- Email: [email protected]
Open repair of intact thoracoabdominal aortic aneurysms in the American College of Surgeons National Surgical Quality Improvement Program
Open repair of intact thoracoabdominal aortic aneurysms in the American College of Surgeons National Surgical Quality Improvement Program Rodney P. Bensley, MD, Thomas Curran, MD, Rob Hurks, MD, PhD, Ruby C. Lo, MD, Mark C. Wyers, MD, Allen D. Hamdan, MD, Elliot L. Chaikof, MD, PhD, and Marc L. Schermerhorn, MD, Boston, Mass Objective: Open surgical repair of thoracoabdominal aortic aneurysms (TAAAs) is uncommon. Mortality rates of 20% are reported in studies using national data and are 5% to 8% in single-institution studies. Clinical trials are currently evaluating branched and fenestrated endografts. The purpose of this study is to establish a benchmark for future comparisons with endovascular trials using open repair of TAAAs in the National Surgical Quality Improvement Program (NSQIP) database. Methods: We identified all patients undergoing open elective and emergency surgical repair of intact TAAAs in NSQIP (2005 to 2010) using Current Procedural Terminology (American Medical Association, Chicago, Ill) and International Classification of Diseases, 9th Edition codes. We analyzed demographics, comorbidities, 30-day mortality, postoperative complications, and length of stay. Multivariable logistic regression was used to identify predictors of mortality. Results: We identified 450 patients who underwent open surgical repair (418 elective, 32 emergent) of an intact TAAA. Mean age was 69.4 years, 60.7% were male, and 85.6% were white. Comorbidities included hypertension (87.1%), chronic obstructive pulmonary disease (27.3%), prior stroke or transient ischemic attack (16.7%), diabetes (11.6%), and peripheral vascular disease (9.6%). Thirty-day mortality was 10.0%. Pulmonary complications were the most common: failure to wean from ventilator (39.1%), pneumonia (23.1%), and reintubation (13.8%). Acute renal failure requiring dialysis occurred in 10.7% of patients. Multivariable analysis (odds ratio [95% confidence interval]) showed predictors of mortality were emergent repair (3.3 [1.03-10.83]; P [ .04), age >70 years (3.5 [1.03-7.56], P [ .001), preoperative dialysis (8.4 [1.90-37.29], P [ .005), cardiac complication (2.9 [1.05-8.21], P [ .04), and renal complications (8.4 [3.41-20.56], P < .001). Conclusions: In this study of NSQIP hospitals, the first to analyze open surgical repair of TAAAs, the 30-day mortality rate of 10.0% is similar to single-institution reports. However, morbidity and mortality after open TAAA repair remain high, confirming the need for less invasive procedures. (J Vasc Surg 2013;58:894-900.)
Repair of thoracoabdominal aortic aneurysms (TAAAs) is uncommon and associated with high rates of postoperative morbidity and mortality. Studies using national data report mortality rates as high as 20% after open surgical repair,1,2 whereas large single-institution reviews report mortality rates as low as 5% to 8%.3-5 Although increasing surgeon and hospital volume have been associated with improved outcome,1 postoperative complications are common after open surgical repair at all centers and include From the Department of Surgery, Division of Vascular and Endovascular Surgery, Beth Israel Deaconess Medical Center and Harvard Medical School. This work was supported by the National Institutes of Health HarvardLongwood Research Training in Vascular Surgery Grant T32-HL007734. Author conflict of interest: Dr Schermerhorn is a consultant for Endologix and Medtronic. Dr Wyers is a consultant for Boston Scientific and Endologix. Dr Hamdan is a consultant for Endologix. Reprint requests: Marc L. Schermerhorn, MD, Department of Surgery, Beth Israel Deaconess Medical Center, 110 Francis St, Ste 5B, Boston, MA 02215 (e-mail: [email protected]). 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 conflict of interest. 0741-5214/$36.00 Copyright Ó 2013 by the Society for Vascular Surgery. http://dx.doi.org/10.1016/j.jvs.2013.03.037
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pulmonary, cardiac, and renal complications, as well as spinal cord ischemia and paraplegia. Owing to high rates of morbidity and mortality with open surgical repair, the hybrid technique, which combines open visceral artery debranching with endovascular aortic exclusion, has been used to treat TAAAs in patients who are unfit to withstand open repair. However, the role of the hybrid technique has yet to be defined, because studies reporting results of the hybrid technique are often reports from single institutions that are limited by their small sample size.6-8 The morbidity and mortality of open surgical repair of TAAAs have been previously reported using large singlecenter experiences and large administrative databases, such as the Nationwide Inpatient Sample (NIS). Previous NIS reports have provided an estimate of the real-world morbidity and mortality associated with TAAA repair outside of select centers of excellence, yet the NIS patient series has not been reported since 1998. This study is the first, to our knowledge, using a large national clinical database to examine outcomes after open surgical repair of TAAAs. The National Surgical Quality Improvement Program (NSQIP) clinical database is prospectively collected by trained clinical nurse reviewers who use standardized definitions of complications. Unlike the NIS, it does not rely
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on hospital coders or International Classification of Disease, 9th Edition (ICD-9) codes. Because morbidity and mortality remain high with open surgical repair, less invasive measures are needed, and clinical trials are currently evaluating branched and fenestrated endografts. Although like prior administrative reports, the NSQIP lacks specific anatomic data, we believe the NSQIP will provide a contemporary reappraisal as well as a more accurate measure of overall outcomes after open surgical repair of TAAAs that can be used to make comparisons with endovascular trials. METHODS This study was determined to be exempt from Review Board approval at the Beth Israel Deaconess Medical Center. Database. We analyzed data within the American College of Surgeons (ACS) NSQIP database from 2005 to 2010. Unlike administrative databases that are subject to the accuracy of hospital coders, the NSQIP prospectively collects risk-adjusted data from multiple institutions across the nation to facilitate quality-control review of outcomes. Since the conclusion of the pilot study in 2004, the program has grown to currently include 367 participating nonfederal community and academic medical centers across the United States. Although the NSQIP does not make hospital-level data available, the number of participating institutions more