The need for treatment of hemodynamic instability following carotid endarterectomy is associated with increased perioperative and 1-year morbidity and mortality

OBJECTIVE

The objective of this study was to evaluate the outcomes of patients after carotid endarterectomy (CEA) who developed postoperative hypertension or hypotension requiring the administration of intravenous vasoactive medication (IVMED).

METHODS

We examined consecutive, primary elective CEA performed by 128 surgeons within the Vascular Study Group of New England (VSGNE) database (2003-2010) and compared outcomes of patients who required postoperative IVMED to treat hyper- or hypotension with those who did not. Outcomes included perioperative death, stroke, myocardial infarction (MI), congestive heart failure (CHF), hospital length of stay, and 1-year stroke or death. Propensity score matching was performed to facilitate risk-adjusted comparisons. Multivariable regression models were used to compare the association between IVMED and outcomes in unmatched and matched samples. Factors associated with use of IVMED in postoperative hypertension and hypotension were evaluated, and predictive performance of multivariable models was examined using receiver operating characteristic (ROC) curves.

RESULTS

Of 7677 elective CEAs identified, 23% received IVMED for treatment of either postoperative hypertension (11%) or hypotension (12%). Preoperative neurological symptomatic status (20%) was similar across cohorts. In the crude sample, the use of IVMED to treat postoperative hypertension was associated with increased 30-day mortality (0.7% vs 0.1%; P < .001), stroke (1.9% vs 1%; P = .018), MI (2.4% vs 0.5%; P < .001), and CHF (1.9% vs 0.5%; P < .001). The use of IVMED to treat postoperative hypotension was also associated with increased perioperative mortality (0.8% vs 0.1%; P < .001), stroke (3.2% vs 1.0%; P < .001), MI (2.7% vs 0.5%; P < .001), and CHF (1.7% vs 0.5%; P < .001), as well as 1-year death (5.1% vs 2.9%; P < .001) or stroke (4.2% vs 2.1%; P < .001). Hospital length of stay was significantly longer among patients who needed IVMED for postoperative hypertension (2.8 ± 4.7 days vs 1.7 ± 5.5 days; P < .001) and hypotension (2.8 ± 5.9 days vs 1.7 ± 5.5 days; P < .001). In multivariable analysis, IVMED for postoperative hypertension was associated with increased MI, stroke, or death (odds ratio, 2.6; 95% confidence interval [CI], 1.6-4.1; P < .001). Similarly, IVMED for postoperative hypotension was associated with increased MI, stroke, or death (odds ratio, 3.2; 95% CI, 2.1-5.0; P < .001), as well as increased 1-year stroke or death (hazard ratio, 1.6; 95% CI, 1.2-2.2; P = .003). Smoking, coronary artery disease, and clopidogrel (ROC, 0.59) were associated with postoperative hypertension requiring IVMED, whereas conventional endarterectomy and general anesthesia were associated with postoperative hypotension requiring IVMED (ROC, 0.58). The unitization of IVMED varied between 11% and 38% across VSGNE, and center effect did not affect outcomes.

CONCLUSIONS

Postoperative hypertension requiring IVMED after CEA is associated with increased perioperative mortality, stroke, and cardiac complications, whereas significant postoperative hypotension is associated with increased perioperative mortality, cardiac, or stroke complications, as well as increased 1-year death or stroke following CEA. The utilization of IVMED varied across centers and, as such, further investigation into this practice needs to occur in order to improve outcomes of these at-risk patients.

Regional intensity of vascular care and lower extremity amputation rates

OBJECTIVE

Because patient-level differences do not fully explain the variation in lower extremity amputation rates across the United States, we hypothesized that variation in intensity of vascular care may also affect regional rates of amputation and examined the relationship between the intensity of vascular care and the population-based rate of major lower extremity amputation (above-knee or below-knee) from vascular disease.

METHODS

Intensity of vascular care was defined as the proportion of Medicare patients who underwent any vascular procedure in the year before amputation, calculated at the regional level (2003 to 2006), using the 306 hospital referral regions in the Dartmouth Atlas of Healthcare. The relationship between intensity of vascular care and major amputation rate, at the regional level, was examined between 2007 and 2009.

