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Hawley H. Seiler Resident Award Paper

Have Thoracic Endografting Outcomes Improved Since US Food and Drug Administration Approval?

Division of Thoracic and Cardiovascular Surgery, Department of Surgery, University of Virginia School of Medicine, Charlottesville, Virginia

Accepted for publication January 12, 2011.

^_* Address correspondence to Dr Ailawadi, Division of Thoracic and Cardiovascular Surgery, University of Virginia Health System, P.O. Box 800679, Charlottesville, VA 22908 (Email: gorav{at}virginia.edu).

Presented at the Fifty-seventh Annual Meeting of the Southern Thoracic Surgical Association, Orlando, FL, Nov 3–6, 2010.

	Abstract

Top Abstract Introduction Material and Methods Results Comment Discussion Footnotes Acknowledgments References

 
Background: Thoracic endovascular aneurysm repair (TEVAR) is gaining acceptance since Food and Drug Administration approval in 2005. We hypothesize that, compared with open repair (OPEN), mortality and complication rate after TEVAR have continued to improve.

Methods: All patients who underwent thoracic and (or) thoracoabdominal aneurysm repair from 2005 to 2007 in the Nationwide Inpatient Sample were examined. Patients were stratified by TEVAR or OPEN. Demographics, hospital characteristics, and outcomes were analyzed. Multivariable logistic regression models for complications and in-hospital mortality were developed.

Results: A weighted total of 7,644 had TEVAR, while 32,948 patients underwent OPEN. The TEVAR utilization increased from 5.5% (2005) to 24.1% (2007). Mortality for all patients undergoing thoracic aneurysm repair decreased yearly (p <0.001). Mortality (TEVAR: 7.3%, OPEN: 9.8%, p <0.001) and complication rate (TEVAR: 24.3%, OPEN: 42.1%, p <0.001) were superior with TEVAR. The unadjusted annual mortality (7%) and complication rate (24%) after TEVAR did not improve each year; however, after risk adjustment, mortality after TEVAR steadily decreased annually. Moreover, risk-adjusted mortality for OPEN has improved since 2005. Multivariate analysis revealed age and ruptured aneurysm were highly predictive of death (p <0.001, respectively), while TEVAR lowered the adjusted odds of death by 18% (p <0.05).

Conclusions: Mortality in patients undergoing repair of thoracic aneurysms has decreased in the United States since Food and Drug Administration approval of stent grafts in 2005. This is due to wider adoption of TEVAR and improved mortality in patients undergoing TEVAR or open repair.

	Introduction

Top Abstract Introduction Material and Methods Results Comment Discussion Footnotes Acknowledgments References

 

The Hawley H. Seiler Resident Award is presented annually to the resident with the oral presentation and manuscript deemed the best of those submitted for the competition. This award was inaugurated in 1997 to honor Dr Seiler for his contributions and dedicated service to the Southern Thoracic Surgical Association.

 

The first endovascular repair of an infrarenal abdominal aortic aneurysm was reported by Parodi and colleagues in 1991 [1]. Soon thereafter, in 1992, the first endograft was developed and used to treat a descending thoracic aortic aneurysm (DTAA) [2]. In 2005, the United States Food and Drug Administration (FDA) approved the Gore TAG thoracic endoprosthesis (W. L. Gore & Associates, Inc, Flagstaff, AZ) [3]. Since then thoracic endovascular repair of aneurysms (TEVAR) has gained widespread adoption.

Open thoracic aneurysm repair is associated with significant morbidity resulting in poor long-term survival and prolonged hospitalization [4]. Compared with open repair, TEVAR portends shorter hospital stay, improved early recovery, and less perioperative morbidity and mortality. With more centers offering on-label and off-label TEVAR for complicated aortic diseases, endovascular repair is emerging as the preferred alternative to traditional open repair. Single institution results through the first two years using the Gore TAG device were favorable [5]. A recent report [6] demonstrated significantly better mortality rates and shorter length of stay after TEVAR compared with open thoracic aneurysm repair. Even as favorable midterm data become available [7–9], the effectiveness, national adoption, change in patient risk stratification, and trends of TEVAR remain unknown.

Previous volume-outcome relationships of cardiovascular operations [10–12] have shown that increasing experience is associated with improved clinical outcomes. Alternatively, we hypothesized that utilization of TEVAR has increased since FDA approval in 2005. Furthermore, we expect that mortality and complications have declined since 2005 with improving experience of thoracic endografting to treat aortic aneurysms.