than doubled, from 121 to 258, during our study period (2005 to 2010). Depending on its overall volume, each center contributes all or a portion of operative cases performed, with selection occurring in a rotating manner to ensure a random representation of procedures and outcomes. Specially trained clinical nurse reviewers, who are initially trained and certified by the ACS and have ongoing training requirements, input the prospectively collected patient data at each participating institution using standardized definitions created by the ACS. The NSQIP data are subject to annual auditing, and the reliability of accurate data acquisition has improved with each passing year.9 A detailed list of demographic, comorbidity, and perioperative information is collected. Thirty-day postoperative outcomes, including information after hospitalization, are collected from hospital records, clinic visits, and followup phone contact. Hospitals participating in the ACS NSQIP have full access to the participant use file, which contains deidentified patient data from all participating sites. Patients. Clinical data were extracted from the NSQIP database using Current Procedural Terminology (American Medical Association, Chicago, Ill) procedure codes and ICD-9 diagnosis codes. We identified all patients with a primary diagnosis of an intact TAAA (ICD-9441.7) who underwent open surgical repair (CPT 33,877) from 2005 to 2010. Patients who are entered into the NSQIP database are given a primary diagnosis, which is obtained from the surgeon’s operative notes and is the indication for the
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operation. The principal operative procedure is listed along with 20 additional fields available for other operative procedures if they are performed under the same anesthetic. Subsequent procedures performed during the same hospitalization but under a different anesthetic are categorized by the generic variable “return to operating room within 30-days,” but the procedure is not specifically identified. Age, sex, race, and comorbid conditions were documented. Comorbid conditions, included diabetes mellitus (DM), chronic obstructive pulmonary disease (COPD), current smoking status, congestive heart failure, myocardial infarction (MI), prior percutaneous coronary intervention or coronary artery bypass grafting, hypertension, peripheral vascular disease, renal insufficiency (preoperative serum creatinine level >1.8 mg/dL; but not on dialysis), dialysis dependence, and cerebral vascular disease. Emergent or elective procedure status was also documented, with an emergent procedure defined by the notation of the operating surgeon and anesthesiologist and occurring #12 hours after hospital admission or after the onset of related preoperative symptoms. Outcomes. Our primary outcomes were 30-day mortality and postoperative complications. Pulmonary complications included failure to wean (total duration of ventilator-assisted respirations >48 hours), pneumonia, unplanned intubation (unplanned mechanical ventilation #30 days of surgery), and pulmonary embolism. Cardiac complications included MI (new transmural acute MI occurring during surgery or #30 days of surgery) and cardiac arrest (absence of cardiac rhythm or presence of chaotic rhythm, or both, that requires the initiation of basic or advanced cardiac life support #30 days of surgery). We also identified renal failure (requirement for hemodialysis, peritoneal dialysis, or ultrafiltration #30 days of surgery) and stroke (an embolic, thrombotic, or hemorrhagic vascular accident or stroke with motor, sensory, or cognitive dysfunction #30 days of the operation that persists for $24 hours). Also analyzed were total operative time, intraoperative red blood cell (RBC) transfusion requirement, and patient length of stay. Statistical analysis. SAS 9.3 statistical software (SAS Institute, Cary, NC) was used for statistical analyses. Categoric variables were analyzed using the c2 or Fisher exact test where appropriate. Continuous variables were compared using the Wilcoxon rank-sum test or two-tailed independent samples t-test, as appropriate. Data are reported for the study cohort as a whole. Comparisons were made between patients who survived their open TAAA repair and those who died. Bivariate predictors of 30-day mortality (P < .1) in Tables I and II, along with the intraoperative variables for procedure length and transfusion requirement, were evaluated by using multivariable logistic regression to determine independent predictors of death based on preoperative, intraoperative, and postoperative factors. Final multivariable models were determined using a stepwise backward elimination approach with covariates being eliminated for P > .05. Statistical significance was defined as P < .05.
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Table I. Demographics and comorbidities of the 450 patients who underwent open surgical repair of an intact thoracoabdominal aortic aneurysm (TAAA) in the National Surgical Quality Improvement Program (NSQIP) (2005 to 2010) and comparisons between those who died (n ¼ 45) and those who survived (n ¼ 405) Variablesa
All TAAA repairs (n ¼ 450)
Survived (n ¼ 405)
Died (n ¼ 45)
60.7 85.6 69.4 6 10.1
59.5 88.9 69.1 6 10.0
71.1 86.7 72.0 6 10.6
.15 .62 .07
26.8 6 5.5 11.6 27.3 43.8 1.6 0.7 18.9 26.2 87.1 9.6 10.7 2.4 16.7 7.1 1.1
26.8 6 5.5 11.9 27.2 43.7 1.7 0.7 18.5 25.7 87.2 8.9 9.9 1.7 16.3 6.2 0.7
26.7 6 5.4 8.9 28.9 44.4 0.0 0.0 22.2 31.1 86.7 15.6 17.8 8.9 20.0 15.6 4.4
.95 .81 .86 >.99 >.99 >.99 .55 .48 >.99 .18 .12 .02 .53 .03 .08
Demographics Male sex White race Age, years Clinical factors Body mass index, kg/m2 DM COPD Current smoker within 1 year Congestive heart failure MI Prior percutaneous coronary intervention Prior coronary artery bypass graft Hypertension Peripheral vascular disease Renal insufficiency (serum creatinine >1.8 mg/dL) Hemodialysis Cerebral vascular disease Emergent operation Preoperative transfusion >4 units
P
COPD, Chronic obstructive pulmonary disease; DM, diabetes mellitus; MI, myocardial infarction. a Continuous data are shown as the mean 6 standard deviation and categoric data as the percentage.
Table II. Thirty-day complications in all open thoracoabdominal aortic aneurysm repairs stratified by those who died from the repair compared with those who survived
Variable Any complication Pulmonary Failure to wean Pneumonia Reintubation Pulmonary embolism Cardiac MI Cardiac arrest Renal failure Stroke Return to operating room
Overall Died Survived (n ¼ 450), (n ¼ 45), (n ¼ 405), % % % 51.6 45.1 39.1 23.1 13.8 1.3 6.4 2.4 4.2 10.7 2.2 17.6
75.6 62.2 55.6 31.1 13.3 0.0 20.0 4.4 17.8 40.0 8.9 40.0
44.4 43.2 37.3 22.2 13.8 1.5 4.9 2.2 2.7 7.4 1.5 15.1
P <.001 .02 .02 .19 >.99 >.99 <.001 .30 <.001 <.001 .01 <.001
MI, Myocardial infarction.