RESULTS

Amputation rates varied widely by region, from one to 27 per 10,000 Medicare patients. Compared with regions in the lowest quintile of amputation rate, patients in the highest quintile were commonly African American (50% vs 13%) and diabetic (38% vs 31%). Intensity of vascular care also varied across regions: <35% of patients underwent revascularization in the lowest quintile of intensity, whereas nearly 60% underwent revascularization in the highest quintile. Overall, an inverse correlation was found between intensity of vascular care and the amputation rate, ranging from R = -0.36 for outpatient diagnostic and therapeutic procedures to R = -0.87 for inpatient surgical revascularizations. Analyses adjusting for patient characteristics and socioeconomic status found patients in high-intensity vascular care regions were significantly less likely to undergo amputation without an antecedent attempt at revascularization (odds ratio, 0.37; 95% confidence interval, 0.34-0.37; P < .001).

CONCLUSIONS

The intensity of vascular care provided to patients at risk for amputation varies, and regions with the most intensive vascular care have the lowest amputation rate, although the observational nature of these associations do not impart causality. High-risk patients, especially African American diabetic patients residing in low-intensity vascular care regions, represent an important target for systematic efforts to reduce amputation risk.

The effect of postoperative stroke and myocardial infarction on long-term survival after carotid revascularization

INTRODUCTION

The largest randomized controlled trial that compared the efficacy of carotid endarterectomy (CEA) with carotid artery stenting (CAS) showed equivalent outcomes for the composite end point of postoperative stroke, myocardial infarction (MI), or death. However, CAS had a higher risk of postoperative stroke, and CEA had a higher risk of MI. We hypothesize that there is a differential association of postoperative stroke, compared with that of postoperative MI, with reduced long-term survival after carotid revascularization when compared with neither complication.

METHODS

The Vascular Study Group of New England database was used to identify all CEA and CAS procedures performed between 2003 and 2011. Patients were stratified according to whether they experienced an in-hospital postoperative stroke (minor or major), MI (troponin elevation, electrocardiographic changes, or clinical symptoms), or neither. Primary study end point was survival during the first year and the first 5 years postoperatively. Multivariable Cox proportional hazards models compared the magnitude of association of stroke and MI on survival.

RESULTS

Of 8315 patients, 81 (0.97%) experienced postoperative MI, and 63 (0.76%) experienced stroke. During the first year after operation, survival significantly differed among the three groups: neither, 96%; MI, 84%; stroke, 77% (log-rank P < .0001). After adjusting for confounders, survival after postoperative stroke (hazard ratio [HR], 6.6; 95% confidence interval [CI], 3.7-12; P < .0001) was nearly twofold less than that after postoperative MI (HR, 3.6; 95% CI, 2-6.8; P < .0001). During the first 5 years postoperatively, multivariable modeling showed postoperative stroke and postoperative MI remained independent predictors of decreased survival, but the magnitude of association was similar (HR, 2.7; 95% CI, 1.7-4.3 [P < .0001] vs HR, 2.8; 95% CI, 1.8-4.3 [P < .0001]).

CONCLUSIONS

During the first year after operation, postoperative stroke conferred a twofold lower survival than that after postoperative MI. By 5 years after operation, these survival curves converged, and the survival disadvantage associated with stroke became similar to that of MI. These data suggest that different postoperative complications after carotid revascularization have different implications for patients, with decreased short-term survival in patients experiencing a postoperative stroke. These findings help to inform our interpretation of studies that have used a composite end point in order to evaluate the comparative effectiveness of revascularization strategies.

Outcomes of lower extremity bypass performed for acute limb ischemia

OBJECTIVE

Acute limb ischemia remains one of the most challenging emergencies in vascular surgery. Historically, outcomes following interventions for acute limb ischemia have been associated with high rates of morbidity and mortality. The purpose of this study was to determine contemporary outcomes following lower extremity bypass performed for acute limb ischemia.

