Hospital costs for elective endovascular and surgical repairs of infrarenal abdominal aortic aneurysms

Duplex scanning as an alternative to computer tomography with contrast enhancement for the control of complications after endovascular aneurysm repair

EVAR (endovascular aneurism repair) is the preferred method for the surgical treatment of ananeurysm. The advantage of this type of surgical intervention is that a smaller number of postoperative complications will occur. The main diagnostic tasks for patients after EVAR are to determine the size of the aneurysmal sac, detection of an endoleak, detection of the endoprosthesis migration and the deformation of the stent graft itself. Conclusion: early detection of complications in the postoperative period remains the main problem for monitoring patients after EVAR. Duplex scanning is a safe, non-invasive and effective method of measuring the size of an aneurysmal sac and detecting possible complications after EVAR.

Endovascular versus “Fast-Track” Abdominal Aortic Aneurysm Repair

Recent studies have shown that endovascular abdominal aortic aneurysm repair (EVAR) has decreased costs, as well as decreased intensive care unit and total hospital length of stays when compared to abdominal aortic aneurysm (AAA) repair using a retroperitoneal exposure. The authors hypothesized that the fast-track AAA repair, which combines a retroperitoneal exposure with a patient care pathway that includes a gastric promotility agent and patient-controlled analgesia, would have no differences when compared to EVAR. Records of 58 patients who underwent AAA repair between April 14, 2000, and July 12, 2002, were reviewed retrospectively. Demographic information, length of stay, intraoperative and postoperative complications, mortality, and costs were evaluated. Fifty-eight AAA repairs were performed with the EVAR (n=28) and fast-track (n=30) techniques. The EVAR group was slightly older (72 vs 68 years, p=0.04), had slightly smaller average aneurysm size (5.5 ±0.13 vs 6.1 ±0.17 cm, p=0.008), and had more patients designated American Society of Anesthesia class 4 (p<0.0001). Both groups were predominantly male. Otherwise there were no statistically significant differences in risk factors. Patients who underwent fast-track repair tended to have a longer operation (216 ±7.4 vs 158 ±6.8 minutes, p<0.0001), with a greater volume of blood (1.8 ±0.29 vs 0.32 ±0.24 units, p=0.0005), colloid (565 ±89 vs 32 ±22 cc, p<0.0001), and crystalloid transfusions (4,625 ±252 vs 2,627 ±170 cc, p<0.0001). There were no statistically significant differences in the number of intraoperative or postoperative complications between the 2 groups. EVAR patients resumed a regular diet earlier (0.21 ±0.08 vs 1.8 ±0.11 days, p<0.0001). Intensive care unit stay was shorter for EVAR (0.50 ±0.10 vs 0.87 ±0.10 days, p=0.01), but floor (2.1 ±0.23 vs 2.6 ±0.21 days, p=0.17), and total hospital lengths of stay (2.8 ±0.32 vs 3.4 ±0.18 days, p=0.07) were similar between the 2 groups. Total hospital cost was lower in the fast-track ($10,205 ±$736 vs $20,640 ±$1,206, p<0.0001) leading to greater overall hospital earnings ($6,141 ±$1,280 vs $107 ±$1,940, p=0.01). Fast-track AAA repair is a viable alternative for the treatment of abdominal aortic aneurysms. Compared to endovascular repair, the fast-track method had increased transfusions of blood and intravenous fluids and increased operating room times, but equivalent lengths of floor and total hospital stay and increased total hospital earnings.

Reorganizing the System of Care Surrounding Laparoscopic Surgery: A Cost-Effectiveness Analysis Using Discrete-Event Simulation

Purpose. To determine the cost-effectiveness of a proposed reorganization of surgical and anesthesia care to balance patient volume and safety. Methods. Discrete-event simulation methods were used to compare current surgical practice with a newmodular system in which patient care is handed off between 2 anesthesiologists. Ahealth care system’s perspective, using hospital and professional costs, was chosen for the cost-effectiveness analysis. Outcomes were patient throughput, flow time, wait time, and resource use. Sensitivity analyses were performed on staffing levels, mortality rates, process times, and scheduled patient volume. Results. The new strategy was more effective (average 4.41 patients/d [median = 5] v. 4.29 [median = 4]) and had similar costs (average cost/ patient/d = $5327 v. $5289) to the current strategywith an incremental cost-effectiveness of $318/additional patient treated/d. Surgical mortality rate must be >4% or hand-off delay >15min before the new strategy is no longermore effective. Conclusion.The proposed system is more cost-effective relative to current practice over a wide range of mortality rates, hand-off times, and scheduled patient volumes.