RESULTS Patients. We identified 450 patients who underwent open surgical repair of an intact TAAA in NSQIP from 2005 to 2010. Patients were a mean age of 69.4 years, and most patients were white males (Table I). The most common comorbidities were hypertension (87.1%), COPD (27.3%), cerebral vascular disease (16.7%), DM (11.6%), and renal insufficiency with a serum creatinine >1.8 mg/dL (10.7%). Forty-four percent of patients were current
smokers within the past year. Seven percent of patients underwent an emergent repair of their intact TAAA. We used bivariate analysis to compare the 45 patients who died with the 405 patients who survived their open TAAA repair. The patients who died were nearly 3 years older than the surviving patients (72.0 vs 69.1 years, P ¼ .07) and more likely to be of male gender (71.1% vs 59.5%, P ¼ .15), but these were not significant. They were also more likely to be on preoperative dialysis (8.9% vs 1.7%, P ¼ .02) and to have undergone an emergent operation (15.6% vs 6.2%, P ¼ .03). Race and all other comorbidities were not significantly different. Intraoperative and 30-day postoperative outcomes. The mean operative time for all patients was 375 6 142 minutes; 369 6 136 minutes for patients surviving 30 days compared with 426 6 183 minutes for patients who died #30 days (P ¼ .05). Median length of stay for the entire cohort was 12 (range, 0-217 days); 7 days for those who died and 13 days for those who survived (P < .001). The overall mean intraoperative RBC transfusion requirement was 8.2 6 6.5 units. Patients who died had almost twice the intraoperative RBC transfusion requirement (13.8 6 9.7 vs 6.9 6 5.7 units; P < .001). The 30-day mortality rate for all patients was 10.0% (21.9% for emergent cases vs 9.1% for elective cases), and postoperative complications occurred in 51.6% (50.0% for emergent cases vs 51.7% for elective cases). Pulmonary complications were the most common, occurring in 45.1% of all patients: failure to wean in 39.1%, pneumonia in 23.1%, unplanned reintubation in 13.8%, and pulmonary embolism in 1.3%. Cardiac complications occurred in
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6.4% of all patients: MI in 2.4% and cardiac arrest in 4.2%. New-onset renal failure requiring dialysis occurred in 10.7% of all patients. Postoperative strokes were more common in emergent than in elective cases (12.5% vs 1.4%; P ¼ .003), although other system-specific complication rates did not differ according to procedure urgency. Table III lists the 30-day mortality and postoperative complication rates as they compare with a study that used the NIS1 and two large single-center experiences.3,4 Table II compares the complications that occurred between those who died and those who survived their open TAAA repair. Of those who died, 75.6% experienced at least one postoperative complication compared with 44.4% of those who survived (P < .001). Of the 11 who died without an NSQIP-defined complication, seven died on the day of surgery, and four died on the first postoperative day, suggesting that these deaths were likely intraoperative or directly related to intraoperative complications. Overall, pulmonary complications were higher in the patients who died (62.2% vs 43.2%; P ¼ .02), with failure to wean having the most significant difference (55.6% vs 37.3%; P ¼ .02). Pneumonia, reintubation, and pulmonary embolism were not significantly different between patients who died and those who survived. Overall, cardiac complications were higher in the patients who died (20.0% vs 4.9%; P < .001). Renal failure requiring dialysis (40.0% vs 7.4%; P < .001), stroke (8.9% vs 1.5%; P ¼ .01), and return to the operating room #30 days (40.0% vs 15.1%; P < .001) were all higher in the patients who died. Predictors of death. Multivariable analysis (odds ratio [OR] and 95% confidence interval [CI]) of patient demographics, comorbidities, and preoperative clinical factors identified age >70 years (2.8 [1.43-5.60]; P < .003), male gender (2.2 [1.05-4.39]; P ¼ .04), and preoperative dialysis (4.9 [1.11-22.12]; P ¼ .04) as independent preoperative predictors of 30-day mortality (Fig). Significance was maintained with the addition of the intraoperative variables of age >70 years, male gender, and preoperative dialysis. Also predictive were operative time >375 minutes (2.7 [1.37-5.23]; P ¼ .004) and emergent operation (2.9 [1.04-7.96]; P ¼ .04). The threshold for operative time was chosen by dichotomizing operative time to procedures longer or shorter than the mean value for the entire cohort. In a comprehensive model inclusive of postoperative complications, significance persisted for age >70 years, emergent operation, and preoperative dialysis, with renal complications (8.4 [3.41-20.56]; P < .001) and cardiac complications (2.9 [1.05-8.21]; P ¼ .04) also independent predictors of 30-day mortality. DISCUSSION With historically high morbidity and mortality rates, TAAA repair presents a substantial opportunity for improvement in outcome. The need for relevant benchmarks against which to conduct comparisons is critical. As such, we studied a primarily elective (93%) cohort of nonruptured open TAAA repairs in the NSQIP database from 2005 to 2010, with the main findings being an overall
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30-day mortality rate of 10.0% (emergent, 21.9%; elective, 9.1%; P ¼ .03) and a complication rate of 51.6% (emergent, 50.0%; elective, 51.7%; P ¼ .86). Pulmonary, renal, and cardiac complications were the most prevalent, with respective rates of 45.1%, 10.7%, and 6.4%. Independent preoperative and intraoperative predictors of 30-day mortality included age >70 years, male gender, emergent operation, preoperative hemodialysis, and operative time >375 minutes. Multivariable regression further emphasized the severe sequelae of postoperative complications, with cardiac and renal complications as independent predictors of death at 30 days. In this study of NSQIP hospitals, the first to analyze open surgical repair of intact TAAAs and their outcome, the 30-day mortality rate is less than half that of the 20.3% reported by Derrow et al2 and 22.3% reported by Cowan et al,1 both of whom analyzed open elective and emergent TAAA repair in the 1990s using the NIS, a discharge database representing a 20% random sample of United States hospital discharges. Yet, the 30-day mortality rate of 10.0% in the NSQIP is approaching, but not quite as low as the 5% to 8% mortality rate reported by large single-institution reviews spanning the 1960s through the 2000s.3-5 Cowan et al1 showed a significant improvement in the mortality rate with time, as the 30day mortality fell from 25.7% to 19.3% from the late 1980s to the mid-1990s. The same study also elucidated an inverse relationship between mortality rate and hospital volume, with a 30-day mortality rate of 15.0% for highvolume centers compared with 27.3% for low-volume centers. Preoperative predictors of perioperative mortality vary across studies, although increasing age, emergent operative admission, and preoperative renal insufficiency or hemodialysis were common to most analyses.1-3,5 The NSQIP data supported the previously demonstrated association of increasing age with 30-day mortality shown in the NIS data as well as the single-institution series presented by Svensson et al.1,5 Emergent operative admission, where studied, showed a trend toward significance3 or independent prediction of 30-day mortality, as was the case in our study.1 Although preoperative renal insufficiency was not an independent mortality predictor in our data, preoperative dialysis dependence was the strongest preoperative predictor of 30-day mortality. This is in line with other reports that show ORs of 1.2 to 3.1 for preoperative renal dysfunction where they did not distinguish between renal insufficiency and dialysis dependence.1,5 Other preoperative risk factors, such as gender, DM, coronary artery disease, transfusion requirement, and COPD, were not consistently predictive. A study of intraoperative risk factors yielded inconsistent results, with total aortic clamp time,5 intraoperative transfusion requirement, and intraoperative hypotension predictive only in individual studies.3 Accordingly, our study alone showed total operative time was an independent predictor for 30-day mortality. The overall complication rate of 51.6% in the NSQIP population was comparable to previously reported overall complication rates.1-4 System-specific complication rates
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Table III. Thirty-day postoperative outcomes after open thoracoabdominal aortic aneurysm repair in National Surgical Quality Improvement Program (NSQIP) from 2005 to 2010 compared with a study using the Nationwide Inpatient Sample (NIS) and two single-center experiences
Variable Mortality Overall complications Pulmonary Failure to wean Pneumonia Reintubation Pulmonary embolism Cardiac MI Cardiac arrest Renal failure Stroke Return to operating room
NSQIP (2005-2010) (n ¼ 450), %
NIS1 (1988-1998) (n ¼ 1542), %
Conrad et al3 (1987-2005) (n ¼ 455), %
Coselli et al4 (1986-2006) (n ¼ 2286), %
10.0 51.6 45.1 39.1 23.1 13.8 1.3 6.4 2.4 4.2 10.7 2.2 17.6
22.3 55.2 19.0 . . . . 14.8 . . 14.2 . .
8.4 . 49.0 . . . . 14.7 3.9 . 11.6 5.1 24.6
5.0 . 32.1 . . . . 7.9 . . 5.6 1.7 2.5
MI, Myocardial infarction.