METHODS

All patients undergoing infrainguinal lower extremity bypass between 2003 and 2011 within hospitals comprising the Vascular Study Group of New England were identified. Patients were stratified according to whether or not the indication for lower extremity bypass was acute limb ischemia. Primary end points included bypass graft occlusion, major amputation, and mortality at 1 year postoperatively as determined by Kaplan-Meier life table analysis. Multivariable Cox proportional hazards models were constructed to evaluate independent predictors of mortality and major amputation at 1 year.

RESULTS

Of 5712 lower extremity bypass procedures, 323 (5.7%) were performed for acute limb ischemia. Patients undergoing lower extremity bypass for acute limb ischemia were similar in age (66 vs 67; P = .084) and sex (68% male vs 69% male; P = .617) compared with chronic ischemia patients, but were less likely to be on aspirin (63% vs 75%; P < .0001) or a statin (55% vs 68%; P < .0001). Patients with acute limb ischemia were more likely to be current smokers (49% vs 39%; P < .0001), to have had a prior ipsilateral bypass (33% vs 24%; P = .004) or a prior ipsilateral percutaneous intervention (41% vs 29%; P = .001). Bypasses performed for acute limb ischemia were longer in duration (270 vs 244 minutes; P = .007), had greater blood loss (363 vs 272 mL; P < .0001), and more commonly utilized prosthetic conduits (41% vs 33%; P = .003). Acute limb ischemia patients experienced increased in-hospital major adverse events (20% vs 12%; P < .0001) including myocardial infarction, congestive heart failure exacerbation, deterioration in renal function, and respiratory complications. Patients who underwent lower extremity bypass for acute limb ischemia had no difference in rates of graft occlusion (18.1% vs 18.5%; P = .77), but did have significantly higher rates of limb loss (22.4% vs 9.7%; P < .0001) and mortality (20.9% vs 13.1%; P < .0001) at 1 year. On multivariable analysis, acute limb ischemia was an independent predictor of both major amputation (hazard ratio, 2.16; confidence interval, 1.38-3.40; P = .001) and mortality (hazard ratio, 1.41; confidence interval, 1.09-1.83; P = .009) at 1 year.

CONCLUSIONS

Patients who present with acute limb ischemia represent a less medically optimized subgroup within the population of patients undergoing lower extremity bypass. These patients may be expected to have more complex operations followed by increased rates of perioperative adverse events. Additionally, despite equivalent graft patency rates, patients undergoing lower extremity bypass for acute ischemia have significantly higher rates of major amputation and mortality at 1 year.

Abstract 323: Regional Variation in Patient Selection for Endovascular vs. Open Abdominal Aortic Aneurysm Repair

Objective: The purpose of this study was to analyze the factors that influence the choice of endovascular (EVAR) vs. open (OAAA) strategies for AAA repair, and examine how this decision varies between centers performing AAA repair in New England.

Methods: We examined prospectively collected data from 2,940 elective infrarenal AAA repairs (985 OAAAs and 1,955 EVARs) performed in 18 centers (2003-2011). All patients were anatomically acceptable candidates for either EVAR or OAAA. We identified pre-operative patient characteristics associated with treatment with EVAR (vs. OAAA repair), adjusting for year. The observed to expected ratio for EVAR utilization was compared across centers.

Results: Overall, EVAR utilization increased from 51% of all repairs in 2003 to 84% of all repairs in 2011 (p<0.001). EVAR utilization varied across centers, from 25 % of all repairs in one center , to 100% of all repairs in other centers (p<0.001). In multivariable analysis, factors associated with choosing EVAR for were increasing age over 65 (HR 1.6, p<0.01), male gender (HR 1.6, p<0.01), diabetes (HR 1.5, p=0.02), CAD (HR 1.5, p=0.01), CHF (HR 2.6, p<0.01), and COPD (HR 1.5, p<0.01). Even after adjustment for these factors, three centers performed EVAR at rates lower than expected (based on patient characteristics alone), and two centers performed EVAR at rates higher than expected ( p<0.05, Figure). In chi-pie analysis, 53 % of the observed variability in EVAR utilization was attributable to center variation and year of repair, while 47% was attributable to differences in patient characteristics.