A Multidimensional Analysis of Prostate Surgery Costs in the United States: Robotic-Assisted versus Retropubic Radical Prostatectomy

BACKGROUND

The economic value of robotic-assisted laparoscopic prostatectomy (RALP) in the United States is still not well understood because of limited view analyses.

OBJECTIVES

The objective of this study was to examine the costs and benefits of RALP versus retropubic radical prostatectomy from an expanded view, including hospital, payer, and societal perspectives.

METHODS

We performed a model-based cost comparison using clinical outcomes obtained from a systematic review of the published literature. Equipment costs were obtained from the manufacturer of the robotic system; other economic model parameters were obtained from government agencies, online resources, commercially available databases, an advisory expert panel, and the literature. Clinical point estimates and care pathways based on National Comprehensive Cancer Network guidelines were used to model costs out to 3 years. Hospital costs and costs incurred for the patients' postdischarge complications, adjuvant and salvage radiation treatment, incontinence and potency treatment, and lost wages during recovery were considered. Robotic system costs were modeled in two ways: as hospital overhead (hospital overhead calculation: RALP-H) and as a function of robotic case volume (robotic amortization calculation: RALP-R). All costs were adjusted to year 2014 US dollars.

RESULTS

Because of more favorable clinical outcomes over 3 years, RALP provided hospital ($1094 savings with RALP-H, $341 deficit with RALP-R), payer ($1451), and societal ($1202) economic benefits relative to retropubic radical prostatectomy.

CONCLUSIONS

Monte-Carlo probabilistic sensitivity analysis demonstrated a 38% to 99% probability that RALP provides cost savings (depending on the perspective). Higher surgical consumable costs are offset by a decreased hospital stay, lower complication rate, and faster return to work.

Duplex Ultrasound versus Computed Tomography for the Postoperative Follow-Up of Endovascular Abdominal Aortic Aneurysm Repair. Where Do We Stand Now?

In the last decade, endovascular aneurysm repair (EVAR) has rapidly developed to be the preferred method for infrarenal abdominal aortic aneurysm repair in patients with suitable anatomy. EVAR offers the advantage of lower perioperative mortality and morbidity but carries the cost of device-related complications such as endoleak, graft migration, graft thrombosis, and structural graft failure. These complications mandate a lifelong surveillance of EVAR patients and their endografts. The purpose of this study is to review and evaluate the safety of color-duplex ultrasound (CDU) as compared with computed tomography (CT), based on the current literature, for post-EVAR surveillance. The post-EVAR follow-up modalities, CDU versus CT, are evaluated questioning three parameters: (1) accuracy of aneurysm size, (2) detection and classification of endoleaks, and (3) detection of stent-graft deformation. Studies comparing CDU with CT scan for investigation of post-EVAR complications have produced mixed results. Further and long-term research is needed to evaluate the efficacy of CDU versus CT, before CDU can be recommended as the primary imaging modality for EVAR surveillance, in place of CT for stable aneurysms.

The financial implications of endovascular aneurysm repair in the cost containment era

OBJECTIVE

Endovascular aneurysm repair (EVAR) is associated with significant direct device costs. Such costs place EVAR at odds with efforts to constrain healthcare expenditures. This study examines the procedure-associated costs and operating margins associated with EVAR at a tertiary care academic medical center.

METHODS

All infrarenal EVARs performed from April 2011 to March 2012 were identified (n = 127). Among this cohort, 49 patients met standard commercial instruction for use guidelines, were treated using a single manufacturer device, and billed to Medicare diagnosis-related group (DRG) 238. Of these 49 patients, net technical operating margins (technical revenue minus technical cost) were calculated in conjunction with the hospital finance department. EVAR implant costs were determined for each procedure. DRG 238-associated costs and length of stay were benchmarked against other academic medical centers using University Health System Consortium 2012 data.

