changes include oxidation and rearrangement of lipids, loss of proteins, and depletion of ATP and 2, 3-diphosphoglycerate. In storage, RBCs continuously lose their membrane through shedding vesicles and become rigid. Moreover, during storage, bioactive by-products and ions (hemoglobin, lipids, and potassium)—some with proinflammatory effects—are released from RBCs and accumulate in blood units whereby they can cause adverse reactions in a recipient. These changes are collectively called “storage lesion.” Transfusion of blood that is stored for prolonged periods (but still within the currently accepted maximum allowed storage time of 42 days) has been linked to increased risk of complications and reduced survival in patients undergoing cardiac surgery and in other patient populations.13, 14, 15, 16, 17
Studies in cardiac surgery patients associated transfusion with increased mortality, higher incidence of postoperative infection, prolonged respiratory support, higher risk of postoperative infection, and higher risk of renal failure.4, 8 Similarly, in critical care patients, transfusion has been associated with increased overall and ICU 14-day mortality rate, higher 28-day mortality rate, longer length of stay, higher risk of developing ARDS, and higher incidence of bloodstream infections.18, 19, 20, 21, 22
We focused on the risks of blood transfusion in patients following peripheral vascular operations and using the NSQIP database examined 30-day morbidity and mortality. Our data suggest that after risk adjustment, patients receiving intraoperative transfusion are at higher risk of developing morbidity and mortality.
Transfusion-associated lung injury (TRALI) is a well recognized complication and is considered to be the second leading cause of mortality from transfusion.23, 24 In our population, there was almost a threefold overall increase in the incidence of pulmonary complications in transfused patients, transfusion of 3 or more units carried an even higher risk as compared with 1 to 2 units. The pathophysiologic mechanisms of TRALI are incompletely understood and have been described as antibody-mediated and nonantibody-mediated. In both cases, activation of neutrophils plays a causal role, and these activated cells are thought to locally mediate pulmonary injury.25, 26
The threshold at which a patient receives a blood transfusion is arbitrary, depending on the culture of practice at various different institutions. The optimal range of hematocrit values that balances the associated complications of blood transfusion with complications related to anemia is unknown. Habib et al27 reported that the lowest hematocrit value on cardiopulmonary bypass (<22%) was associated with increased morbidity and was predictive of worse 0- to 6-year survival. Although Wu et al28 described a benefit for RBC transfusion in patients who were elderly and had low admission hematocrit values (<30%), they also reported that for those patients with hematocrit values of ≥36% and who received transfusions had a higher risk of death within 30 days than patients with a similar hematocrit who did not receive blood. In a randomized, controlled trial of 838 critically ill patients, Hebert29 reported similar overall 30-day mortality for a restrictive transfusion strategy (hemoglobin levels maintained between 7 and 9 g/dL) vs a more liberal strategy (hemoglobin levels maintained between 10 and 12 g/dL). Although mortality was similar in the two groups, it was significantly lower with the restrictive strategy among patients who were less acutely ill. Because we found that transfusion was not limited to patients with low Hct in our population, we carried out a propensity risk assessment based on preoperative Hct, procedure type and complexity, ASA class, emergent status, age, and 18 other risk factors vs whether or not the patient received a transfusion intraoperatively. The propensity regression showed that mortality is significantly higher in transfused vs nontransfused patients within groups matched by their preoperative risk (propensity) of intraoperative transfusion, even for low- and medium-propensity patients.