Conclusion: Hospital practice patterns and adaption to technology influence the decision to perform EVAR more than patient characteristics, and many patients eligible for EVAR still undergo open repair in certain centers. Patients and providers interested in EVAR, irrespective of their anatomy, should seek out repair at centers most likely to perform these procedures.

Abstract 193: Primary Care Utilization Reduces Risk of Readmission among High-Risk Vascular Surgery Patients: Coordinating of Post-Discharge Care Matters

Objectives: Readmissions are a common and costly occurrence following high-risk surgical procedures, but may be avoided if problems are identified early in the post-discharge period. We hypothesized that routine follow-up with a primary care provider (PCP) might reduce 30-day readmissions following a high-risk vascular surgery procedure, thoracic aortic aneurysm (TAA) repair.

Methods: We conducted a retrospective cohort study of 42,935 Medicare beneficiaries who were discharged home from US hospitals following open TAA repair in 2003-2010. Primary care utilization was determined within 307 hospital referral regions described by the Dartmouth Atlas, as well as using a 20% sample of Medicare claims for outpatient primary care services within 30-days following TAA repair. We used hierarchical regression models, adjusted for patient and regional level differences, to examine the relationship between primary care utilization with 30-day readmission & mortality following TAA repair.

Results: 8,429 (20%) patients were readmitted within 30-days after open TAA repair, and more than 42% of readmissions occurred by 11 days post discharge. Among patients discharged following an uncomplicated hospital course, follow-up with a PCP within 30-days significantly reduced the risk of readmissions (Figure). Even after adjusting for differences in age, race, gender, and complications, PCP follow-up reduced the likelihood of 30-day readmission following TAA repair by over 30% (OR: 0.69; 95%CI: 0.49-0.97; P<0.05). As with most major surgical procedures, readmissions following TAA repair were more likely to occur among patients experiencing postoperative complications (21% vs. 19%, P<0.01). Finally, readmissions were less likely to occur in hospital referral regions with high primary care utilization as compared to regions with low rates of primary care utilization (19.4% high vs. 23.6% low; P<0.01).

Conclusions: Medicare recipients discharged following open TAA repair were significantly less likely to be readmitted in regions with high primary care utilization and when primary care follow-up occurred after surgery. These results highlight the need for better coordination of care between surgeons and primary care providers, and suggest an opportunity to focus quality improvement efforts to limit readmission.

Abstract 338: High Quality Medical Care: A Key Component in Access to Vascular Care for Patients with Lower Extremity PAD

Objectives: Prior work has demonstrated that patients at risk for amputation often have limited access to vascular care. We hypothesized that patients at risk for amputation may also have poor access to medical care related to their peripheral arterial disease (PAD). Therefore, we studied the intensity of medical care provided to patients at risk for amputation, and its relationship to access to vascular care.

Methods: We identified a cohort of 52,505 Medicare patients at risk for amputation (pre-existing diabetes, PAD, and foot ulceration) who required hospital admission for leg or foot cellulitis. Using the 307 hospital referral regions defined in the Dartmouth Atlas, we determined the proportion of patients that received appropriate, high quality medical care within 1 year (before or after) hospital admission. High-quality medical care was defined as evidence of (1) hemoglobin A1C testing (2) podiatric care, and (3) non-invasive vascular testing. Then, using regression analysis at the regional level, we assessed relationships between the use of high quality of medical care and access to diagnostic or therapeutic lower extremity vascular procedures.

Results: Across the United States, only 36% of diabetic patients with PAD and tissue loss received all three components of high quality medical care; 76% received 2 of 3 components. A non-invasive vascular study was absent in 41%. Provision of high-quality medical care varied across regions, from 4% of patients in Mason City, Iowa to 58% of patients in Sun City, Arizona. Regions that provided high quality medical care were significantly more likely to provide vascular care (R=0.30, p<0.001). Across quintiles of medical care quality, those regions most likely to provide high quality medical care were 24% more likely to provide invasive vascular care and revascularization (p<0.001, Figure).

Conclusions: Fewer than 4 out of 10 Medicare diabetics with PAD and tissue loss receive high-quality, appropriate medical care. Quality improvement efforts at limiting amputation need to incorporate multidisciplinary strategies and involve primary care providers, as high quality medical care is an important determinant of access to vascular care and limb preservation.