RESULTS

Among the studied EVAR cohort (age 75, 82% male, mean length of stay, 1.7 days), mean technical costs totaled $31,672. Graft implants accounted for 52% of the allocated technical costs. Institutional overhead was 17% ($5495) of total technical costs. Net mean total technical EVAR-associated operating margins were -$4015 per procedure. Our institutional costs and length of stay, when benchmarked against comparable centers, remained in the lowest quartile nationally using University Health System Consortium costs for DRG 238. Stent graft price did not correlate with total EVAR market share.

CONCLUSIONS

EVAR is currently associated with significant negative operating margins among Medicare beneficiaries. Currently, device costs account for over 50% of EVAR-associated technical costs and did not impact EVAR market share, reflecting an unawareness of cost differential among surgeons. These data indicate that EVAR must undergo dramatic care delivery redesign for this practice to remain sustainable.

Cost and effectiveness comparison of endovascular aneurysm repair versus open surgical repair of abdominal aortic aneurysm: a single-center experience

The study objective was to compare the cost and effectiveness of two surgical techniques: open repair and endovascular aneurysm repair (EVAR) of abdominal aortic aneurysm (AAA). We assessed 58 surgical operations of AAA repair conducted in 54 men and 4 women (aged 49-94 years) during 2003 and 2004. Open surgical repair was performed in 21 patients, and EVAR was performed in 37 patients. The evaluation of the effectiveness of both methods was based on the following factors: mortality within 30 days, surgery duration, total hospitalization time, and intensive care unit stay duration. The segmental costs of grafts, anesthesia, and extra materials were included in the calculations for the comparison of the costs of the two methods. A 30-day mortality of 5.17% and 0% was demonstrated for open surgical repair and EVAR, respectively. In regard to the operation's mean duration, this was calculated to 279.52 minutes for open repair and 193.57 minutes for EVAR. The mean duration of the in-hospital stay was 11.3 and 4.09 days for open repair and EVAR, respectively. Accordingly, the mean duration of intensive care unit stay was 2.81 and 0.23 days, respectively. The cost evaluation revealed a mean cost of 5374.3euro ($7,643.49) and 20,592.52euro ($29,287.50) for open repair and EVAR, respectively. Open repair is a "tested method" of its own time. EVAR seems to have the advantage on aspects of effectiveness, yet its major hallmark is its significant cost, as indicated in the relevant part of the current study.

Failure properties of intraluminal thrombus in abdominal aortic aneurysm under static and pulsating mechanical loads

OBJECTIVES

It has been suggested that mechanical failure of intraluminal thrombus (ILT) could play a key role in the rupture of abdominal aortic aneurysms (AAAs), and in the present study, this hypothesis has been investigated. An in vitro experimental approach has been proposed, which provides layer-specific failure data of ILT tissue under static and pulsatile mechanical loads.

METHODS

In total, 112 bone-shaped test specimens are prepared from luminal, medial, and abluminal layers of eight ILTs harvested during open elective AAA repair. Three different types of mechanical experiments, denoted as control test, ultimate strength test, and fatigue test were performed in Dulbecco's modified eagle's medium (DMEM) supplemented with fetal calf serum, L-ascorbic acid, and antibiotics at 37 degrees C and pH 7.0. In detail, fatigue tests, which are experiments, where the ILT tissue is loaded in pulsatile manner, were carried out at three different load levels with a natural frequency of 1.0 Hz.

RESULTS

ILT's ultimate strength (156.5 kPa, 92.0 kPa, and 47.7 kPa for luminal, medial, and abluminal layers, respectively) and referential stiffness (62.88 kPa, 47.52 kPa, and 41.52 kPa, for luminal, medial, and abluminal layers, respectively) continuously decrease from the inside to the outside. ILT tissue failed within less than 1 hour under pulsatile loading at a load level of 60% ultimate strength, while a load level of about 40% ultimate strength did not cause failure within 13.9 hours.

CONCLUSIONS

ILT tissue is vulnerable against fatigue failure and shows significant decreasing strength with respect to the number of load cycles. Hence, after a reasonable time of pulsating loading ILT's strength is far below its ultimate strength, and when compared with stress predictions from finite element (FE) studies, this indicates the likelihood of fatigue failure in vivo. Failure within the ILT could propagate towards the weakened vessel wall behind it and could initialize AAA failure thereafter.