Fig. Multivariable predictors of 30-day mortality: (A) preoperative, (B) preoperative and intraoperative, and (C) preoperative, intraoperative, and postoperative. All P values <.05. OR, Operation.
were also similar. Postoperative renal failure represented the strongest predictor of perioperative mortality, with an OR of 8.4 (95% CI, 3.41-20.56; P < .001), which paralleled the findings of Conrad et al3 who demonstrated an OR of 7.8 (95% CI, 3.4-17.9; P < .0001).3 Importantly, postoperative renal failure was the only postoperative complication to independently predict mortality in the NSQIP, NIS, and the two large, single-institution series.1 Cardiac complications in our study were noted with less frequency than previous experiences, with a rate of 6.4% compared with prior rates of 7.9% to 18.7%, which may be related to an absence of arrhythmia in our case definition.1-4 Cardiac complications were an independent predictor of mortality, as was the case in the NIS cohort and in the Baylor experience.1,5 Other complications, including gastrointestinal bleeding and stroke, were not consistently predictive. Interestingly, pulmonary complications, although not a predictor of mortality, showed protective ORs in the NSQIP cohort and in the Massachusetts General Hospital experience, which may be explained by a survivor bias. These gross system-specific complication
rates appear comparable, but a comparison between prior registry studies is a challenge given a lack of uniformity in system-specific complications. Our study offers the benefit of specific morbidities (ie, MI vs cardiac arrest) within these categories, which may permit more productive future comparisons. The improvement in mortality rate in the NSQIP cohort relative to previous large, national registry studies is likely multifactorial. A portion of this improvement can likely be attributed to the previously demonstrated temporal trend shown by Cowan et al,1 in which mortality fell by w20% during a 10-year period. This temporal trend may reflect improvements in general medical care, including statin use, blood pressure control, and identification of community-acquired pneumonia. Further contributions may have been made through improvements in critical care, operative technique, and patient selection. The last 2 decades have also seen significant progress in the areas of anesthesia, monitoring, and a multidisciplinary approach to critical care. From the surgical perspective, adjunctive techniques, such as spinal cord drainage and
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segmental clamping with distal aortic perfusion, have reduced not only the rates of paraplegia but also mortality. Further, hospital and surgeon volume relationships to mortality in TAAA repair1 and in other complex surgical procedures10,11 have been well delineated. Regionalization of select complex surgical procedures to high-volume centers has produced mortality benefits, and this too may contribute to outcome improvements in the NSQIP cohort.12 Despite these advancements, however, large studies, such as this, had not previously shown comparable open TAAA repair results to high-volume centers of excellence. Thus, with endovascular and hybrid techniques becoming increasingly common, it is important that we now have real-world estimates of open TAAA repair morbidity and mortality against which to measure progress.13 The findings reported here must be interpreted within the context of our study design and the design of the NSQIP database. Contributions to the NSQIP database are deidentified, so the hospital and surgeon are unknown; thus, other avenues must be used to further explore surgeon or hospital-volume relationships. In addition, the NSQIP database does not have certain procedure-specific data in its current iteration that are germane to the issues we have discussed here. Preoperatively, the database does not catalog anatomic information to assign Crawford classification or aneurysm diameter. Intraoperatively, techniques such as spinal drainage and distal aortic perfusion are not currently recorded nor are procedure-specific postoperative morbidities such as spinal cord injury. As such, the NSQIP cohort contains patients with an anatomically heterogeneous mixture of TAAAs undergoing open repair with a variety of adjunctive surgical procedures; yet, were these patients to undergo endovascular management of their aneurysms, they would require branched endografts or visceral/renal debranching plus endografting. Given this management consideration for patients with TAAAs, this series may serve as a benchmark for endovascular treatment of TAAAs with branched endografts or visceral/renal debranching plus endografting. As all prior reports on TAAA repair using national databases, including the NIS, have also included a heterogeneous mix of TAAA patients, this NSQIP cohort provides a contemporary reappraisal of all TAAA comers at a diverse group of institutions for a procedure that lacks robust data outside of singleinstitution centers of excellence. Finally, although the NSQIP dataset uses the strongest national data currently available for patients undergoing TAAA repair, there certainly remains a need for further large registry data with specific anatomic and intraoperative data. The Vascular Quality Initiative or the upcoming procedure-specific NSQIP may serve this purpose in the future, but until these data become available, the NSQIP cohort may serve as a reasonable benchmark. Regarding the timing of this report, new technologies, such as branched endografts, will soon be available that may introduce selection bias into any future comparison.
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We therefore felt it appropriate to document the current outcomes of TAAA repair before U.S. Food and Drug Administration approval of branched endografts. CONCLUSIONS In this study of NSQIP hospitals that perform open TAAA repair, the 30-day mortality rate of 10.0% is similar to those seen in large, single-institution reviews. Despite advances in critical care and intraoperative protective measures, morbidity and mortality after open TAAA repair remain high. Less invasive measures are needed to prevent the high rate of morbidity and mortality that accompanies open surgical repair. AUTHOR CONTRIBUTIONS Conception and design: RP, MS, MW, AH, EL Analysis and interpretation: RP, TC, RH, MS Data collection: RP, RH, RL Writing the article: RP, TC, MS Critical revision of the article: RP, TC, RL, MW, AH, EC, MS, RH Final approval of the article: RP, TC, RL, RH, MW, AH, EC, MS Statistical analysis: RP, TC Obtained funding: MS Overall responsibility: MS REFERENCES 1. Cowan JA Jr, Dimick JB, Henke PK, Huber TS, Stanley JC, Upchurch GR Jr. Surgical treatment of intact thoracoabdominal aortic aneurysms in the United States: hospital and surgeon volume-related outcomes. J Vasc Surg 2003;37:1169-74. 2. Derrow AE, Seeger JM, Dame DA, Carter RL, Ozaki CK, Flynn TC, et al. The outcome in the United States after thoracoabdominal aortic aneurysm repair, renal artery bypass, and mesenteric revascularization. J Vasc Surg 2001;34:54-61. 3. Conrad MF, Crawford RS, Davison JK, Cambria RP. Thoracoabdominal aneurysm repair: a 20-year perspective. Ann Thorac Surg 2007;83:S856-61; discussion: S890-2. 4. Coselli JS, Bozinovski J, LeMaire SA. Open surgical repair of 2286 thoracoabdominal aortic aneurysms. Ann Thorac Surg 2007;83: S862-4; discussion: S890-2. 5. Svensson LG, Crawford ES, Hess KR, Coselli JS, Safi HJ. Experience with 1509 patients undergoing thoracoabdominal aortic operations. J Vasc Surg 1993;17:357-68; discussion: 368-70. 6. Patel R, Conrad MF, Paruchuri V, Kwolek CJ, Chung TK, Cambria R. Thoracoabdominal aneurysm repair: hybrid versus open repair. J Vasc Surg 2009;50:15-22. 7. Ham SW, Chong T, Moos J, Rowe VL, Cohen RG, Cunningham MJ, et al. Arch and visceral/renal debranching combined with endovascular repair for thoracic and thoracoabdominal aortic aneurysms. J Vasc Surg 2011;54:30-40; discussion: 40-1. 8. Patel HJ, Upchurch GR Jr, Eliason JL, Criado E, Rectenwald J, Williams DM, et al. Hybrid debranching with endovascular repair for thoracoabdominal aneurysms: a comparison with open repair. Ann Thorac Surg 2010;89:1475-81. 9. Shiloach M, Frencher SK Jr, Steeger JE, Rowell KS, Bartzokis K, Tomeh MG, et al. Toward robust information: data quality and interrater reliability in the American College of Surgeons National Surgical Quality Improvement Program. J Am Coll Surg 2010;210:6-16. 10. Birkmeyer JD, Siewers AE, Finlayson EV, Stukel TA, Lucas FL, Batista I, et al. Hospital volume and surgical mortality in the United States. N Engl J Med 2002;346:1128-37.