Blood transfusion for lower extremity bypass is associated with increased wound infection and graft thrombosis

BACKGROUND

Packed RBC transfusion has been postulated to increase morbidity and mortality after cardiac/general surgical operations, but its effects after lower extremity bypass (LEB) have not been studied extensively.

STUDY DESIGN

Using the Vascular Study Group of New England's database (2003-2010), we examined 1,880 consecutive infrainguinal LEB performed for critical limb ischemia. Perioperative transfusion was categorized as 0 U, 1 to 2 U, and ≥3 U. Cohort frequency group matching was used to compare groups of patients receiving 1 to 2 U and 0 U with patients receiving ≥3 U using age, coronary artery disease, diabetes, urgency, and indication of revascularization. Primary end points were perioperative mortality, wound infection, and loss of primary graft patency at discharge, as well as 1-year mortality and loss of primary graft patency.

RESULTS

In the study cohort, 1,532 LEBs (81.5%) received 0 U, 248 LEBs (13.2%) received 1 to 2 U, and 100 LEBs (5.3%) received ≥3 U transfusion. In the study cohort and group frequency matched cohort, transfusion was associated with significantly higher perioperative wound infection (0 U:4.8% vs 1 to 2 U: 6.5% vs ≥3 U: 14.0%; p = 0.0004) and graft thrombosis at discharge (4.5% vs 7.7% vs 15.3%; p < 0.0001). At 1 year, there were no differences in infection or graft patency. In multivariate analysis, transfusion was independently associated with increased perioperative wound infection in the study cohort and group frequency matched cohort (1 to 2 U vs 0 U: adjusted odds ratio [OR] = 1.4; 95% CI, 0.8-2.5; p = 0.263; ≥3 U vs 0 U: OR = 3.5; 95% CI, 1.8-6.7; p = 0.0002; overall p = 0.002) and increased graft thrombosis at discharge (1 to 2 U vs 0 U: OR = 2.1; 95% CI, 1.2-3.6; p = 0.01; ≥3 U vs 0 U: OR = 4.8; 95% CI, 2.5-9.2; p < 0.0001, overall p < 0.0001).

CONCLUSIONS

Perioperative transfusion in patients undergoing LEB is associated with increased perioperative wound infection and graft thrombosis. From this observational study, it appears transfusion does not have major consequences during mid-term follow-up, but the presumed benefits of blood replacement should be weighed carefully because of the increased risk of perioperative complications with transfusion.

Optimal selection of asymptomatic patients for carotid endarterectomy based on predicted 5-year survival

OBJECTIVE

Although carotid endarterectomy (CEA) is performed to prevent stroke, long-term survival is essential to ensure benefit, especially in asymptomatic patients. We examined factors associated with 5-year survival following CEA in patients with asymptomatic internal carotid artery (ICA) stenosis.

METHODS

Prospectively collected data from 4114 isolated CEAs performed for asymptomatic stenosis across 24 centers in the Vascular Study Group of New England between 2003 and 2011 were used for this analysis. Late survival was determined with the Social Security Death Index. Cox proportional hazard models were used to identify risk factors for mortality within the first 5 years after CEA and to calculate a risk score for predicting 5-year survival.

RESULTS

Overall 3- and 5-year survival after CEA in asymptomatic patients were 90% (95% CI 89%-91%) and 82% (95% CI 81%-84%), respectively. By multivariate analysis, increasing age, diabetes, smoking history, congestive heart failure, chronic obstructive pulmonary disease, poor renal function (estimated glomerular filtration rate <60 or dialysis dependence), absence of statin use, and worse contralateral ICA stenosis were all associated with worse survival. Patients classified as low (27%), medium (68%), and high risk (5%) based on number of risk factors had 5-year survival rates of 96%, 80%, and 51%, respectively (P < .001).