Long-term postplacement cost after endovascular aneurysm repair

BACKGROUND

Previous studies have demonstrated that the initial hospital cost associated with endovascular aneurysm repair (EVAR) is approximately $20,000. However, the cost of long-term surveillance and secondary procedures is poorly characterized.

METHODS

Between December 1998 and June 2006, 259 patients underwent EVAR for infrarenal aneurysms at a single institution. Follow-up costs were calculated using a relative value unit based hospital cost accounting system, which incorporates departmental direct and indirect costs. Institutional overhead costs were included using a conversion factor. Costs for professional services were determined by a cost-to-charge ratio, and outpatient visits were calculated with a time-based formula. Year 2006 costs were applied to prior years. To minimize costs associated with the early learning curve, the initial 50 EVAR patients between December 1995 and 1998 were excluded. Patients with <1 year follow-up were also excluded. Data are expressed as mean +/- standard error.

RESULTS

The mean follow-up after EVAR for 136 patients was 34.7 +/- 1.8 months. The cumulative 5-year postplacement cost per patient was $11,351. The 27 patients (19.9%) who required secondary procedures had a 5-year cumulative cost of $31,696 compared with $3668 for 109 patients without secondary procedures (8.6-fold increase, P < .05). The 5-year cost for patients with endoleak was $26,739 compared with $5706 for those without endoleak (4.7-fold increase, P < .05). Overall, major cost components were 57.4% for secondary procedures and 32.5% for radiologic studies.

CONCLUSIONS

During a 5-year period, the postplacement cost of EVAR increases the global cost by 44%. The subgroups of patients with endoleaks and those requiring secondary procedures generate a disproportionate share of postplacement costs. Efforts at minimizing cost should emphasize technical and device modifications aimed at reducing endoleaks and the need for secondary procedures.

Cost-effectiveness of abdominal aortic aneurysm repair: A systematic review

Objectives: A systematic review of the cost-effectiveness of abdominal aortic aneurysm (AAA) repair was conducted. Although open surgery has been considered the gold standard for prevention of AAA rupture, emerging less-invasive endovascular treatments have led to increased interest in evaluating the cost and cost-effectiveness of treatment options.

Methods: A systematic review of studies published in MEDLINE between 1999 and 2005 reporting the cost and/or cost-effectiveness of endovascular and/or open surgical repair of nonruptured AAAs was conducted. Case series studies with less than fifty patients per treatment were excluded.

Results: Of twenty eligible articles, three were randomized controlled trials, twelve case series, four Markov models, and one systematic review. Regardless of time frame, all studies found that endovascular repair costs more than open surgery. Although the high cost of the endovascular prosthesis was partially offset by reduced intensive care, hospital length of stay, operating time, blood transfusions, and perioperative complications, hospital costs were still greater for endovascular than open surgical repair. For patients medically fit for open surgery, mid-term costs were greater for endovascular repair with no difference in overall survival or quality of life. For patients medically unfit for open surgery, endovascular repair costs more than no intervention with no difference in survival.

Conclusions: Although conclusions regarding the cost-effectiveness of AAA treatment options are time dependent and vary by institutional perspective, from a societal perspective, endovascular repair is not currently cost-effective for patients with large AAA regardless of medical fitness.

The effects of aneurysm on the biaxial mechanical behavior of human abdominal aorta