	Material and Methods

Top Abstract Introduction Material and Methods Results Comment Discussion Footnotes Acknowledgments References

 
Data Source
Data were abstracted from the Nationwide Inpatient Sample (NIS) between 2005 and 2007. The NIS is the largest HCUP (Healthcare Cost and Utilization Project) all-payer inpatient database, sponsored by the AHRQ (Agency for Healthcare Research and Quality). The NIS contains data from more than 8 million hospital discharges annually from 1,056 hospitals located in 42 states, representing 90% of all US nonfederal hospital discharges (http://www.hcup-us.ahrq.gov/nisoverview.jsp) [13]. The AHRQ has developed appropriately scaled discharge weights to generate national estimates of hospitalizations from the NIS (http://www.hcup-us.ahrq.gov/db/nation/nis/nisdbdocumentation.jsp). These weights help compare hospitalization rates across years despite the varying number of states participating each year. The HCUP validates the NIS for biases by comparing it to other population-based datasets (http://www.hcup-us.ahrq.gov/reports/methods.jsp).

For this analysis, any missing cases more than 5% were excluded, imputations were not performed, while datasets were reviewed for any systematic missing values to be excluded from evaluation. Data reporting meets the NIS data-use agreement as established by HCUP. The NIS contains deidentified administrative level data and was not considered human subjects research, hence being exempted from review by the University of Virginia's Human Investigation Committee.

Patients
Patients were selected with a primary diagnosis of thoracic and (or) thoracoabdominal aneurysm with and (or) without rupture who underwent repair, identified using the International Statistical Classification of Diseases and Related Health Problems 9 Clinical Modification (ICD-9-CM) codes._^* The NIS database identifies up to 15 diagnoses and procedure codes, which were queried to identify and select patients at least 18 years of age. Only patients with ruptured and (or) nonruptured thoracic and (or) thoracoabdominal aneurysms who had undergone open surgical repair (OPEN) or thoracic endografting were included. Because cases are identified based on discharge level data, we included thoracoabdominal patients (6.7% of all aneurysm cases) in an attempt to comprehensively indentify all aneurysms of the thoracic aorta that underwent repair.

Patient risk factors were assessed using 30 different AHRQ comorbidities developed by Elixhauser and colleagues [14]. The Elixhauser comorbidities have been shown to provide effective adjustments for mortality risk among surgical populations [15], and have been shown to be superior to the Charlson-Deyo weighted score [16]. Aggregate comorbidities were stratified into up to 1, 2 to 4, and at least 5 comorbidity groups.

Outcomes of Interest
In-hospital mortality, complications, and discharge disposition after thoracic endografting were primary outcomes of interest. Complications were identified and limited to the hospital admission recorded ICD-9-CM codes. Routine discharge was considered discharge to home without services, while discharges against medical advice or to a skilled nursing facility were considered nonroutine. Because the NIS contains inpatient data only, complications occurring after hospital discharge cannot be evaluated. Several ICD-9-CM codes_^* were used to identify and aggregate complications into the following 8 categories: mechanical wound healing, postoperative infection, renal, pulmonary, gastrointestinal, cardiovascular, systemic, and procedure related [17].

Statistical Analysis
The strength of association between variables was measured using appropriate hypothesis tests. The significance of differences between proportions for categoric variables was evaluated by the Pearson ² test, while significant differences between mean values of continuous variables were assessed using single factor analysis of variance. Data are shown as number (n) with percentage by group (%), or mean with standard deviation (SD), except where indicated otherwise. As our sample size was large, we could discover certain differences to be statistically significant even if the practical relevances of these differences are clinically less applicable. Therefore, we computed three different effect sizes to provide practical and clinical value for comparisons. Cohen's d was calculated for continuous data by using pooled standard deviations, and was appropriately weighted for unequal sample size [18]. The phi () coefficient was computed for the ² tests for independence with 1 degree of freedom (df), while Cramer's V was computed for variables with more than 1 df [19]. We used the following thresholds to evaluate computed effect sizes: 0.32 or less (small), 0.33 to 0.55 (medium), and 0.56 or greater (large).

