Abdominal aortic aneurysm (AAA): cost-effectiveness of screening, surveillance of intermediate-sized AAA, and management of symptomatic AAA

A Case Study of Abdominal Aortic Aneurysm Detection and Critical Vascular Surgery

Abdominal aortic aneurysm, characterized by a persistent dilation exceeding 3 cm or 50% of the aortic diameter, poses a substantial risk, particularly in males over 65. Despite its potentially asymptomatic nature, early detection is imperative due to the elevated mortality rates, reaching 90% following rupture. The presented case involves a 60-year-old male with progressively worsening abdominal pain, a history of cardiovascular disease, hypertension, and smoking. Initial examinations were inconclusive, requiring advanced imaging that revealed a large aneurysmal dilation. Therapeutic measures included endovascular aneurysm repair (EVAR), highlighting the significance of timely intervention. Despite elective surgery risks, mortality rates decrease significantly when the aneurysm diameter surpasses 43 mm. This report stresses the need for primary care physicians to conduct thorough screenings, recognize risk factors, and facilitate prompt referrals for advanced imaging. The case's pivotal lesson lies in the comprehensive management of abdominal aortic aneurysm, showcasing the potential for life-saving interventions and the critical role of early detection in mitigating the severe consequences associated with its rupture.

Deep-learning-based image segmentation for image-based computational hemodynamic analysis of abdominal aortic aneurysms: a comparison study

Computational hemodynamics is increasingly being used to quantify hemodynamic characteristics in and around abdominal aortic aneurysms (AAA) in a patient-specific fashion. However, the time-consuming manual annotation hinders the clinical translation of computational hemodynamic analysis. Thus, we investigate the feasibility of using deep-learning-based image segmentation methods to reduce the time required for manual segmentation. Two of the latest deep-learning-based image segmentation methods, ARU-Net and CACU-Net, were used to test the feasibility of automated computer model creation for computational hemodynamic analysis. Morphological features and hemodynamic metrics of 30 computed tomography angiography (CTA) scans were compared between pre-dictions and manual models. The DICE score for both networks was 0.916, and the correlation value was above 0.95, indicating their ability to generate models comparable to human segmentation. The Bland-Altman analysis shows a good agreement between deep learning and manual segmentation results. Compared with manual (computational hemodynamics) model recreation, the time for automated computer model generation was significantly reduced (from ∼2 h to ∼10 min). Automated image segmentation can significantly reduce time expenses on the recreation of patient-specific AAA models. Moreover, our study showed that both CACU-Net and ARU-Net could accomplish AAA segmentation, and CACU-Net outperformed ARU-Net in terms of accuracy and time-saving.

Computerized Differentiation of Growth Status for Abdominal Aortic Aneurysms: A Feasibility Study

Fast-growing abdominal aortic aneurysms (AAA) have a high rupture risk and poor outcomes if not promptly identified and treated. Our primary objective is to improve the differentiation of small AAAs' growth status (fast versus slow-growing) through a combination of patient health information, computational hemodynamics, geometric analysis, and artificial intelligence. 3D computed tomography angiography (CTA) data available for 70 patients diagnosed with AAAs with known growth status were used to conduct geometric and hemodynamic analyses. Differences among ten metrics (out of ninety metrics) were statistically significant discriminators between fast and slow-growing groups. Using a support vector machine (SVM) classifier, the area under receiving operating curve (AUROC) and total accuracy of our best predictive model for differentiation of AAAs' growth status were 0.86 and 77.50%, respectively. In summary, the proposed analytics has the potential to differentiate fast from slow-growing AAAs, helping guide resource allocation for the management of patients with AAAs.