The biomechanical response of normal and pathologic human abdominal aortic tissue to uniaxial loading conditions is insufficient for the characterization of its three-dimensional (3D) mechanical behavior. Planar biaxial mechanical evaluation allows for 3D constitutive modeling of nearly incompressible tissues, as well as the investigation of the nature of mechanical anisotropy. In the current study, 26 abdominal aortic aneurysm (AAA) tissue samples and 8 age-matched (> 60 years of age) nonaneurysmal abdominal aortic (AA) tissue samples were obtained and tested using a tension-controlled biaxial testing protocol. Graphical response functions (Sun et al., 2003. J. Biomech. Eng. 125, 372-380) were used as a guide to describe the pseudo-elastic response of AA and AAA. Based on the observed pseudo-elastic response, a four-parameter exponential strain energy function developed by Vito (1990. J. Biomech. Eng. 112, 153-159) was used from which both an individual specimen and group material parameter sets were determined for both AA and AAA. Peak Green strain values in the circumferential (Ethetatheta,max) and longitudinal (ELL,max) directions under an equibiaxial tension of 120 N/m were also compared. The strain energy function fit all of the individual specimens well with an average R2 of 0.95 +/- 0.02 and 0.90 +/- 0.02 (mean +/- SEM) for the AA and AAA groups, respectively. The average Ethetatheta,max at 200 N/m equibiaxial tension was found to be significantly smaller for AAAs as compared to AAs (0.07 +/- 0.01 versus 0.13 +/- 0.03, respectively; p < 0.01). There was also a pronounced increase in the circumferential stiffness for AAA tissue as compared to AA tissue, indicating a larger degree of anisotropy for this tissue as compared to age-matched AA tissue. We also observed that the four-parameter Fung-elastic model was not able to fit the AAA tissue mechanical response using physically realistic material parameter values. It was concluded that aneurysmal degeneration of the abdominal aorta is associated with an increase in mechanical anisotropy, with preferential stiffening in the circumferential direction.

Acute Abdominal Aortic Aneurysms: Cost Analysis of Endovascular Repair and Open Surgery in Hemodynamically Stable Patients with 1-year Follow-up

PURPOSE

To retrospectively assess the in-hospital and 1-year follow-up costs of endovascular aneurysm repair and conventional open surgery in patients with acute infrarenal abdominal aortic aneurysm (AAA) by using a resource-use approach.

MATERIALS AND METHODS

Institutional Review Board approval was obtained, and informed consent was waived. In-hospital costs for all consecutive patients (61 men, six women; mean age, 72.0 years) who underwent endovascular repair (n = 32) or open surgery (n = 35) for acute infrarenal AAA from January 1, 2001, to December 31, 2004, were assessed by using a resource-use approach. Patients who did not undergo computed tomography before the procedure were excluded from analysis. One-year follow-up costs were complete for 30 patients who underwent endovascular repair and for 34 patients who underwent open surgery. Costs were assessed from a health care perspective. Mean costs were calculated for each treatment group and were compared by using the Mann-Whitney U test (alpha = .05). The influence of clinical variables on the total in-hospital cost was investigated by using univariate and multivariate analyses. Costs were expressed in euros for the year 2003.

RESULTS

Sex, age, and comorbidity did not differ between treatment groups (P > .05). The mean total in-hospital costs were lower for patients who underwent endovascular repair than for those who underwent open surgery (euro20 767 vs euro35 470, respectively; P = .004). The total costs, including those for 1-year follow-up, were euro23 588 for patients who underwent endovascular repair and euro36 448 for those who underwent open surgery (P = .05). The results of multivariate analysis indicated that complications had a significant influence on total in-hospital cost; patients who had complications incurred total in-hospital costs that were 2.27 times higher than those for patients who had no complications.

CONCLUSION

Total in-hospital costs and total overall costs, which included 1-year follow-up costs, were lower in patients with acute AAA who underwent endovascular repair than in those who underwent open surgery.

A planar biaxial constitutive relation for the luminal layer of intra-luminal thrombus in abdominal aortic aneurysms