CONCLUSIONS

More than four out of five asymptomatic patients selected for CEA in the Vascular Study Group of New England achieved 5-year survival, demonstrating that, overall, surgeons in our region selected appropriate patients for carotid revascularization. However, there were patients selected for surgery with high risk profiles, and our models suggest that the highest risk patients (such as those with multiple major risk factors including age ≥ 80, insulin-dependent diabetes, dialysis dependence, and severe contralateral ICA stenosis) are unlikely to survive long enough to realize a benefit of prophylactic CEA for asymptomatic stenosis. Predicting survival is important for decision making in these patients.

Variation in smoking cessation after vascular operations

OBJECTIVE

Smoking is the most important modifiable risk factor for patients with vascular disease. The purpose of this study was to examine smoking cessation rates after vascular procedures and delineate factors predictive of postoperative smoking cessation.

METHODS

The Vascular Study Group of New England registry was used to analyze smoking status preoperatively and at 1 year after carotid endarterectomy, carotid artery stenting, lower extremity bypass, and open and endovascular abdominal aortic aneurysm repair between 2003 and 2009. Of 10,734 surviving patients after one of these procedures, 1755 (16%) were lost to follow-up and 1172 (11%) lacked documentation of their smoking status at follow-up. The remaining 7807 patients (73%) were available for analysis. Patient factors independently associated with smoking cessation were determined using multivariate analysis. The relative contribution of patient and procedure factors including treatment center were measured by χ-pie analysis. Variation between treatment centers was further evaluated by calculating expected rates of cessation and by analysis of means. Vascular Study Group of New England surgeons were surveyed regarding their smoking cessation techniques (85% response rate).

RESULTS

At the time of their procedure, 2606 of 7807 patients (33%) were self-reported current smokers. Of these, 1177 (45%) quit within the first year of surgery, with significant variation by procedure type (open abdominal aortic aneurysm repair, 50%; endovascular repair, 49%; lower extremity bypass, 46%; carotid endarterectomy, 43%; carotid artery stenting, 27%). In addition to higher smoking cessation rates with more invasive procedures, age >70 years (odds ratio [OR], 1.90; 95% confidence interval [CI], 1.30-2.76; P < .001) and dialysis dependence (OR, 2.38; 95% CI, 1.04-5.43; P = .04) were independently associated with smoking cessation, whereas hypertension (OR, 1.23; 95% CI, 1.00-1.51; P = .051) demonstrated a trend toward significance. Treatment center was the greatest contributor to smoking cessation, and there was broad variation in smoking cessation rates, from 28% to 62%, between treatment centers. Cessation rates were higher than expected in three centers and significantly lower than expected in two centers. Among survey respondents, 78% offered pharmacologic therapy or referral to a smoking cessation specialist, or both. The smoking cessation rate for patients of these surgeons was 48% compared with 33% in those who did not offer medications or referral (P < .001).

CONCLUSIONS

Patients frequently quit smoking after vascular surgery, and multiple patient-related and procedure-related factors contribute to cessation. However, we note significant influence of treatment center on cessation as well as broad variation in cessation rates between treatment centers. This variation indicates an opportunity for vascular surgeons to impact smoking cessation at the time of surgery.

Intraoperative use of dextran is associated with cardiac complications after carotid endarterectomy

OBJECTIVE

Although dextran has been theorized to diminish the risk of stroke associated with carotid endarterectomy (CEA), variation exists in its use. We evaluated outcomes of dextran use in patients undergoing CEA to clarify its utility.

METHODS

We studied all primary CEAs performed by 89 surgeons within the Vascular Study Group of New England database (2003-2010). Patients were stratified by intraoperative dextran use. Outcomes included perioperative death, stroke, myocardial infarction (MI), and congestive heart failure (CHF). Group and propensity score matching was performed for risk-adjusted comparisons, and multivariable logistic and gamma regressions were used to examine associations between dextran use and outcomes.