Abdominal Aortic Aneurysm Detection in Bioelectrical Impedance Cardiovascular Screenings-A Pilot Study

Screening and diagnosing abdominal aortic aneurysms (AAA) are currently dependent on imaging studies such as ultrasound or computed tomography angiography. All imaging studies offer distinct advantages but also suffer from inherent limitations such as examiner dependency or ionizing radiation. Bioelectrical impedance analysis has previously been investigated with respect to its use in the detection of several cardiovascular and renal pathologies. The present pilot study assessed the feasibility of AAA detection based on bioimpedance analysis. In this single-center exploratory pilot study, measurements were conducted among three different cohorts: patients with AAA, end-stage renal disease patients without AAA, and healthy controls. The device used in the study, CombynECG, is an open-market accessible device for segmental bioelectrical impedance analysis. The data was preprocessed and used to train four different machine learning models on a randomized training sample (80% of the full dataset). Each model was then evaluated on a test set (20% of the full dataset). The total sample included 22 patients with AAA, 16 chronic kidney disease patients, and 23 healthy controls. All four models showed strong predictive performance in the test partitions. Specificity ranged from 71.4 to 100%, while sensitivity ranged from 66.7 to 100%. The best-performing model had 100% accuracy for classification when applied to the test sample. Additionally, an exploratory analysis to approximate the maximum AAA diameter was conducted. An association analysis revealed several impedance parameters that might possess predictive ability with respect to aneurysm size. AAA detection via bioelectrical impedance analysis is technically feasible and appears to be a promising technology for large-scale clinical studies and routine clinical screening assessments.

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.

Anticoagulants and reduced thrombus load in abdominal aortic aneurysms assessed with three-dimensional contrast-enhanced ultrasound examination

OBJECTIVE

The relationship between intraluminal thrombus (ILT) and abdominal aortic aneurysm (AAA) growth and rupture risk remains ambiguous. Studies have shown a limited effect of antiplatelet therapy on ILT size, whereas the impact of anticoagulant therapy on ILT is unresolved. This study aims to evaluate an association between antithrombotic therapy and ILT size assessed with three-dimensional contrast-enhanced ultrasound (3D-CEUS) examination in a cohort of patients with AAA.

METHODS

In a cross-sectional study, 309 patients with small AAAs were examined with 3D-CEUS. Patients were divided into three groups based on prescribed antithrombotic therapy: anticoagulant (n = 36), antiplatelet (n = 222), and no antithrombotic therapy (n = 51). Patient ILT size was calculated in volume and thickness and compared between the three groups.

RESULTS

Patients on anticoagulants had a significantly lower estimated marginal mean ILT volume of 16 mL (standard error [SE], ±3.2) compared with 28 mL (SE, ±2.7) in the no antithrombotic group and 30 mL (SE, ±1.3) in the antiplatelet group when adjusting for AAA volume (P < .001) and comorbidities (P < .001). In addition, patients on anticoagulant therapy had significantly lower estimated marginal mean ILT thickness of 10 mm (SE, ±1.1) compared with 13 mm (SE, ±0.9) in the no antithrombotic group of and 13mm (SE, ±0.4) in the antiplatelet group when adjusting for AAA diameter (P = .03) and comorbidities (P = .035).

CONCLUSIONS

A 3D-CEUS examination is applicable for ILT assessment and demonstrates that patients with AAA on anticoagulant therapy have lower ILT thickness and volume than patients with AAA on antiplatelet therapy and those without antithrombotic therapy. Causality between anticoagulants and ILT size, and extrapolation to AAA growth and rupture risk, is unknown and merits further investigations, to further nuance US-based AAA surveillance strategy.

Priorities among effective clinical preventive services in British Columbia, Canada

Background

Despite the long-standing experience of rating the evidence for clinical preventive services, the delivery of effective clinical preventive services in Canada and elsewhere is less than optimal. We outline an approach used in British Columbia to assist in determining which effective clinical preventive services are worth doing.

Methods

We calculated the clinically preventable burden and cost-effectiveness for 28 clinical preventive services that received a ‘strong or conditional (weak) recommendation for’ by the Canadian Task Force on Preventive Health Care or an ‘A’ or ‘B’ rating by the United States Preventive Services Task Force. Clinically preventable burden is the total quality adjusted life years that could be gained if the clinical preventive services were delivered at recommended intervals to a British Columbia birth cohort of 40,000 individuals over the years of life that the service is recommended. Cost-effectiveness is the net cost per quality adjusted life year gained.

Results

Clinical preventive services with the highest population impact and best value for money include services that address tobacco use in adolescents and adults, exclusive breastfeeding, and screening for hypertension and other cardiovascular disease risk factors followed by appropriate pharmaceutical treatment. In addition, alcohol misuse screening and brief counseling, one-time screening for hepatitis C virus infection in British Columbia adults born between 1945 and 1965, and screening for type 2 diabetes approach these high-value clinical preventive services.