The immunologic effects of blood transfusion may be responsible for the observed increase in risk of infection in blood-transfused patients. Blood transfusions have been shown to be independent risk factor for infection.30, 31 Transfusion-related immunomodulation (TRIM) includes both alloimmunization of the host and immune activation as well as tolerance manifested as cancer recurrence, improved allograft survival, and higher rates of postoperative infections.32, 33 Leukoreduction may decrease postoperative infections,34 and today, most RBC transfusions in the US are leukoreduced; however, the cost-effectiveness of leukoreduction has yet to be proven, especially in low-risk populations.35
A limitation of our study is that the transfusion propensity was calculated based on preoperative hematocrit values possibly not accurately reflecting acute intraoperative blood loss. There are other factors not captured by the NSQIP database that can affect the outcome of the revascularization procedure as well as the need for intraoperative blood transfusion, including the skill and experience of the surgeon and technical difficulty of the procedure. We took into account in our propensity and risk models adjustment for operative duration, wound class, work RVUs, emergency status, and use of preoperative transfusion, which capture some of the variation due to skill and difficulty.
To conclude, our study in a large number of patients undergoing lower extremity revascularization indicates that allogeneic intraoperative transfusion is associated with higher postoperative morbidity and mortality. This finding is true after adjusting for propensity for transfusion, thus, the reason that transfused patients do poorly is not because they have a lower preoperative hematocrit. When do the risks of anemia outweigh the hazards of transfusion? In the absence of acute bleeding, hemoglobin levels consistent with the TRICC trial (7.0-9.0 g/dL) are well tolerated.29 There is little evidence that RBC transfusion in the nonbleeding patient with a hemoglobin concentration greater than 7.0 g/dL leads to improved outcome. Clinicians should use hemodynamic and physiologic parameters such as blood pressure, heart rate, and urine output in conjunction with hemoglobin levels to decide whether a patient needs to be transfused.
Additional prospective randomized studies are required to determine the risk/benefit of RBC transfusion in various disease states, the optimal transfusion trigger, and the effects of blood storage time and leukodepletion on clinical outcomes.
Author contributions
The American College of Surgeons National Surgical Quality Improvement Program and the hospitals participating in the ACS NSQIP are the source of the data used herein; they have not verified and are not responsible for the statistical validity of the data analysis or the conclusions derived by the authors.
Appendices AI-AIII (online only)
Appendix Table AI, online only. Transfusion regression model, c-index = 0.79
| Entry order | Variables in the equation | Odds ratio | 95% CI OR | Sig. | |
|---|---|---|---|---|---|
| Lower | Upper | ||||
| 1 | Preop hematocrit vs >48% | .000 | |||
| 23.026 | 11.439 | 46.353 | .000 | ||