RESULTS

There were 6641 CEAs performed, with dextran used in 334 procedures (5%). Dextran-treated and untreated patients were similar in age (70 years) and symptomatic status (25%). Clinical differences between the cohorts were eliminated by statistical adjustment. In crude, group-matched, and propensity-matched analyses, the stroke/death rate was similar for the two cohorts (1.2%). Dextran-treated patients were more likely to suffer postoperative MI (crude: 2.4% vs 1.0%; P = .03; group-matched: 2.4% vs 0.6%; P = .01; propensity-matched: 2.4% vs 0.5%; P = .003) and CHF (2.1% vs 0.6%; P = .01; 2.1% vs 0.5%; P = .01; 2.1% vs 0.2%; P < .001). In multivariable analysis of the crude sample, dextran was associated with a higher risk of postoperative MI (odds ratio, 3.52; 95% confidence interval, 1.62-7.64) and CHF (odds ratio, 5.71; 95% confidence interval, 2.35-13.89).

CONCLUSIONS

Dextran use was not associated with lower perioperative stroke but was associated with higher rates of MI and CHF. Taken together, our findings suggest limited clinical utility for routine use of intraoperative dextran during CEA.

Using risk models to improve patient selection for high-risk vascular surgery

Vascular surgeons frequently perform procedures aimed at limiting death, stroke, or amputation on patients who present with diseases such as aortic aneurysms, carotid atherosclerosis, and peripheral arterial occlusive disease. However, now more than ever surgeons must balance the potential benefits associated with these interventions with the risks of physiologic insult for these elderly patients, who often have significant comorbidity burdens and the potential for costly complications. In this paper, we highlight how regional and national datasets can help surgeons identify which patients are most likely to benefit from vascular operations and which patients are most likely to suffer complications in the postoperative period. By using these guidelines to improve patient selection, our risk models can help patients, physicians, and policymakers improve the clinical effectiveness of surgical and endovascular treatments for vascular disease.

Derivation and validation of a practical risk score for prediction of mortality after open repair of ruptured abdominal aortic aneurysms in a US regional cohort and comparison to existing scoring systems

OBJECTIVE

Scoring systems for predicting mortality after repair of ruptured abdominal aortic aneurysms (RAAAs) have not been developed or tested in a United States population and may not be accurate in the endovascular era. Using prospectively collected data from the Vascular Study Group of New England (VSGNE), we developed a practical risk score for in-hospital mortality after open repair of RAAAs and compared its performance to that of the Glasgow aneurysm score, Hardman index, Vancouver score, and Edinburg ruptured aneurysm score.

METHODS

Univariate analysis followed by multivariable analysis of patient, prehospital, anatomic, and procedural characteristics identified significant predictors of in-hospital mortality. Integer points were derived from the odds ratio (OR) for mortality based on each independent predictor in order to generate a VSGNE RAAA risk score, which was internally validated using bootstrapping methodology. Discrimination and calibration of all models were assessed by calculating the area under the receiver-operating characteristic curve (C-statistic) and applying the Hosmer-Lemeshow test.

RESULTS

From 2003 to 2009, 242 patients underwent open repair of RAAAs at 10 centers. In-hospital mortality was 38% (n = 91). Independent predictors of mortality included age >76 years (OR, 5.3; 95% confidence interval [CI], 2.8-10.1), preoperative cardiac arrest (OR, 4.3; 95% CI, 1.6-12), loss of consciousness (OR, 2.6; 95% CI, 1.2-6), and suprarenal aortic clamp (OR, 2.4; 95% CI, 1.3-4.6). Patient stratification according to the VSGNE RAAA risk score (range, 0-6) accurately predicted mortality and identified those at low and high risk for death (8%, 25%, 37%, 60%, 80%, and 87% for scores of 0, 1, 2, 3, 4, and ≥5, respectively). Discrimination (C = .79) and calibration (χ(2) = 1.96; P = .85) were excellent in the derivation and bootstrap samples and superior to that of existing scoring systems. The Glasgow aneurysm score, Hardman index, Vancouver score, and Edinburg ruptured aneurysm score correlated with mortality in the VSGNE cohort but failed to identify accurately patients with a risk of mortality >65%.

CONCLUSIONS

Existing scoring systems predict mortality after RAAA repair in this cohort but do not identify patients at highest risk. This parsimonious VSGNE RAAA risk score based on four variables readily assessed at the time of presentation allows accurate prediction of in-hospital mortality after open repair of RAAAs, including identification of those patients at highest risk for postoperative mortality.