Mortality, morbidity, and costs of ruptured and elective abdominal aortic aneurysm repairs in Nova Scotia, Canada

Automatic segmentation of abdominal aortic aneurysms from CT angiography using a context-aware cascaded U-Net

We delineate abdominal aortic aneurysms, including lumen and intraluminal thrombosis (ILT), from contrast-enhanced computed tomography angiography (CTA) data in 70 patients with complete automation. A novel context-aware cascaded U-Net configuration enables automated image segmentation. Notably, auto-context structure, in conjunction with dilated convolutions, anisotropic context module, hierarchical supervision, and a multi-class loss function, are proposed to improve the delineation of ILT in an unbalanced, low-contrast multi-class labeling problem. A quantitative analysis shows that the automated image segmentation produces comparable results with trained human users (e.g., DICE scores of 0.945 and 0.804 for lumen and ILT, respectively). Resultant morphological metrics (e.g., volume, surface area, etc.) are highly correlated to those parameters generated by trained human users. In conclusion, the proposed automated multi-class image segmentation tool has the potential to be further developed as a translational software tool that can be used to improve the clinical management of AAAs.

An unusual presentation of ruptured abdominal aorta aneurysm

Patient: Female, 65

Final Diagnosis: Ruptured abdominal aorta aneursym

Symptoms: —

Medication: —

Clinical Procedure: After surgery the patient was discharged without sequelae

Specialty: Surgery

Cost-effectiveness of intensive smoking cessation therapy among patients with small abdominal aortic aneurysms

INTRODUCTION

Smoking cessation is one of the few available strategies to decrease the risk for expansion and rupture of small abdominal aortic aneurysms (AAAs). The cost-effectiveness of an intensive smoking cessation therapy in patients with small AAAs identified at screening was evaluated.

METHODS

A Markov cohort simulation model was used to compare an 8-week smoking cessation intervention with adjuvant pharmacotherapy and annual revisits vs nonintervention among 65-year-old male smokers with a small AAA identified at screening. The smoking cessation rate was tested in one-way sensitivity analyses in the intervention group (range, 22%-57%) and in the nonintervention group (range, 3%-30%). Literature data on the effect of smoking on AAA expansion and rupture was factored into the model.

RESULTS

The intervention was cost-effective in all tested scenarios and sensitivity analyses. The smoking cessation intervention was cost-effective due to a decreased need for AAA repair and decreased rupture rate even when disregarding the positive effects of smoking cessation on long-term survival. The incremental cost/effectiveness ratio reached the willingness-to-pay threshold value of €25,000 per life-year gained when assuming an intervention cost of > €3250 or an effect of ≤ 1% difference in long-term smoking cessation between the intervention and nonintervention groups. Smoking cessation resulted in a relative risk reduction for elective AAA repair by 9% and for rupture by 38% over 10 years of follow-up.

CONCLUSIONS

An adequate smoking cessation intervention in patients with small AAAs identified at screening can cost-effectively increase long-term survival and decrease the need for AAA repair.

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.

Resource utilization and outcomes: effect of transfer on patients with ruptured abdominal aortic aneurysms

We evaluated the transfer of patients with the diagnosis of a ruptured AAA (rAAA) from community centers to a tertiary care center. Our purpose was to identify factors associated with mortality and outcomes following the open repair of rAAA and to evaluate the differences between transferred and nontransferred patients. All patients who underwent repair of rAAA at our institution between 1995 and 2002 were retrospectively reviewed. Univariate and multivariate analysis was performed to identify patient specific factors on presentation and intraoperatively. Fifty-two patients underwent repair of rAAA, 20 patients were transferred to our institution. The overall mortality rate was 67%. The mortality rates for nontransferred and transferred groups were 69% and 65%, respectively. The incidence of mortality within 24 hr of surgery was significantly higher in the patients who were not transferred, 10 vs. 41% (p < 0.05). Patient-specific factors assessed for impact on survival by logistic regression included decreased body temperature on arrival to our institution (p = 0.02) and free rupture (p = 0.05). Of intraoperative factors tested, low systolic blood pressure was significantly associated with mortality (p = 0.05). No difference in total length of stay was noted. Transfer patients' length of stay in the intensive care unit was significantly greater than that of nontransferred patients (18.8 +/- vs. 7.3 +/- days, p < 0.05). The difference in ICU cost was dollar 36,000 among groups. We found the acceptance of transfer patients from community centers with rAAA did not adversely affect patient survival. Transferred patients had an over twofold increases in ICU days used. The identification of hypothermia was the single independent factor associated with poor survival and may be a marker for transfer selection. Given reduced reimbursements and increased utilization, tertiary care centers will need to consider the economic ramifications of accepting transfer patients with rAAA.

Management of Abdominal Aortic Aneurysms

Abdominal aortic aneurysms (AAAs) are a lethal disease. Ultrasound is the modality of choice for screening patients for AAAs. It is reasonable to screen patients over age 60, particularly men, women with cardiovascular risk factors, smokers, and patients with a family history of AAAs. Patients with small (< 5.5 cm) AAAs should be followed with serial ultrasound. Medical management should focus on treating comorbidities, particularly those that put patients at risk for other cardiovascular diseases. Smoking cessation is mandatory in these patients. Patients with large or symptomatic AAAs should be evaluated for surgery; this includes careful imaging of the abdomen, aggressive treatment of comorbidities, and perioperative beta blockade. Endovascular repair has lower short-term morbidity compared with conventional open repair. Trials assessing long-term results are in progress. Basic science and translational research focusing on the underlying pathogenesis of AAAs will likely pave the way for medical therapies in the future.