Conclusions

These results enable policy makers to say with some confidence what preventive manoeuvres are worth doing but further work is required to determine the best way to deliver these services to all those eligible and to establish what supportive services are required. After all, if a clinical preventive service is worth doing, it is worth doing well.

Tryptophan Catabolism and Inflammation: A Novel Therapeutic Target For Aortic Diseases

Aortic diseases are the primary public health concern. As asymptomatic diseases, abdominal aortic aneurysm (AAA) and atherosclerosis are associated with high morbidity and mortality. The inflammatory process constitutes an essential part of a pathogenic cascade of aortic diseases, including atherosclerosis and aortic aneurysms. Inflammation on various vascular beds, including endothelium, smooth muscle cell proliferation and migration, and inflammatory cell infiltration (monocytes, macrophages, neutrophils, etc.), play critical roles in the initiation and progression of aortic diseases. The tryptophan (Trp) metabolism or kynurenine pathway (KP) is the primary way of degrading Trp in most mammalian cells, disturbed by cytokines under various stress. KP generates several bioactive catabolites, such as kynurenine (Kyn), kynurenic acid (KA), 3-hydroxykynurenine (3-HK), etc. Depends on the cell types, these metabolites can elicit both hyper- and anti-inflammatory effects. Accumulating evidence obtained from various animal disease models indicates that KP contributes to the inflammatory process during the development of vascular disease, notably atherosclerosis and aneurysm development. This review outlines current insights into how perturbed Trp metabolism instigates aortic inflammation and aortic disease phenotypes. We also briefly highlight how targeting Trp metabolic pathways should be considered for treating aortic diseases.

Cost-effectiveness of a population-based AAA screening program for men over 65 years old in Iran

BACKGROUND

Screening program tend to recognized patients in their early stage and consequently improve health outcomes. Cost-effectiveness of the abdominal aortic aneurysm (AAA) screening program has been scarcely studied in developing countries. We sought to evaluate the cost-effectiveness of a screening program for the abdominal aortic aneurysm (AAA) in men aged over 65 years in Iran.

METHODS

A Markov cohort model with 11 mutually exclusive health statuses was used to evaluate the cost-effectiveness of a population-based AAA screening program compared with a no-screening strategy. Transitions between the health statuses were simulated by using 3-month cycles. Data for disease transition probabilities and quality of life outcomes were obtained from published literature, and costs were calculated based on the price of medical services in Iran and the examination of the patients' medical records. The outcomes were life-years gained, the quality-adjusted life-year (QALY), costs, and the incremental cost-effectiveness ratio (ICER). The analysis was conducted for a lifetime horizon from the payer's perspective. Costs and effects were discounted at an annual rate of 3%. Uncertainty surrounding the model inputs was tested with deterministic and probabilistic sensitivity analyses.

RESULTS

The mean incremental cost of the AAA screening strategy compared with the no-screening strategy was $140 and the mean incremental QALY gain was 0.025 QALY, resulting in an ICER of $5566 ($14,656 PPP) per QALY gained. At a willingness-to-pay of 1 gross domestic product (GDP) per capita ($5628) per QALY gained, the probability of the cost-effectiveness of AAA screening was about 50%. However, at a willingness-to-pay of twice the GDP per capita per QALY gained, there was about a 95% probability for the AAA screening program to be cost-effective in Iran.

CONCLUSIONS

The results of this study showed that at a willingness-to-pay of 1 GDP per capita per QALY gained, a 1-time AAA screening program for men aged over 65 years could not be cost-effective. Nevertheless, at a willingness-to-pay of twice the GDP per capita per QALY gained, the AAA screening program could be cost-effective in Iran. Further, AAA screening in high-risk groups could be cost-effective at a willingness-to-pay of 1 GDP per capita per QALY gained.

[Opportunistic screening for abdominal aortic aneurysm during echocardiography in patients with coronary artery disease: Utility or futility?]