The rupture risk of abdominal aortic aneurysms (AAAs) is thought to be associated with increased levels of wall stress. Finite element analysis (FEA) allows the prediction of wall stresses in a patient-specific, non-invasive manner. We have recently shown that it is important to include the intra-luminal thrombus (ILT), present in approximately 70% of AAA, into FEA simulations of AAA. All FEA simulations to date assume an isotropic, homogeneous material behavior for this material. The purpose of this work was to investigate the multi-axial biomechanical behavior of ILT and to derive an appropriate constitutive relation. We performed planar biaxial testing on the luminal layer of nine ILT specimens obtained fresh in the operating room (9 patients, mean age 71+/-4.5 years, mean diameter 5.9+/-0.4 cm), and a constitutive relation was derived from this data. Peak stretch and maximum tangential modulus (MTM) values were recorded for the equibiaxial protocol in both the circumferential (theta) and longitudinal (L) directions. Stress contour plots were used to investigate the presence of mechanical anisotropy, after which an appropriate strain energy function was fit to each of the specimen datasets. The peak stretch values for the luminal layer of the ILT were (mean+/-SEM) 1.18+/-0.02 and 1.13+/-0.02 in the theta and L directions, respectively (p=0.14). The MTM values were 20+/-2 and 23+/-3N/cm(2) in the theta and L directions, respectively (p=0.37). From these results and our observation of the symmetry of the stress contour plots for each specimen, we concluded that the use of an isotropic strain energy function for ILT is appropriate. Each specimen data set was then fit to a second-order polynomial strain energy function of the first invariant of the left Cauchy-Green strain tensor, resulting in an accurate fit (average R(2)=0.92+/-0.02; range 0.80-0.99). Comparison of our previously reported, uniaxially derived constitutive relation with the biaxially derived relation derived here shows large differences in the predicted mechanical response, underscoring the importance of the appropriate experimental methods used to derive constitutive relations. Further work is merited in an effort to produce more accurate predictions of wall stresses in patient-specific AAA, and viscoelastic behaviors of the ILT.

Midterm Survival After Endovascular Versus Open Repair of Infrarenal Aortic Aneurysms

PURPOSE

To report the midterm survival after endovascular repair (ER) of infrarenal aortic aneurysms and to compare the outcomes to contemporaneous patients treated with open repair (OR).

METHODS

Between January 1995 and December 2001, 498 patients were treated for abdominal aortic aneurysm: 289 (52%) underwent OR and 209 (48%) underwent ER at a single center. Preoperative risk factors were graded according to the SVS/AAVS risk stratification. A computerized database was used to record demographic, clinical, and follow-up data.

RESULTS

Significant benefits (p<0.0001) were observed in the ER group in terms of mean procedural time (163+/-66 versus 132+/-61 minutes), mean blood loss (1268+/-923 versus 122.5+/-284 mL), and mean hospital length of stay (16.24+/-13.3 versus 9.3+/-11.6 days). The perioperative mortality for OR and ER patients were, respectively, 5.1% and 1.5% (p=0.04). The mean follow-up was 40 months in the OR group (range 0-85) and 19 months in the ER group (range 2-80). Contact was lost with 31 (6%) patients during the study. No overall survival advantage was observed for OR over ER, and comparison of OR and ER according the risk classifications did not yield any significant differences. No patients died of aneurysm rupture, but 7 ER patients had to be converted to open surgery. The cumulative freedoms from reinterventions at 4 years for the OR and ER groups, respectively, were 87% and 63% (p=0.001). Patients treated by OR had better clinical success (p=0.001). Patients in the ER group without iliac artery aneurysm showed a significant improvement (p=0.035) over patients with aneurysmal iliac arteries.

CONCLUSIONS

Over the 7 years of this study, ER realized its goal: prevention of aneurysm rupture. Despite a greater number of reinterventions for ER patients, no overall survival difference was observed.

A statewide experience with endovascular abdominal aortic aneurysm repair: Rapid diffusion with excellent early results

OBJECTIVE

The purpose of this study was to compare survival and outcomes of endovascular versus open repair of abdominal aortic aneurysms (AAAs) in New York State (NYS).

METHODS

We used the NYS discharge dataset Statewide Planning and Research Cooperative System (SPARCS) to analyze the outcomes of elective admission for nonruptured (International Classification of Diseases-9th revision [ICD-9] 441.4) open aneurysm repair (38.44) and endovascular aneurysm repair (39.71) during the years 2000-2002. The ICD-9 code for endovascular repair was introduced in late 2000, thus capturing 3 months of empiric data for 2000.