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11. Birkmeyer JD, Stukel TA, Siewers AE, Goodney PP, Wennberg DE, Lucas FL. Surgeon volume and operative mortality in the United States. N Engl J Med 2003;349:2117-27. 12. Finks JF, Osborne NH, Birkmeyer JD. Trends in hospital volume and operative mortality for high-risk surgery. N Engl J Med 2011;364: 2128-37.
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13. Liao JM, Bakaeen FG, Cornwell LD, Simpson K, Lemaire SA, Coselli JS, et al. Nationwide trends and regional/hospital variations in open versus endovascular repair of thoracoabdominal aortic aneurysms. J Thorac Cardiovasc Surg 2012;144:612-6. Submitted Nov 12, 2012; accepted Mar 19, 2013.
Repair of thoracoabdominal aortic aneurysms (TAAAs) is uncommon and associated with high rates of postoperative morbidity and mortality. Studies using national data report mortality rates as high as 20% after open surgical repair,1,2 whereas large single-institution reviews report mortality rates as low as 5% to 8%.3-5 Although increasing surgeon and hospital volume have been associated with improved outcome,1 postoperative complications are common after open surgical repair at all centers and include From the Department of Surgery, Division of Vascular and Endovascular Surgery, Beth Israel Deaconess Medical Center and Harvard Medical School. This work was supported by the National Institutes of Health HarvardLongwood Research Training in Vascular Surgery Grant T32-HL007734. Author conflict of interest: Dr Schermerhorn is a consultant for Endologix and Medtronic. Dr Wyers is a consultant for Boston Scientific and Endologix. Dr Hamdan is a consultant for Endologix. Reprint requests: Marc L. Schermerhorn, MD, Department of Surgery, Beth Israel Deaconess Medical Center, 110 Francis St, Ste 5B, Boston, MA 02215 (e-mail: [email protected]). 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 conflict of interest. 0741-5214/$36.00 Copyright Ó 2013 by the Society for Vascular Surgery. http://dx.doi.org/10.1016/j.jvs.2013.03.037
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pulmonary, cardiac, and renal complications, as well as spinal cord ischemia and paraplegia. Owing to high rates of morbidity and mortality with open surgical repair, the hybrid technique, which combines open visceral artery debranching with endovascular aortic exclusion, has been used to treat TAAAs in patients who are unfit to withstand open repair. However, the role of the hybrid technique has yet to be defined, because studies reporting results of the hybrid technique are often reports from single institutions that are limited by their small sample size.6-8 The morbidity and mortality of open surgical repair of TAAAs have been previously reported using large singlecenter experiences and large administrative databases, such as the Nationwide Inpatient Sample (NIS). Previous NIS reports have provided an estimate of the real-world morbidity and mortality associated with TAAA repair outside of select centers of excellence, yet the NIS patient series has not been reported since 1998. This study is the first, to our knowledge, using a large national clinical database to examine outcomes after open surgical repair of TAAAs. The National Surgical Quality Improvement Program (NSQIP) clinical database is prospectively collected by trained clinical nurse reviewers who use standardized definitions of complications. Unlike the NIS, it does not rely
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on hospital coders or International Classification of Disease, 9th Edition (ICD-9) codes. Because morbidity and mortality remain high with open surgical repair, less invasive measures are needed, and clinical trials are currently evaluating branched and fenestrated endografts. Although like prior administrative reports, the NSQIP lacks specific anatomic data, we believe the NSQIP will provide a contemporary reappraisal as well as a more accurate measure of overall outcomes after open surgical repair of TAAAs that can be used to make comparisons with endovascular trials. METHODS This study was determined to be exempt from Review Board approval at the Beth Israel Deaconess Medical Center. Database. We analyzed data within the American College of Surgeons (ACS) NSQIP database from 2005 to 2010. Unlike administrative databases that are subject to the accuracy of hospital coders, the NSQIP prospectively collects risk-adjusted data from multiple institutions across the nation to facilitate quality-control review of outcomes. Since the conclusion of the pilot study in 2004, the program has grown to currently include 367 participating nonfederal community and academic medical centers across the United States. Although the NSQIP does not make hospital-level data available, the number of participating institutions more than doubled, from 121 to 258, during our study period (2005 to 2010). Depending on its overall volume, each center contributes all or a portion of operative cases performed, with selection occurring in a rotating manner to ensure a random representation of procedures and outcomes. Specially trained clinical nurse reviewers, who are initially trained and certified by the ACS and have ongoing training requirements, input the prospectively collected patient data at each participating institution using standardized definitions created by the ACS. The NSQIP data are subject to annual auditing, and the reliability of accurate data acquisition has improved with each passing year.9 A detailed list of demographic, comorbidity, and perioperative information is collected. Thirty-day postoperative outcomes, including information after hospitalization, are collected from hospital records, clinic visits, and followup phone contact. Hospitals participating in the ACS NSQIP have full access to the participant use file, which contains deidentified patient data from all participating sites. Patients. Clinical data were extracted from the NSQIP database using Current Procedural Terminology (American Medical Association, Chicago, Ill) procedure codes and ICD-9 diagnosis codes. We identified all patients with a primary diagnosis of an intact TAAA (ICD-9441.7) who underwent open surgical repair (CPT 33,877) from 2005 to 2010. Patients who are entered into the NSQIP database are given a primary diagnosis, which is obtained from the surgeon’s operative notes and is the indication for the
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operation. The principal operative procedure is listed along with 20 additional fields available for other operative procedures if they are performed under the same anesthetic. Subsequent procedures performed during the same hospitalization but under a different anesthetic are categorized by the generic variable “return to operating room within 30-days,” but the procedure is not specifically identified. Age, sex, race, and comorbid conditions were documented. Comorbid conditions, included diabetes mellitus (DM), chronic obstructive pulmonary disease (COPD), current smoking status, congestive heart failure, myocardial infarction (MI), prior percutaneous coronary intervention or coronary artery bypass grafting, hypertension, peripheral vascular disease, renal insufficiency (preoperative serum creatinine level >1.8 mg/dL; but not on dialysis), dialysis dependence, and cerebral vascular disease. Emergent or elective procedure status was also documented, with an emergent procedure defined by the notation of the operating surgeon and anesthesiologist and occurring #12 hours after hospital admission or after the onset of related preoperative symptoms. Outcomes. Our primary outcomes were 30-day mortality and postoperative complications. Pulmonary complications included failure to wean (total duration of ventilator-assisted respirations >48 hours), pneumonia, unplanned intubation (unplanned mechanical ventilation #30 days of surgery), and pulmonary embolism. Cardiac complications included MI (new transmural acute MI occurring during surgery or #30 days of surgery) and cardiac arrest (absence of cardiac rhythm or presence of chaotic rhythm, or both, that requires the initiation of basic or advanced cardiac life support #30 days of surgery). We also identified renal failure (requirement for hemodialysis, peritoneal dialysis, or ultrafiltration #30 days of surgery) and stroke (an embolic, thrombotic, or hemorrhagic vascular accident or stroke with motor, sensory, or cognitive dysfunction #30 days of the operation that persists for $24 hours). Also analyzed were total operative time, intraoperative red blood cell (RBC) transfusion requirement, and patient length of stay. Statistical analysis. SAS 9.3 statistical software (SAS Institute, Cary, NC) was used for statistical analyses. Categoric variables were analyzed using the c2 or Fisher exact test where appropriate. Continuous variables were compared using the Wilcoxon rank-sum test or two-tailed independent samples t-test, as appropriate. Data are reported for the study cohort as a whole. Comparisons were made between patients who survived their open TAAA repair and those who died. Bivariate predictors of 30-day mortality (P < .1) in Tables I and II, along with the intraoperative variables for procedure length and transfusion requirement, were evaluated by using multivariable logistic regression to determine independent predictors of death based on preoperative, intraoperative, and postoperative factors. Final multivariable models were determined using a stepwise backward elimination approach with covariates being eliminated for P > .05. Statistical significance was defined as P < .05.