Yearly unadjusted odds for any complication and mortality in TEVAR and OPEN patients were calculated. Similarly, risk-adjusted models using covariates as described below were utilized to calculate odds ratios for any complication and mortality in these patients. Multivariable regression models for in-hospital mortality, any complication, and discharge disposition were developed to investigate the adjusted odds of death by controlling for differences in case-mix (demographics, preoperative characteristics) and procedure (hospital characteristics, year of procedure, repair type). The reference variables were selected based on clinical observation and included male gender, elective admission, OPEN surgery, large urban teaching hospital, and repair performed in 2007. Covariable selections for our models were made a priori based upon established volume associated outcomes literature. The models' predictive capacity to discriminate was measured using the area under the receiver operator characteristic curve. After excluding variables with missing values, more than 96% of the cases were included in the analysis, and had an area under the curve of at least 0.80. Adjusted odds ratios (AOR) are presented for each covariate along with their 95% confidence interval (CI). All data were analyzed using the Statistical Package for the Social Sciences 17 (SPSS Inc, Chicago, IL).

	Results

Top Abstract Introduction Material and Methods Results Comment Discussion Footnotes Acknowledgments References

 
Patient Demographics and Risk Factors
There were 7,644 (18.8%) TEVAR and 32,948 (81.2%) OPEN weighted cases that were reviewed (Fig 1 ). After approval of thoracic endografting in 2005, DTAA cases undergoing TEVAR increased rapidly (TEVAR cases: 2005, 5.5%; 2006, 24.9%; 2007, 24.1%). Patient demographics, risk factors, and hospital characteristics between TEVAR and OPEN were compared (Table 1). The TEVAR recipients were almost a decade older than OPEN patients. Female patients were more likely to undergo TEVAR (p < 0.001), while patients with at least 2 comorbidities, and those admitted over the weekend, were more likely to be TEVAR recipients (p < 0.001, respectively). A ruptured aneurysm was more than twofold likely to undergo treatment with TEVAR (p < 0.001).

View larger version (48K): [in this window] [in a new window]   Fig 1. Thoracic aneurysm repair trends over time. Distribution of thoracic endografting and open repair in aneurysm cases by year. The TEVAR and OPEN treated aneurysm cases are shown by year. (OPEN = open thoracic aneurysm repair; TEVAR = thoracic endovascular aneurysm repair.)

Unadjusted complication rate after TEVAR remained constant at 24% per year. Compared with 2007, there was no change in the annual risk of any complication in TEVAR after accounting for clinical influences (2005: AOR 1.21, 95% CI 0.97 to 1.52; 2006: AOR 1.10, 95% CI 0.96 to 1.26). Similarly in OPEN, referent to 2007, the annual unadjusted risk estimates were unchanged after other factors that impact complications were controlled (2005: AOR 0.99, 95% CI 0.93 to 1.05; 2006: AOR 0.98, 95% CI 0.92 to 1.05).

In-hospital Mortality After Aneurysm Repair
Although the unadjusted mortality after TEVAR did not change over time, the unadjusted mortality after OPEN improved (Table 4). Taken together, the difference in unadjusted mortality between these two procedures has narrowed over time (Fig 2 : 2005, 3.5%; 2006, 2.7%; 2007, 1.8%). Because patients undergoing TEVAR had more comorbidities over time, risk-adjusted mortality for TEVAR and open repair was evaluated. The adjusted risk estimates for mortality after TEVAR and OPEN have annually improved in a similar pattern.

View larger version (24K): [in this window] [in a new window]   Fig 2. Thoracic aneurysm mortality trend over time. In-hospital mortality trends of thoracic endografting and open repair over 3 years. Postoperative TEVAR and OPEN in-hospital mortality trends are shown by year. (OPEN = open thoracic aneurysm repair; TEVAR = thoracic endovascular aneurysm repair.)

	Comment

Top Abstract Introduction Material and Methods Results Comment Discussion Footnotes Acknowledgments References

 
This study presents the trends in the treatment of thoracic aortic aneurysms in a nationally representative database after FDA approval of thoracic stent grafts in 2005. As anticipated, the utilization of TEVAR has increased. During this period, unadjusted mortality and complication rates after TEVAR have not changed, while the case-complexity of patients undergoing TEVAR has increased. Importantly, the adjusted mortality after TEVAR has improved over time. Furthermore, the adjusted mortality for patients undergoing open aneurysm repair has also improved since 2005. The net result of these case-mix adjusted mortality data for both TEVAR and open surgery confirm that overall mortality in all patients undergoing DTAA repair in the US is improving after the availability of thoracic endografts.