RESULTS

There has been a significant increase in the number of AAA procedures performed in NYS (comparing before and after 2000: average, 1419 vs 1701; P =.0001), temporally coinciding with the implementation of training programs after US Food and Drug Administration approval of endovascular grafts and the new payment code. From 2000 to 2002 the number of NYS hospitals performing endovascular repairs increased from 24 to 60. By 2002 there were more endovascular repairs being performed than open repairs (871 vs 783). The target population for these surgical interventions showed interesting differences. In 2002, women had a 43% chance of receiving an endograft, whereas men had a 55% probability. The use of endovascular repair over the observation period was relatively constant in patients younger than 65 years. In patients older than 65 years, and especially those older than 75 years, endovascular use increased substantially, so that by 2002 older patients were more likely to undergo endovascular repair than open repair. Patients who underwent endovascular repair had significantly more hypertension, coronary artery disease, diabetes, and hyperlipidemia than did patients who underwent open repair. Yet the mean length of stay for endovascular procedures was approximately 3.6 days, and for open procedures was about 10.3 days, across all 3 years (P = <.0001). Moreover, patients who underwent endovascular repair had statistically fewer postoperative complications and significantly lower mortality. In-hospital mortality in 2001 was 3.55% for open repair and 1.14% for endovascular repair (P =.0018), and in 2002 these rates were 4.21% versus 0.8% (P <.0001), respectively.

CONCLUSION

This dataset suggests that endovascular AAA repairs are being performed in a patient population with a higher frequency of comorbidities. However, endovascular repairs still are associated with significantly lower in-hospital mortality, fewer postoperative complications, and a dramatically shorter length of stay. These results suggest that, despite the rapid diffusion of this new technique, early perioperative outcomes may be superior to those with conventional open repair. However, prospective clinical studies are needed to confirm these insights, and such studies may require the infrastructure of consortia of hospitals or society-based registries.

Abdominal aortic aneurysms: elective endovascular repair versus conventional surgery--evaluation with evidence-based medicine techniques

PURPOSE

To use evidence-based techniques to compare elective open surgical repair of abdominal aortic aneurysms with endovascular repair by means of stent placement.

MATERIALS AND METHODS

A focused clinical question formed the basis of a literature search. Evidence-based criteria were used to appraise and assign a "level of evidence" to retrieved articles. The following data were determined from the best studies: systemic, local, and/or vascular complications; graft failure rates; blood loss; mortality; length of intensive care and/or hospital stay; mid- and long-term outcomes; cost of endovascular repair versus that of surgery; and eligibility for endovascular repair. Absolute risk reductions and/or increases and numbers needed to treat or harm were calculated.

RESULTS

The best current evidence came from 22 studies, which showed that there is slight, if any, difference between mortality rates of endovascular repair and surgery. Hospital and/or intensive care stay is shorter, blood loss less, and systemic complications fewer (numbers needed to treat, two to 12) with endovascular repair. Some authors reported a significant increase in local and/or vascular complications with endovascular repair (numbers needed to harm, two to six). Graft failure is significantly more common with endovascular repair (numbers needed to harm, four), and substantive adjunctive interventions are needed. Endovascular repair is more expensive than surgery.

CONCLUSION

Elective endovascular repair has short-term benefits compared with surgery. There is slight, if any, difference in mortality. Endovascular repair costs more than surgery. At follow-up, surgical grafts performed better.

Cost-effectiveness of PET in the diagnosis of Alzheimer disease

PURPOSE

To evaluate the cost-effectiveness of positron emission tomography (PET) in the diagnosis of Alzheimer disease (AD) in community-dwelling patients with mild or moderate dementia who present to specialized AD centers.

MATERIALS AND METHODS

A decision-analytic model was used to compare costs and quality-adjusted life years (QALYs) associated with strategies involving single photon emission computed tomography (SPECT), dynamic susceptibility-weighted contrast material-enhanced magnetic resonance (MR) imaging, and PET as functional imaging adjuncts to the standard clinical work-up. Sensitivity analyses were performed to examine changes in test characteristics, health-related quality-of-life survey instruments, therapeutic effectiveness, and treatment rules.

RESULTS

The use of PET to confirm the results of the standard clinical work-up cost more but yielded fewer benefits than a strategy in which dynamic susceptibility-weighted contrast-enhanced MR imaging was substituted for the typically performed structural computed tomography. This relationship remained stable in scenarios in which standard diagnostic work-up accuracy, drug treatment effectiveness, and version of the Health Utilities Index were altered. Dynamic susceptibility-weighted contrast-enhanced MR imaging cost US dollars 598800 per QALY gained (range, US dollars 74400 to US dollars 1.9 million per QALY), compared with the cost of the standard diagnostic work-up. Treating all patients with dementia was the dominant imaging strategy, except when side effects in patients with non-AD-related dementia were modeled. In all scenarios, SPECT yielded fewer benefits than other strategies at a higher cost.