| 18.633 | 10.941 | 31.731 | .000 | ||
| 8.423 | 5.110 | 13.884 | .000 | ||
| 4.165 | 2.545 | 6.816 | .000 | ||
| 2.454 | 1.506 | 3.998 | .000 | ||
| 1.854 | 1.133 | 3.033 | .014 | ||
| 1.362 | .809 | 2.293 | .245 | ||
| 2 | Procedure vs thromboendarterectomy | .000 | |||
| .889 | .703 | 1.125 | .329 | ||
| .349 | .269 | .453 | .000 | ||
| 3 | Work RVUs | 1.148 | 1.133 | 1.164 | .000 |
| 4 | ASA class vs 1 | .000 | |||
| .276 | .115 | .664 | .004 | ||
| .457 | .198 | 1.055 | .066 | ||
| .609 | .262 | 1.418 | .250 | ||
| .594 | .170 | 2.072 | .414 | ||
| 5 | General anesthetic vs other | 2.267 | 1.810 | 2.838 | .000 |
| 6 | Prior coronary intervention | 1.448 | 1.283 | 1.634 | .000 |
| 7 | Emergency status | 1.626 | 1.329 | 1.990 | .000 |
| 8 | Age | 1.010 | 1.005 | 1.015 | .000 |
| 9 | Alkaline phosphatase >125 | 1.523 | 1.237 | 1.875 | .000 |
| 10 | Serum albumin | 1.390 | 1.236 | 1.563 | .000 |
| 11 | Known bleeding disorder | 1.228 | 1.078 | 1.399 | .002 |
| 12 | Functional status vs independent | .004 | |||
| 1.292 | 1.109 | 1.505 | .001 | ||
| 1.191 | .840 | 1.689 | .326 | ||
| 13 | Platelets <150 | 1.412 | 1.153 | 1.727 | .001 |
| 14 | Male vs female | .806 | .716 | .907 | .000 |
| 15 | PT >13.2 | 1.183 | 1.052 | 1.331 | .005 |
| 16 | Prior periph. vasc. procedure | 1.178 | 1.049 | 1.323 | .006 |
| 17 | Hx CHF, AMI or angina | 1.303 | 1.062 | 1.600 | .011 |
| 18 | Diabetes vs not treated | .019 | |||
| .833 | .713 | .972 | .021 | ||
| .844 | .725 | .984 | .030 | ||
| 19 | Platelets >400 | 1.275 | 1.049 | 1.548 | .015 |
| 20 | Preop transfusion >4 u. RBCs | 2.657 | 1.122 | 6.288 | .026 |
| 21 | EtOH >2 drinks/day | 1.276 | 1.016 | 1.603 | .036 |
| 22 | Preop renal failure | .566 | .343 | .934 | .026 |
| 23 | BUN >40 | 1.261 | 1.018 | 1.561 | .034 |
| Constant | .000 | .000 | |||
Appendix Table AII, online only. Mortality regression model, c-index = 0.853
| Step | Variable | Sig. | Odds ratio | 95% CI | |
|---|---|---|---|---|---|
| Lower | Upper | ||||
| Forced | Transfusion propensity | .073 | .434 | .174 | 1.082 |
| Functional status vs independent | |||||
| .001 | 1.732 | 1.254 | 2.392 | ||
| .019 | 1.966 | 1.120 | 3.451 | ||
| On dialysis | <.001 | 3.003 | 2.067 | 4.363 | |
| Age | <.001 | 1.047 | 1.033 | 1.061 | |
| Emergency | <.001 | 2.061 | 1.405 | 3.025 | |
| ASA class vs 1 | <.001 | Sig. across all values | |||
| .754 | .692 | .069 | 6.926 | ||
| .585 | .544 | .061 | 4.846 | ||
| .934 | 1.097 | .123 | 9.772 | ||
| .719 | 1.564 | .137 | 17.841 | ||
| Serum albumin | .008 | .736 | .587 | .922 | |
| BMI categ. Kg/m2 vs 18.5-25 | |||||
| .003 | 2.018 | 1.260 | 3.231 | ||
| .184 | .805 | .585 | 1.108 | ||
| .030 | .586 | .362 | .949 | ||
| .032 | .376 | .154 | .922 | ||
| .963 | .979 | .403 | 2.380 | ||
| Hx cardiovasc. disease | .003 | 1.740 | 1.200 | 2.523 | |
| BUN >40 | .001 | 1.938 | 1.325 | 2.836 | |
| Bilirubin >1.0 | .002 | 2.194 | 1.342 | 3.587 | |
| Systemic inflammation vs none | |||||
| .009 | 1.747 | 1.152 | 2.650 | ||
| .376 | .638 | .236 | 1.725 | ||
| .137 | 1.923 | .813 | 4.548 | ||
| Male vs female | .010 | .691 | .522 | .915 | |
| Coma >24 hours postop | .016 | 12.461 | 1.610 | 96.442 | |