Patients treated with TEVAR are different in many regards from those being treated with open repair. Specifically, TEVAR recipients were nearly 10 years older, had a larger number of comorbidities, and were more frequently nonelective. Despite this disparity, multivariate analysis in our study indicated that TEVAR was associated with improved mortality, a finding that is well supported by other series [4, 6, 7, 20–23]. A study published in 2005 comparing TEVAR and open repair showed that endovascular repair was associated with good early outcomes, lower mortality, and shorter hospital lengths of stay [24]. Since then, several studies have evaluated TEVAR in various populations. One small study [21] comprising 44 patients evaluated the effect of age on TEVAR and found no difference in 30-day mortality between octogenarians (mean age, 84 ± 2.7 years) and nonoctogenarians. In contrast, our study found that both in-hospital mortality and complications were influenced by increasing age. More recently, a study reviewing data over a 9-year period found that TEVAR had improved mortality, shorter hospitalization, and lower intensive care unit stay [25]. Similarly, in the current study hospital length of stay was shorter with TEVAR, as noted in other series.

In 2005, most centers performing TEVAR were still early in their learning curve with thoracic endografting procedures. Given the increase in use and wider application of TEVAR, it was anticipated that complication rates and in-hospital mortality would improve over time. However, the unadjusted complication rates did not improve as expected, likely due to "sicker" and more complex patients undergoing TEVAR each subsequent year. When these comorbidities were accounted for, the risk-adjusted complication rates still did not improve. The unadjusted mortality with TEVAR remained constant, when comorbidities were accounted for, the risk- adjusted mortality improved yearly. There are several potential explanations for these observations. First, it is possible that with FDA approval, experience with TEVAR is becoming more dilute such that more low volume centers are performing this procedure with liberalized inclusion criteria. Although TEVAR is less complex than open surgical repair, the subtleties of TEVAR cannot be overstated and greater individual center experience should decrease morbidity. Second, TEVAR is increasingly being performed in "sicker" patients with marginal anatomy. Although we are unable to comment on anatomic criteria, we speculate that less suitable patients with borderline anatomy for thoracic endograft, such as short necks-landing zones, angulated aortic arches, and heavily diseased iliofemoral vessels are being offered TEVAR. Thus as experience with TEVAR increases more complex patients are being treated with this approach, likely resulting in a greater unadjusted complication and mortality rate seen in our findings. A final potential explanation is that TEVAR has already reached the nadir of complication risk. However, this explanation is the least likely given that many centers are still learning this procedure. The annual improvement in adjusted mortality for TEVAR conceptually supports the fact that greater experience since FDA approval of stent grafts is directly influencing outcomes.

Aneurysm morphology and anatomic location within the thoracic aorta (arch or supraceliac) are expected to impact outcomes. Anecdotally, patients with less complex aortic aneurysm morphology during the early learning curve period were treated with stent grafting, and with improving confidence more patients with even complex disease were offered endografts. Significantly, early outcomes in the OPEN group might be slightly better a little earlier compared with later given that certain patients with intermediate or complex comorbidities were less likely to be treated by endografting early in our analysis. Conversely, later "sicker" patients were more likely to receive TEVAR with improving experience. These trends within groups might partially explain the OPEN results over time, and perhaps support the improvement in outcomes after TEVAR.

The improved unadjusted and adjusted mortality for open aneurysm repairs is interesting and has several potential explanations. First, with the availability of stent grafts, there appears to be a shift in the treatment of sicker patients including those with ruptured DTAA and those with higher premorbid risk toward TEVAR. This also suggests that surgeons are appropriately selecting patients for TEVAR and open surgical repair. Another potential explanation is that patients who require open thoracic aneurysm repair are increasingly being treated at high volume and (or) regional aortic centers. Finally, the techniques to minimize morbidity during open surgical repair including hybrid approaches, routine use of lumbar drains, and partial-left heart bypass may be becoming more prevalent, although they cannot be studied in this database.