Abdominal aortic aneurysm is a chronic degenerative disease that is usually silent until rupture occurs and this complication is still associated in contemporary era with a high rate of mortality. Screening programmes for abdominal aortic aneurysm have been shown to be effective in reducing global mortality in the screened population but these programmes are poorly implemented in the Western countries. As coronary artery disease and abdominal aorta aneurysmal disease share many risk factors, the cardiologist is centrally positioned in the screening strategy, not only to identify patients with higher risk of developing abdominal aortic aneurysm, but also to perform an opportunistic screening during echocardiography. This paper summarises evidence about the feasibility, indications, modalities, benefits and risks related to the opportunistic screening for abdominal aortic aneurysm during echocardiography with a particular emphasis on the population of patients with coronary artery disease.

IFI16 contributes to the pathogenesis of abdominal aortic aneurysm by regulating the caspase-1/IL-1β/MCPIP1 pathway

AIMS

Abdominal aortic aneurysm (AAA) is a multi-factorial progressive vascular disease characterized by chronic inflammatory cell infiltration. We investigated the roles played by IFI16 and ASC inflammasomes in AAA development and progression.

MATERIALS AND METHODS

Western blot and qRT-PCR studies were performed to analyze the expression of relative genes in AAA specimens and mouse vascular smooth muscle cells (VSMCs). The apoptosis rates and ROS levels of VSMCs were assessed by flow cytometry. Transwell assays were performed to analyze the migration ability of VSMCs. The levels of MCP-1, IL-1β, and IL-6 in the supernatants of cultured VSMCs were analyzed by ELISA.

KEY FINDINGS

Increased levels of IFI16 expression were found in AAA specimens and Ang-II-treated VSMCs. IFI16 and ASC silencing suppressed the apoptosis and migration ability of VSMCs undergoing Ang-II treatment, reduced elasticity damage to the aortic wall, and decreased the levels of MMP expression. The effect of IFI16 knockdown in Ang-II-induced VSMCs was reversed by MCPIP1 overexpression.

SIGNIFICANCE

Our data suggest that an up-regulation of IFI16 and ASC expression might promote the apoptosis of VSMCs, enhance the inflammatory response, and impairs vascular wall elasticity via a MCPIP1-related mechanism. The inflammasome components IFI16 and ASC might be involved in AAA progression and serve as target molecules for diagnosing and treating AAA.

Cardiac evaluation of young athletes: Time for a risk-based approach?

Pre‐participation cardiovascular screening (PPCS) is recommended by several scientific and sporting organizations on the premise that early detection of cardiac disease provides a platform for individualized risk assessment and management; which has been proven to lower mortality rates for certain conditions associated with sudden cardiac arrest (SCA) and sudden cardiac death (SCD). What constitutes the most effective strategy for PPCS of young athletes remains a topic of considerable debate. The addition of the electrocardiogram (ECG) to the medical history and physical examination undoubtedly enhances early detection of disease, which meets the primary objective of PPCS. The benefit of enhanced sensitivity must be carefully balanced against the risk of potential harm through increased false‐positive findings, costly downstream investigations, and unnecessary restriction/disqualification from competitive sports. To mitigate this risk, it is essential that ECG‐based PPCS programs are implemented by institutions with a strong infrastructure and by physicians appropriately trained in modern ECG standards with adequate cardiology resources to guide downstream investigations. While PPCS is compulsory for most competitive athletes, the current debate surrounding ECG‐based programs exists in a binary form; whereby ECG screening is mandated for all competitive athletes or none at all. This polarized approach fails to consider individualized patient risk and the available sports cardiology resources. The limitations of a uniform approach are highlighted by evolving data, which suggest that athletes display a differential risk profile for SCA/SCD, which is influenced by age, sex, ethnicity, sporting discipline, and standard of play. Evaluation of the etiology of SCA/SCD within high‐risk populations reveals a disproportionately higher prevalence of ECG‐detectable conditions. Selective ECG screening using a risk‐based approach may, therefore, offer a more cost‐effective and feasible approach to PPCS in the setting of limited sports cardiology resources, although this approach is not without important ethical considerations.

Association of hernia with subsequent aortic aneurysm in geriatric patients

OBJECTIVE

Although inguinal hernia and aortic aneurysm share similar pathogenic mechanisms of collagen and elastin destruction, their clinical association in geriatric patients is inconclusive. We assessed the association between hernia and the subsequent occurrence of aortic aneurysm in geriatric patients.