| Pulmonary compromise | .025 | 1.464 | 1.050 | 2.041 | |
| Forced | Wound class vs clean | ||||
| .362 | 1.424 | .666 | 3.046 | ||
| .506 | 1.192 | .711 | 1.997 | ||
| .081 | 1.630 | .941 | 2.824 | ||
| Forced | Operative duration minutes | .027 | 1.002 | 1.000 | 1.003 |
| Forced | Procedure type vs thromboendart. | ||||
| .296 | .765 | .463 | 1.265 | ||
| .020 | .488 | .267 | .893 | ||
| Forced | Work RVUs | .052 | 1.040 | 1.000 | 1.082 |
| Forced | Intraop transfusion vs none | ||||
| <.001 | 1.919 | 1.362 | 2.704 | ||
| <.001 | 2.482 | 1.548 | 3.978 | ||
| <.001 | .001 | ||||
Appendix Table AIII, online only. Morbidity regression model, c-index = 0.70
| Step | Variable | Sig. | Odds ratio | 95% CI | |
|---|---|---|---|---|---|
| Lower | Upper | ||||
| Forced | Transfusion propensity | .685 | .921 | .618 | 1.372 |
| Functional status vs independent | |||||
| <.001 | 1.478 | 1.284 | 1.702 | ||
| <.001 | 2.202 | 1.585 | 3.057 | ||
| Systemic inflammation vs none | |||||
| <.001 | 1.673 | 1.353 | 2.069 | ||
| .060 | 1.465 | .984 | 2.180 | ||
| .121 | 1.740 | .863 | 3.507 | ||
| BMI categ. Kg/m2 vs 18.5-25.0 | |||||
| .752 | .959 | .739 | 1.245 | ||
| .239 | 1.078 | .951 | 1.222 | ||
| <.001 | 1.440 | 1.239 | 1.674 | ||
| <.001 | 1.697 | 1.373 | 2.096 | ||
| .009 | 1.474 | 1.104 | 1.969 | ||
| Rest pain | <.001 | 1.294 | 1.165 | 1.437 | |
| ASA class vs 1 | <.001 | Sig. across all values | |||
| .146 | .538 | .233 | 1.241 | ||
| .290 | .646 | .287 | 1.452 | ||
| .723 | .863 | .382 | 1.951 | ||
| .546 | 1.452 | .432 | 4.877 | ||
| Emergency | <.001 | 1.650 | 1.366 | 1.994 | |
| Male vs female | <.001 | .755 | .678 | .840 | |
| Pulmonary compromise | .001 | 1.265 | 1.098 | 1.457 | |
| Hx stroke/TIA | .004 | 1.206 | 1.061 | 1.371 | |
| SGOT >40 | .007 | 1.333 | 1.082 | 1.643 | |
| Creatinine >1.2 | .002 | 1.189 | 1.063 | 1.330 | |
| PT >13.2 | .002 | 1.187 | 1.065 | 1.324 | |
| Sodium <135 | .006 | 1.230 | 1.061 | 1.426 | |
| CNS tumor | .037 | 6.103 | 1.119 | 33.294 | |
| Hx cardiovascular disease | .003 | 1.334 | 1.104 | 1.611 | |
| Recent 10% weight loss | .031 | 1.461 | 1.035 | 2.062 | |
| Preop transfusion 5+ u. | .028 | 2.572 | 1.105 | 5.988 | |
| Forced | Wound class vs clean | .019 | |||
| .074 | 1.300 | .975 | 1.733 | ||
| .059 | 1.245 | .992 | 1.562 | ||
| .103 | .797 | .607 | 1.047 | ||
| Forced | Operative duration minutes | <.001 | 1.002 | 1.001 | 1.003 |
| Forced | Procedure type vs thrombo endarterectomy | .401 | |||
| .180 | 1.152 | .937 | 1.416 | ||
| .305 | 1.129 | .895 | 1.425 | ||
| Forced | Work RVUs | .004 | 1.022 | 1.007 | 1.037 |
| Forced | Intraop transfusion vs none | ||||
| <.001 | 1.369 | 1.188 | 1.577 | ||
| <.001 | 1.812 | 1.463 | 2.243 | ||
| <.001 | .090 | ||||
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Competition of interest: none.
Additional material for this article may be found online at www.jvascsurg.org.
The editors and reviewers of this article have no relevant financial relationships to disclose per the JVS policy that requires reviewers to decline review of any manuscript for which they may have a competition of interest.
PII: S0741-5214(09)02095-3
doi:10.1016/j.jvs.2009.10.045
Published by Elsevier Inc.