As the experience with TEVAR grows and devices improve, the proportion of patients undergoing open repair is expected to decline. Patients who traditionally may not be considered candidates for TEVAR, including those patients with connective tissue disorders, appear to be increasing [26]. However, the utilization of TEVAR from 2006 to 2007 also remained constant, a finding that was not expected. This is most likely due to defined anatomic limitations of commercially available stent grafts. As newer generation devices evolve, these anatomic criteria will be broadened and the range of patients with descending thoracic aneurysms will increase. It should be noted that this study was designed to only evaluate thoracic aneurysm disease, the only FDA-approved indication for thoracic stent grafts. As such, patients with off-label use of TEVAR, including those with dissection, intramural hematoma, or blunt aortic injury, were not included. It is likely that the utilization of TEVAR is increasing with the inclusion of these off-label diagnoses.

There are several important considerations that are highlighted through this analysis. Paramount is the fact that our observational work provides empirical evidence for effective evaluation of outcomes between groups by randomized trial. As confounders and effect modifiers are expected to be homogenous and distributed across both groups, we anticipate that randomization would resolve the better treatment for thoracic aneurysm repair. Importantly, crossover patients would help identify risk factors and characteristics for improved patient selection and reducing treatment mismatch in the future. Another important aspect to remember is that patients included in this research may not have met all criteria of IFU (instructions for use). Although the current study assumes compliance with IFU among recipients, the reality is that with increasing surgeon-specific and center-specific experience, IFU standards were likely marginalized.

There are a number of other limitations to note in this study. In this retrospective analysis there is an inherent selection bias with limited data on the specific anatomy to assess the feasibility of TEVAR. The focus of this study was not to compare TEVAR with open surgery but rather to understand the utilization and morbidity trends over time after approval of endograft devices. Next, the NIS is a large database with the potential for erroneous miscoding among ICD-9-CM diagnostic and procedure codes. However, the NIS represents a random sampling of discharge level data that are externally and internally validated. Coding errors are expected to be homogenously distributed across all groups, thus equally effecting the groups in this evaluation. Importantly, as the NIS contains only discharge data, real perioperative mortality and morbidity may be unknown if it occurs after discharge from the index operation. Moreover, specific techniques to decrease the morbidity with these approaches including the use of cardiopulmonary bypass or cerebrospinal fluid drainage cannot be evaluated in our analysis. Finally, the potential for an unmeasured confounder may remain, which is inherent to the constraints of the NIS data points. We are unable to adjust for other well-established surgical risk factors such as low perioperative albumin levels or poor nutritional status.

Endovascular repair of thoracic aneurysms is gaining acceptance with increasing utilization over time after FDA approval in 2005. Thoracic endovascular aneurysm repair confers greater probability of discharge to home, lower complication rate, and decreased mortality. The complication rate after TEVAR has not improved but the risk adjusted in-hospital mortality is declining with increasing experience. In addition, the unadjusted and adjusted mortality of open surgical repair appears to be improving since the availability of TEVAR. These initial findings are promising and portend a significant shift in the treatment paradigm for thoracic aneurysmal disease.

	Discussion

Top Abstract Introduction Material and Methods Results Comment Discussion Footnotes Acknowledgments References

 
DR WILSON SZETO (Philadelphia, PA): Thank you for the opportunity here to lead this discussion. Good work, and congratulations to the authors from the University of Virginia for an outstanding paper; a large series, with complex statistical analysis. Several comments and just a few questions to keep it brief.

This is a large study of 32,000 patients undergoing open aortic repair, with just over 7,600 patients undergoing an endovascular approach. It is amazing that in just three years from '05 to '07 where our specialty has advanced. I think it is tremendous the innovative spirit that is still in this field today.

Based on your data, clearly these two groups of patients are different populations of patients, and, as you mentioned, because it is an administrative database, you were not able to get into the clinical aspects of it; ie, landing zones, anatomy, et cetera. But nonetheless, it is an administrative database of two very different populations: (1) patients undergoing open repair, and they include perhaps thoracoabdominal aneurysms, which, as you know, is a sicker population, and, (2) the endograft group, which is a group of patients with relatively straightforward descending aortic aneurysms. So, my first question pertains to your data demonstrating an improvement in the clinical outcome of the TEVAR [thoracic endovascular aneurysm repair] group over time, which is what you expect with a learning curve with this new technology. However, your data also demonstrated an improvement in the open group. What is your hypothesis as to why we are getting better in just the last three years with the open approach? Why do you think we are seeing that trend? Is it patient selection or are we truly getting better with the open technique in just two years? Did we really improve with our open surgical technique after 2005 with the introduction of the endograft technology?