METHODS

Adult patients with hernias between 2000 and 2012 were identified from a longitudinal claims database of 1 million beneficiaries from Taiwan's National Health Insurance program, and a control group of patients without hernia were matched by propensity score in a ratio of 1:3. Patients previously diagnosed with aortic aneurysms or connective tissue diseases were excluded. Follow-up ended on December 31, 2013. The incidence rate of aortic aneurysm was compared between patients with hernia and those without. Cox proportional hazards models were used to estimate relative hazards.

RESULTS

After propensity score matching, there were 16,933 patients with hernia (aged 20-64 years: 10,326; ≥65 years: 6607) and 50,799 patients without hernia (aged 20-64: 30,978; ≥65: 19,821). Patients with hernia had a greater incidence rate and hazard ratio of aortic aneurysm than did patients without hernia (6.4 vs 4.8/10,000 person-years; adjusted subdistribution hazard ratio [sdHR], 1.34; 95% confidence interval [CI], 1.02-1.76; P = .03), especially for those aged ≥65 years (15.6 vs 10.4/10,000 person-years; adjusted sdHR, 1.44; 95% CI, 1.07-1.94; P = .01) In addition, geriatric patients with hernia were associated with a marginally greater risk of thoracic (adjusted sdHR, 1.66; 95% CI, 0.96-2.86) and abdominal (adjusted sdHR, 1.36; 95% CI, 0.96-1.94) aortic aneurysm rupture.

CONCLUSIONS

Geriatric patients with hernia were associated with a greater incidence of aortic aneurysm than were those without.

A preclinical ultrasound method for the assessment of vascular disease progression in murine models

Introduction

The efficacy of preclinical ultrasound at providing a quantitative assessment of mouse models of vascular disease is relatively unknown. In this study, preclinical ultrasound was used in combination with a semi-automatic image processing method to track arterial distension alterations in mouse models of abdominal aortic aneurysm and atherosclerosis.

Methods

Longitudinal B-mode ultrasound images of the abdominal aorta were acquired using a preclinical ultrasound scanner. Arterial distension was assessed using a semi-automatic image processing algorithm to track vessel wall motion over the cardiac cycle. A standard, manual analysis method was applied for comparison.

Results

Mean arterial distension was significantly lower in abdominal aortic aneurysm mice between day 0 and day 7 post-onset of disease (p < 0.01) and between day 0 and day 14 (p < 0.001), while no difference was observed in sham control mice. Manual analysis detected a significant decrease (p < 0.05) between day 0 and day 14 only. Atherosclerotic mice showed alterations in arterial distension relating to genetic modification and diet. Arterial distension was significantly lower (p < 0.05) in Ldlr^-/- (++/--) mice fed high-fat western diet when compared with both wild type (++/++) mice and Ldlr^-/- (++/--) mice fed chow diet. The manual method did not detect a significant difference between these groups.

Conclusions

Arterial distension can be used as an early marker for the detection of arterial disease in murine models. The semi-automatic analysis method provided increased sensitivity to differences between experimental groups when compared to the manual analysis method.

After 50 Years of Heart Transplants: What Does the Next 50 Years Hold for Cardiovascular Medicine? A Perspective From the International Society for Applied Cardiovascular Biology

The first successful heart transplant 50 years ago by Dr.Christiaan Barnard in Cape Town, South Africa revolutionized cardiovascular medicine and research. Following this procedure, numerous other advances have reduced many contributors to cardiovascular morbidity and mortality; yet, cardiovascular disease remains the leading cause of death globally. Various unmet needs in cardiovascular medicine affect developing and underserved communities, where access to state-of-the-art advances remain out of reach. Addressing the remaining challenges in cardiovascular medicine in both developed and developing nations will require collaborative efforts from basic science researchers, engineers, industry, and clinicians. In this perspective, we discuss the advancements made in cardiovascular medicine since Dr. Barnard's groundbreaking procedure and ongoing research efforts to address these medical issues. Particular focus is given to the mission of the International Society for Applied Cardiovascular Biology (ISACB), which was founded in Cape Town during the 20th celebration of the first heart transplant in order to promote collaborative and translational research in the field of cardiovascular medicine.