CONCLUSION

PET may have high diagnostic accuracy, but adding it to the standard diagnostic regimen at AD clinics would yield limited, if any, benefits at very high costs.

The principles of cost-effectiveness analysis and their application

The current healthcare environment requires the evaluation of both the costs and benefits of alternative interventions for a given clinical problem. Given the increased interest in the economic evaluation of healthcare interventions, this article briefly defines various forms of economic evaluations and describes some useful steps for conducting appraisals of cost-effectiveness analyses. Studies of competing methods of treatment of abdominal aortic aneurysms greater than 5 cm are used as a clinical example of interest to the readers of this Journal. Rather than actually conducting such an analysis with existing data, we describe the principles for conducting or reviewing an economic analysis with factitious data.

Abdominal aortic aneurysms: cost-effectiveness of elective endovascular and open surgical repair

PURPOSE

To evaluate the cost-effectiveness of elective endovascular and open surgical repair of infrarenal abdominal aortic aneurysms (AAAs) by taking into account short- and long-term outcomes.

MATERIALS AND METHODS

A Markov decision model was developed to evaluate quality-adjusted life-years (QALYs) and lifetime costs of endovascular and open surgical repair. The incremental cost-effectiveness ratio (CER) was calculated for endovascular repair relative to open surgery in a cohort of 70-year-old men with an AAA between 5 and 6 cm in diameter. Clinically effectiveness data were derived from the literature. Cost data were derived from Medicare reimbursement rates, the hospital database, and the literature. One- and multiple-way sensitivity analyses were performed on uncertain model parameters. Costs were converted to year 2000 U.S. dollars; future costs and outcomes were discounted at 3%.

RESULTS

The incremental CER of endovascular repair was 9,905 dollars per QALY. QALYs and lifetime costs were higher for endovascular repair than for open surgery (6.74 vs 6.52 and 39,785 dollars vs 37,606 dollars, respectively). In sensitivity analyses, the incremental CER was insensitive to immediate conversion rate and procedure mortality rate. The incremental CER was sensitive (ie, more than 75,000 dollars per QALY or endovascular repair was ruled out by dominance) to systemic-remote complications, long-term failures, and ruptures.

CONCLUSION

The results suggest that endovascular repair is a cost-effective alternative compared with open surgery for the elective repair of AAA. The benefits and cost-effectiveness are highly dependent on uncertain outcomes, however, particularly long-term failure and rupture rates.

Endovascular versus open surgical elective repair of infrarenal abdominal aortic aneurysm: predictors of patient discharge destination

PURPOSE

To evaluate patient discharge destination after elective endovascular or open surgical repair of infrarenal abdominal aortic aneurysm and to determine predictors for discharge to home or to a rehabilitation center.

MATERIALS AND METHODS

All patients electively treated for infrarenal abdominal aortic aneurysm with endovascular repair (n = 182) or open surgery (n = 274) between January 1997 and September 1999 were included. From the hospital database, information on discharge destination, patient characteristics, complications, and length of stay was retrieved. Multiple logistic regression analysis was performed to determine predictors for discharge to home or to a rehabilitation center.

RESULTS

Patient characteristics did not differ significantly between the treatment groups, with the exception of age (mean age, 75.1 vs 72.9 years in the endovascular and open surgical group, respectively; P =.005). Patient discharge destinations differed significantly between the treatment groups (P =.001). After endovascular procedures, 156 (85.7%) of 182 patients went home and 19 (10.4%) of 182 patients went to a rehabilitation center. After open surgery, 187 (68.2%) of 274 patients went home and 64 (23.4%) of 274 patients went to a rehabilitation center. The odds ratio of discharge to a rehabilitation center, instead of home, following endovascular procedures versus open surgery was 0.23 (95% CI: 0.13, 0.43).

CONCLUSION

Following elective repair of infrarenal abdominal aortic aneurysm, significantly more patients went home after an endovascular procedure than after open surgery. Procedure type was a significant predictor of discharge destination.