The second question is based on this data. How has that affected your practice management at your center and what would you recommend to other centers in terms of patient selection? To whom should we offer TEVAR and open surgery? Which type of patients should we operate on with the open technique and who should we offer an endograft to?

Thanks again for the opportunity to lead the discussion.

DR BHAMIDIPATI: Thank you, Dr Szeto, for your kind comments. Indeed, this is an administrative database and therefore clinical metrics are not effectively captured. We knew this when we did the analysis, and we also realized that, overall, thoracoabdominal cases actually constituted only 6.7% of the total analysis, and, in one of the graphics that I showed, were actually more likely to be associated with TEVAR than open repair. One of the things that we wanted to make sure and do, was to capture all thoracic aneurysm surgery cases, and as we know with any administrative database, coding errors can exist; thus, without these cases we may not have effectively reflected all the patients that actually underwent surgery through this our analysis.

Now, to refer to your comment about before 2005 and whether we really knew what we were doing with open surgery. I think what we found out through this work is that the case complexity to treatment mismatch has actually gotten a lot better. So patient selection from a physician standpoint has significantly improved with time and will continue to evolve as experience continues to grow. Importantly, when we look at how we would recommend clinicians to practice after looking at this work, it is important to realize that in any early experience it is very important to stick with the criteria that were defined with the initial FDA [Food and Drug Administration] trial, and as with time experience grows, we will be able to draw on that experience to make better choices in patients. For example, one thing that we would like to have looked at is secondary complications and the need for reintervention, so you could predict which of these patients beforehand might require certain procedures and then have them undergo TEVAR surgery. So I think which patient should get TEVAR and which patient should get open repair is going to take a little bit more data and time to bear itself out as patient selection continues to improve. But overall, this early glimpse is promising for thoracic endografting. Thank you.

	Acknowledgments

Top Abstract Introduction Material and Methods Results Comment Discussion Footnotes Acknowledgments References

 
This study was supported by grant T32/ HL007849 from the National Heart, Lung, and Blood Institute to Castigliano M. Bhamidipati, DO, and Damien J. LaPar, MD. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Heart, Lung, and Blood Institute or the National Institutes of Health. This study was also supported by the Thoracic Surgery Foundation for Research and Education Research Grant to Gorav Ailawadi, MD.

	Footnotes

Top Abstract Introduction Material and Methods Results Comment Discussion Footnotes Acknowledgments References

 
^_* Recipient of the 2010 Hawley H. Seiler Resident Award.

^_* All ICD-9-CM codes can be made available to the reader upon receipt of an electronic request to the corresponding author (Gorav Ailawadi) at ga3f{at}virginia.edu.

	References

Top Abstract Introduction Material and Methods Results Comment Discussion Footnotes Acknowledgments References

 