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Table I. Demographics and comorbidities of the 450 patients who underwent open surgical repair of an intact thoracoabdominal aortic aneurysm (TAAA) in the National Surgical Quality Improvement Program (NSQIP) (2005 to 2010) and comparisons between those who died (n ¼ 45) and those who survived (n ¼ 405) Variablesa
All TAAA repairs (n ¼ 450)
Survived (n ¼ 405)
Died (n ¼ 45)
60.7 85.6 69.4 6 10.1
59.5 88.9 69.1 6 10.0
71.1 86.7 72.0 6 10.6
.15 .62 .07
26.8 6 5.5 11.6 27.3 43.8 1.6 0.7 18.9 26.2 87.1 9.6 10.7 2.4 16.7 7.1 1.1
26.8 6 5.5 11.9 27.2 43.7 1.7 0.7 18.5 25.7 87.2 8.9 9.9 1.7 16.3 6.2 0.7
26.7 6 5.4 8.9 28.9 44.4 0.0 0.0 22.2 31.1 86.7 15.6 17.8 8.9 20.0 15.6 4.4
.95 .81 .86 >.99 >.99 >.99 .55 .48 >.99 .18 .12 .02 .53 .03 .08
Demographics Male sex White race Age, years Clinical factors Body mass index, kg/m2 DM COPD Current smoker within 1 year Congestive heart failure MI Prior percutaneous coronary intervention Prior coronary artery bypass graft Hypertension Peripheral vascular disease Renal insufficiency (serum creatinine >1.8 mg/dL) Hemodialysis Cerebral vascular disease Emergent operation Preoperative transfusion >4 units
P
COPD, Chronic obstructive pulmonary disease; DM, diabetes mellitus; MI, myocardial infarction. a Continuous data are shown as the mean 6 standard deviation and categoric data as the percentage.
Table II. Thirty-day complications in all open thoracoabdominal aortic aneurysm repairs stratified by those who died from the repair compared with those who survived
Variable Any complication Pulmonary Failure to wean Pneumonia Reintubation Pulmonary embolism Cardiac MI Cardiac arrest Renal failure Stroke Return to operating room
Overall Died Survived (n ¼ 450), (n ¼ 45), (n ¼ 405), % % % 51.6 45.1 39.1 23.1 13.8 1.3 6.4 2.4 4.2 10.7 2.2 17.6
75.6 62.2 55.6 31.1 13.3 0.0 20.0 4.4 17.8 40.0 8.9 40.0
44.4 43.2 37.3 22.2 13.8 1.5 4.9 2.2 2.7 7.4 1.5 15.1
P <.001 .02 .02 .19 >.99 >.99 <.001 .30 <.001 <.001 .01 <.001
MI, Myocardial infarction.
RESULTS Patients. We identified 450 patients who underwent open surgical repair of an intact TAAA in NSQIP from 2005 to 2010. Patients were a mean age of 69.4 years, and most patients were white males (Table I). The most common comorbidities were hypertension (87.1%), COPD (27.3%), cerebral vascular disease (16.7%), DM (11.6%), and renal insufficiency with a serum creatinine >1.8 mg/dL (10.7%). Forty-four percent of patients were current
smokers within the past year. Seven percent of patients underwent an emergent repair of their intact TAAA. We used bivariate analysis to compare the 45 patients who died with the 405 patients who survived their open TAAA repair. The patients who died were nearly 3 years older than the surviving patients (72.0 vs 69.1 years, P ¼ .07) and more likely to be of male gender (71.1% vs 59.5%, P ¼ .15), but these were not significant. They were also more likely to be on preoperative dialysis (8.9% vs 1.7%, P ¼ .02) and to have undergone an emergent operation (15.6% vs 6.2%, P ¼ .03). Race and all other comorbidities were not significantly different. Intraoperative and 30-day postoperative outcomes. The mean operative time for all patients was 375 6 142 minutes; 369 6 136 minutes for patients surviving 30 days compared with 426 6 183 minutes for patients who died #30 days (P ¼ .05). Median length of stay for the entire cohort was 12 (range, 0-217 days); 7 days for those who died and 13 days for those who survived (P < .001). The overall mean intraoperative RBC transfusion requirement was 8.2 6 6.5 units. Patients who died had almost twice the intraoperative RBC transfusion requirement (13.8 6 9.7 vs 6.9 6 5.7 units; P < .001). The 30-day mortality rate for all patients was 10.0% (21.9% for emergent cases vs 9.1% for elective cases), and postoperative complications occurred in 51.6% (50.0% for emergent cases vs 51.7% for elective cases). Pulmonary complications were the most common, occurring in 45.1% of all patients: failure to wean in 39.1%, pneumonia in 23.1%, unplanned reintubation in 13.8%, and pulmonary embolism in 1.3%. Cardiac complications occurred in
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6.4% of all patients: MI in 2.4% and cardiac arrest in 4.2%. New-onset renal failure requiring dialysis occurred in 10.7% of all patients. Postoperative strokes were more common in emergent than in elective cases (12.5% vs 1.4%; P ¼ .003), although other system-specific complication rates did not differ according to procedure urgency. Table III lists the 30-day mortality and postoperative complication rates as they compare with a study that used the NIS1 and two large single-center experiences.3,4 Table II compares the complications that occurred between those who died and those who survived their open TAAA repair. Of those who died, 75.6% experienced at least one postoperative complication compared with 44.4% of those who survived (P < .001). Of the 11 who died without an NSQIP-defined complication, seven died on the day of surgery, and four died on the first postoperative day, suggesting that these deaths were likely intraoperative or directly related to intraoperative complications. Overall, pulmonary complications were higher in the patients who died (62.2% vs 43.2%; P ¼ .02), with failure to wean having the most significant difference (55.6% vs 37.3%; P ¼ .02). Pneumonia, reintubation, and pulmonary embolism were not significantly different between patients who died and those who survived. Overall, cardiac complications were higher in the patients who died (20.0% vs 4.9%; P < .001). Renal failure requiring dialysis (40.0% vs 7.4%; P < .001), stroke (8.9% vs 1.5%; P ¼ .01), and return to the operating room #30 days (40.0% vs 15.1%; P < .001) were all higher in the patients who died. Predictors of death. Multivariable analysis (odds ratio [OR] and 95% confidence interval [CI]) of patient demographics, comorbidities, and preoperative clinical factors identified age >70 years (2.8 [1.43-5.60]; P < .003), male gender (2.2 [1.05-4.39]; P ¼ .04), and preoperative dialysis (4.9 [1.11-22.12]; P ¼ .04) as independent preoperative predictors of 30-day mortality (Fig). Significance was maintained with the addition of the intraoperative variables of age >70 years, male gender, and preoperative dialysis. Also predictive were operative time >375 minutes (2.7 [1.37-5.23]; P ¼ .004) and emergent operation (2.9 [1.04-7.96]; P ¼ .04). The threshold for operative time was chosen by dichotomizing operative time to procedures longer or shorter than the mean value for the entire cohort. In a comprehensive model inclusive of postoperative complications, significance persisted for age >70 years, emergent operation, and preoperative dialysis, with renal complications (8.4 [3.41-20.56]; P < .001) and cardiac complications (2.9 [1.05-8.21]; P ¼ .04) also independent predictors of 30-day mortality. DISCUSSION With historically high morbidity and mortality rates, TAAA repair presents a substantial opportunity for improvement in outcome. The need for relevant benchmarks against which to conduct comparisons is critical. As such, we studied a primarily elective (93%) cohort of nonruptured open TAAA repairs in the NSQIP database from 2005 to 2010, with the main findings being an overall
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30-day mortality rate of 10.0% (emergent, 21.9%; elective, 9.1%; P ¼ .03) and a complication rate of 51.6% (emergent, 50.0%; elective, 51.7%; P ¼ .86). Pulmonary, renal, and cardiac complications were the most prevalent, with respective rates of 45.1%, 10.7%, and 6.4%. Independent preoperative and intraoperative predictors of 30-day mortality included age >70 years, male gender, emergent operation, preoperative hemodialysis, and operative time >375 minutes. Multivariable regression further emphasized the severe sequelae of postoperative complications, with cardiac and renal complications as independent predictors of death at 30 days. In this study of NSQIP hospitals, the first to analyze open surgical repair of intact TAAAs and their outcome, the 30-day mortality rate is less than half that of the 20.3% reported by Derrow et al2 and 22.3% reported by Cowan et al,1 both of whom analyzed open elective and emergent TAAA repair in the 1990s using the NIS, a discharge database representing a 20% random sample of United States hospital discharges. Yet, the 30-day mortality rate of 10.0% in the NSQIP is approaching, but not quite as low as the 5% to 8% mortality rate reported by large single-institution reviews spanning the 1960s through the 2000s.3-5 Cowan et al1 showed a significant improvement in the mortality rate with time, as the 30day mortality fell from 25.7% to 19.3% from the late 1980s to the mid-1990s. The same study also elucidated an inverse relationship between mortality rate and hospital volume, with a 30-day mortality rate of 15.0% for highvolume centers compared with 27.3% for low-volume centers. Preoperative predictors of perioperative mortality vary across studies, although increasing age, emergent operative admission, and preoperative renal insufficiency or hemodialysis were common to most analyses.1-3,5 The NSQIP data supported the previously demonstrated association of increasing age with 30-day mortality shown in the NIS data as well as the single-institution series presented by Svensson et al.1,5 Emergent operative admission, where studied, showed a trend toward significance3 or independent prediction of 30-day mortality, as was the case in our study.1 Although preoperative renal insufficiency was not an independent mortality predictor in our data, preoperative dialysis dependence was the strongest preoperative predictor of 30-day mortality. This is in line with other reports that show ORs of 1.2 to 3.1 for preoperative renal dysfunction where they did not distinguish between renal insufficiency and dialysis dependence.1,5 Other preoperative risk factors, such as gender, DM, coronary artery disease, transfusion requirement, and COPD, were not consistently predictive. A study of intraoperative risk factors yielded inconsistent results, with total aortic clamp time,5 intraoperative transfusion requirement, and intraoperative hypotension predictive only in individual studies.3 Accordingly, our study alone showed total operative time was an independent predictor for 30-day mortality. The overall complication rate of 51.6% in the NSQIP population was comparable to previously reported overall complication rates.1-4 System-specific complication rates
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Table III. Thirty-day postoperative outcomes after open thoracoabdominal aortic aneurysm repair in National Surgical Quality Improvement Program (NSQIP) from 2005 to 2010 compared with a study using the Nationwide Inpatient Sample (NIS) and two single-center experiences
Variable Mortality Overall complications Pulmonary Failure to wean Pneumonia Reintubation Pulmonary embolism Cardiac MI Cardiac arrest Renal failure Stroke Return to operating room
NSQIP (2005-2010) (n ¼ 450), %
NIS1 (1988-1998) (n ¼ 1542), %
Conrad et al3 (1987-2005) (n ¼ 455), %
Coselli et al4 (1986-2006) (n ¼ 2286), %
10.0 51.6 45.1 39.1 23.1 13.8 1.3 6.4 2.4 4.2 10.7 2.2 17.6
22.3 55.2 19.0 . . . . 14.8 . . 14.2 . .
8.4 . 49.0 . . . . 14.7 3.9 . 11.6 5.1 24.6
5.0 . 32.1 . . . . 7.9 . . 5.6 1.7 2.5
MI, Myocardial infarction.
Fig. Multivariable predictors of 30-day mortality: (A) preoperative, (B) preoperative and intraoperative, and (C) preoperative, intraoperative, and postoperative. All P values <.05. OR, Operation.