1. Parodi JC, Palmaz JC, Barone HD. Transfemoral intraluminal graft implantation for abdominal aortic aneurysms Ann Vasc Surg 1991;5:491-499.[Medline]
2. Dake MD, Miller DC, Semba CP, Mitchell RS, Walker PJ, Liddell RP. Transluminal placement of endovascular stent-grafts for the treatment of descending thoracic aortic aneurysms N Engl J Med 1994;331:1729-1734.[Medline]
3. Makaroun MS, Dillavou ED, Kee ST, et al. Endovascular treatment of thoracic aortic aneurysms: results of the phase II multicenter trial of the GORE TAG thoracic endoprosthesis J Vasc Surg 2005;41:1-9.[Medline]
4. Leurs LJ, Bell R, Degrieck Y, Thomas S, et al. Endovascular treatment of thoracic aortic diseases: combined experience from the EUROSTAR and United Kingdom Thoracic Endograft registries J Vasc Surg 2004;40:670-680.[Medline]
5. Hughes GC, Daneshmand MA, Swaminathan M, et al. "Real world" thoracic endografting: results with the Gore TAG device 2 years after U.S. FDA approval Ann Thorac Surg 2008;86:1530-1538.[Abstract/Free Full Text]
6. Gopaldas RR, Huh J, Dao TK, et al. Superior nationwide outcomes of endovascular versus open repair for isolated descending thoracic aortic aneurysm in 11,669 patients J Thorac Cardiovasc Surg 2010;140:1001-1010.[Abstract/Free Full Text]
7. Go MR, Cho JS, Makaroun MS. Mid-term results of a multicenter study of thoracic endovascular aneurysm repair versus open repair Perspect Vasc Surg Endovasc Ther 2007;19:124-130.[Abstract/Free Full Text]
8. McPhee JT, Asham EH, Rohrer MJ, et al. The midterm results of stent graft treatment of thoracic aortic injuries J Surg Res 2007;138:181-188.[Medline]
9. Fernandez JD, Donovan S, Garrett Jr HE, Burgar S. Endovascular thoracic aortic aneurysm repair: evaluating the utility of intravascular ultrasound measurements J Endovasc Ther 2008;15:68-72.[Medline]
10. Hosenpud JD, Breen TJ, Edwards EB, Daily OP, Hunsicker LG. The effect of transplant center volume on cardiac transplant outcome. A report of the United Network for Organ Sharing Scientific Registry. JAMA 1994;271:1844-1849.[Medline]
11. Miyata H, Motomura N, Ueda Y, Matsuda H, Takamoto S. Effect of procedural volume on outcome of coronary artery bypass graft surgery in Japan: implication toward public reporting and minimal volume standards J Thorac Cardiovasc Surg 2008;135:1306-1312.[Abstract/Free Full Text]
12. Brooke BS, Perler BA, Dominici F, Makary MA, Pronovost PJ. Reduction of in-hospital mortality among California hospitals meeting Leapfrog evidence-based standards for abdominal aortic aneurysm repair J Vasc Surg 2008;47:1155-1156discussion 1163–1154.[Medline]
13. Nationwide Inpatient Sample. Healthcare cost utilization project. Rockville, MD: Agency for Healthcare Research and Quality; 2005–2008.
14. Elixhauser A, Steiner C, Harris DR, Coffey RM. Comorbidity measures for use with administrative data Med Care 1998;36:8-27.[Medline]
15. Stukenborg GJ, Wagner DP, Connors Jr AF. Comparison of the performance of two comorbidity measures, with and without information from prior hospitalizations Med Care 2001;39:727-739.[Medline]
16. Southern DA, Quan H, Ghali WA. Comparison of the Elixhauser and Charlson/Deyo methods of comorbidity measurement in administrative data Med Care 2004;42:355-360.[Medline]
17. Guller U, Hervey S, Purves H, et al. Laparoscopic versus open appendectomy: outcomes comparison based on a large administrative database Ann Surg 2004;239:43-52.[Medline]
18. Cohen J. Statistical power analysis for the behavioral sciences Hillsdale, NJ: Lawerence Erlbaum Associates 1988.
19. Lipsey WM. Design sensitivity: statistical power for experimental research Newbury Park, CA: Sage Publications, Inc 1990.
20. Ehrlich MP, Rousseau H, Heijman R, et al. Early outcome of endovascular treatment of acute traumatic aortic injuries: the talent thoracic retrospective registry Ann Thorac Surg 2009;88:1258-1263.[Abstract/Free Full Text]
21. Kpodonu J, Preventza O, Ramaiah VG, et al. Endovascular repair of the thoracic aorta in octogenarians Eur J Cardiothorac Surg 2008;34:630-634.[Abstract/Free Full Text]
22. Makaroun MS, Dillavou ED, Wheatley GH, Cambria RP, Gore TAG Investigators Five-year results of endovascular treatment with the Gore TAG device compared with open repair of thoracic aortic aneurysms J Vasc Surg 2008;47:912-918.[Medline]
23. Xenos ES, Minion DJ, Davenport DL, et al. Endovascular versus open repair for descending thoracic aortic rupture: institutional experience and meta-analysis Eur J Cardiothorac Surg 2009;35:282-286.[Abstract/Free Full Text]
24. Orandi BJ, Dimick JB, Deeb GM, Patel HJ, Upchurch Jr GR. A population-based analysis of endovascular versus open thoracic aortic aneurysm repair J Vasc Surg 2009;49:1112-1116.[Medline]
25. Arnaoutakis GJ, Hundt JA, Shah AS, Cameron DE, Black 3rd JH. Comparative analysis of hospital costs of open and endovascular thoracic aortic repair Vasc Endovascular Surg 2010;45:39-45.[Medline]
26. Svensson LG, Kouchoukos NT, Miller DC, et al. Expert consensus document on the treatment of descending thoracic aortic disease using endovascular stent-grafts Ann Thorac Surg 2008;85(1 Suppl):S1-S41.[Abstract/Free Full Text]

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