were also similar. Postoperative renal failure represented the strongest predictor of perioperative mortality, with an OR of 8.4 (95% CI, 3.41-20.56; P < .001), which paralleled the findings of Conrad et al3 who demonstrated an OR of 7.8 (95% CI, 3.4-17.9; P < .0001).3 Importantly, postoperative renal failure was the only postoperative complication to independently predict mortality in the NSQIP, NIS, and the two large, single-institution series.1 Cardiac complications in our study were noted with less frequency than previous experiences, with a rate of 6.4% compared with prior rates of 7.9% to 18.7%, which may be related to an absence of arrhythmia in our case definition.1-4 Cardiac complications were an independent predictor of mortality, as was the case in the NIS cohort and in the Baylor experience.1,5 Other complications, including gastrointestinal bleeding and stroke, were not consistently predictive. Interestingly, pulmonary complications, although not a predictor of mortality, showed protective ORs in the NSQIP cohort and in the Massachusetts General Hospital experience, which may be explained by a survivor bias. These gross system-specific complication
rates appear comparable, but a comparison between prior registry studies is a challenge given a lack of uniformity in system-specific complications. Our study offers the benefit of specific morbidities (ie, MI vs cardiac arrest) within these categories, which may permit more productive future comparisons. The improvement in mortality rate in the NSQIP cohort relative to previous large, national registry studies is likely multifactorial. A portion of this improvement can likely be attributed to the previously demonstrated temporal trend shown by Cowan et al,1 in which mortality fell by w20% during a 10-year period. This temporal trend may reflect improvements in general medical care, including statin use, blood pressure control, and identification of community-acquired pneumonia. Further contributions may have been made through improvements in critical care, operative technique, and patient selection. The last 2 decades have also seen significant progress in the areas of anesthesia, monitoring, and a multidisciplinary approach to critical care. From the surgical perspective, adjunctive techniques, such as spinal cord drainage and
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segmental clamping with distal aortic perfusion, have reduced not only the rates of paraplegia but also mortality. Further, hospital and surgeon volume relationships to mortality in TAAA repair1 and in other complex surgical procedures10,11 have been well delineated. Regionalization of select complex surgical procedures to high-volume centers has produced mortality benefits, and this too may contribute to outcome improvements in the NSQIP cohort.12 Despite these advancements, however, large studies, such as this, had not previously shown comparable open TAAA repair results to high-volume centers of excellence. Thus, with endovascular and hybrid techniques becoming increasingly common, it is important that we now have real-world estimates of open TAAA repair morbidity and mortality against which to measure progress.13 The findings reported here must be interpreted within the context of our study design and the design of the NSQIP database. Contributions to the NSQIP database are deidentified, so the hospital and surgeon are unknown; thus, other avenues must be used to further explore surgeon or hospital-volume relationships. In addition, the NSQIP database does not have certain procedure-specific data in its current iteration that are germane to the issues we have discussed here. Preoperatively, the database does not catalog anatomic information to assign Crawford classification or aneurysm diameter. Intraoperatively, techniques such as spinal drainage and distal aortic perfusion are not currently recorded nor are procedure-specific postoperative morbidities such as spinal cord injury. As such, the NSQIP cohort contains patients with an anatomically heterogeneous mixture of TAAAs undergoing open repair with a variety of adjunctive surgical procedures; yet, were these patients to undergo endovascular management of their aneurysms, they would require branched endografts or visceral/renal debranching plus endografting. Given this management consideration for patients with TAAAs, this series may serve as a benchmark for endovascular treatment of TAAAs with branched endografts or visceral/renal debranching plus endografting. As all prior reports on TAAA repair using national databases, including the NIS, have also included a heterogeneous mix of TAAA patients, this NSQIP cohort provides a contemporary reappraisal of all TAAA comers at a diverse group of institutions for a procedure that lacks robust data outside of singleinstitution centers of excellence. Finally, although the NSQIP dataset uses the strongest national data currently available for patients undergoing TAAA repair, there certainly remains a need for further large registry data with specific anatomic and intraoperative data. The Vascular Quality Initiative or the upcoming procedure-specific NSQIP may serve this purpose in the future, but until these data become available, the NSQIP cohort may serve as a reasonable benchmark. Regarding the timing of this report, new technologies, such as branched endografts, will soon be available that may introduce selection bias into any future comparison.
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We therefore felt it appropriate to document the current outcomes of TAAA repair before U.S. Food and Drug Administration approval of branched endografts. CONCLUSIONS In this study of NSQIP hospitals that perform open TAAA repair, the 30-day mortality rate of 10.0% is similar to those seen in large, single-institution reviews. Despite advances in critical care and intraoperative protective measures, morbidity and mortality after open TAAA repair remain high. Less invasive measures are needed to prevent the high rate of morbidity and mortality that accompanies open surgical repair. AUTHOR CONTRIBUTIONS Conception and design: RP, MS, MW, AH, EL Analysis and interpretation: RP, TC, RH, MS Data collection: RP, RH, RL Writing the article: RP, TC, MS Critical revision of the article: RP, TC, RL, MW, AH, EC, MS, RH Final approval of the article: RP, TC, RL, RH, MW, AH, EC, MS Statistical analysis: RP, TC Obtained funding: MS Overall responsibility: MS REFERENCES 1. Cowan JA Jr, Dimick JB, Henke PK, Huber TS, Stanley JC, Upchurch GR Jr. Surgical treatment of intact thoracoabdominal aortic aneurysms in the United States: hospital and surgeon volume-related outcomes. J Vasc Surg 2003;37:1169-74. 2. Derrow AE, Seeger JM, Dame DA, Carter RL, Ozaki CK, Flynn TC, et al. The outcome in the United States after thoracoabdominal aortic aneurysm repair, renal artery bypass, and mesenteric revascularization. J Vasc Surg 2001;34:54-61. 3. Conrad MF, Crawford RS, Davison JK, Cambria RP. Thoracoabdominal aneurysm repair: a 20-year perspective. Ann Thorac Surg 2007;83:S856-61; discussion: S890-2. 4. Coselli JS, Bozinovski J, LeMaire SA. Open surgical repair of 2286 thoracoabdominal aortic aneurysms. Ann Thorac Surg 2007;83: S862-4; discussion: S890-2. 5. Svensson LG, Crawford ES, Hess KR, Coselli JS, Safi HJ. Experience with 1509 patients undergoing thoracoabdominal aortic operations. J Vasc Surg 1993;17:357-68; discussion: 368-70. 6. Patel R, Conrad MF, Paruchuri V, Kwolek CJ, Chung TK, Cambria R. Thoracoabdominal aneurysm repair: hybrid versus open repair. J Vasc Surg 2009;50:15-22. 7. Ham SW, Chong T, Moos J, Rowe VL, Cohen RG, Cunningham MJ, et al. Arch and visceral/renal debranching combined with endovascular repair for thoracic and thoracoabdominal aortic aneurysms. J Vasc Surg 2011;54:30-40; discussion: 40-1. 8. Patel HJ, Upchurch GR Jr, Eliason JL, Criado E, Rectenwald J, Williams DM, et al. Hybrid debranching with endovascular repair for thoracoabdominal aneurysms: a comparison with open repair. Ann Thorac Surg 2010;89:1475-81. 9. Shiloach M, Frencher SK Jr, Steeger JE, Rowell KS, Bartzokis K, Tomeh MG, et al. Toward robust information: data quality and interrater reliability in the American College of Surgeons National Surgical Quality Improvement Program. J Am Coll Surg 2010;210:6-16. 10. Birkmeyer JD, Siewers AE, Finlayson EV, Stukel TA, Lucas FL, Batista I, et al. Hospital volume and surgical mortality in the United States. N Engl J Med 2002;346:1128-37.
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11. Birkmeyer JD, Stukel TA, Siewers AE, Goodney PP, Wennberg DE, Lucas FL. Surgeon volume and operative mortality in the United States. N Engl J Med 2003;349:2117-27. 12. Finks JF, Osborne NH, Birkmeyer JD. Trends in hospital volume and operative mortality for high-risk surgery. N Engl J Med 2011;364: 2128-37.
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13. Liao JM, Bakaeen FG, Cornwell LD, Simpson K, Lemaire SA, Coselli JS, et al. Nationwide trends and regional/hospital variations in open versus endovascular repair of thoracoabdominal aortic aneurysms. J Thorac Cardiovasc Surg 2012;144:612-6. Submitted Nov 12, 2012; accepted Mar 19, 2013.