CD1d deficiency inhibits the development of abdominal aortic aneurysms in LDL receptor deficient mice

An abdominal aortic aneurysm (AAA) is a dilatation of the abdominal aorta leading to serious complications and mostly to death. AAA development is associated with an accumulation of inflammatory cells in the aorta including NKT cells. An important factor in promoting the recruitment of these inflammatory cells into tissues and thereby contributing to the development of AAA is angiotensin II (Ang II). We demonstrate that a deficiency in CD1d dependent NKT cells under hyperlipidemic conditions (LDLr^-/-CD1d^-/- mice) results in a strong decline in the severity of angiotensin II induced aneurysm formation when compared with LDLr^-/- mice. In addition, we show that Ang II amplifies the activation of NKT cells both in vivo and in vitro. We also provide evidence that type I NKT cells contribute to AAA development by inducing the expression of matrix degrading enzymes in vSMCs and macrophages, and by cytokine dependently decreasing vSMC viability. Altogether, these data prove that CD1d-dependent NKT cells contribute to AAA development in the Ang II-mediated aneurysm model by enhancing aortic degradation, establishing that therapeutic applications which target NKT cells can be a successful way to prevent AAA development.

Emergency Computed Tomography Angiogram of the Chest, Abdomen, and Pelvis

In the setting of blunt trauma, the rapid assessment of internal injuries is essential to prevent potentially fatal outcomes. Computed tomography is a useful diagnostic tool for both screening and diagnosis. In addition to trauma, acute chest syndromes often warrant emergent computed tomographic angiography, looking for etiologies such as aortic aneurysms or complications of aortic aneurysms, or both, pulmonary emboli, as well as other acute vascular process like aortic dissection and Takayasu aortitis. With continued improvements in diagnostic imaging, computed tomographic angiography of the chest, abdominal and pelvis proves to be an effective modality to image the aorta and other major vascular structures.

Abnormal kynurenine pathway of tryptophan catabolism in cardiovascular diseases

Kynurenine pathway (KP) is the primary path of tryptophan (Trp) catabolism in most mammalian cells. The KP generates several bioactive catabolites, such as kynurenine (Kyn), kynurenic acid (KA), 3-hydroxykynurenine (3-HK), xanthurenic acid (XA), and 3-hydroxyanthranilic acid (3-HAA). Increased catabolite concentrations in serum are associated with several cardiovascular diseases (CVD), including heart disease, atherosclerosis, and endothelial dysfunction, as well as their risk factors, including hypertension, diabetes, obesity, and aging. The first catabolic step in KP is primarily controlled by indoleamine 2,3-dioxygenase (IDO) and tryptophan 2,3-dioxygenase (TDO). Following this first step, the KP has two major branches, one branch is mediated by kynurenine 3-monooxygenase (KMO) and kynureninase (KYNU) and is responsible for the formation of 3-HK, 3-HAA, and quinolinic acid (QA); and another branch is controlled by kynurenine amino-transferase (KAT), which generates KA. Uncontrolled Trp catabolism has been demonstrated in distinct CVD, thus, understanding the underlying mechanisms by which regulates KP enzyme expression and activity is paramount. This review highlights the recent advances on the effect of KP enzyme expression and activity in different tissues on the pathological mechanisms of specific CVD, KP is an inflammatory sensor and modulator in the cardiovascular system, and KP catabolites act as the potential biomarkers for CVD initiation and progression. Moreover, the biochemical features of critical KP enzymes and principles of enzyme inhibitor development are briefly summarized, as well as the therapeutic potential of KP enzyme inhibitors against CVD is briefly discussed.

The use of pre-existing CT imaging in screening for abdominal aortic aneurysms

Ultrasound screening for abdominal aortic aneurysm (AAA) is recommended for male smokers >65 years of age, but screening rates remain low. If computed tomography (CT) performed for other indications could be considered adequate for screening, one-third of ultrasounds would potentially be unnecessary, and overall screening rates would be substantially higher. The objective of this study was to evaluate the sensitivity of CT imaging of the abdomen for the detection of AAA when performed for other clinical indications. We performed a retrospective study of patients eligible for AAA screening who had undergone an abdominal ultrasound as well as an abdominal CT scan for other indications within 3 years prior to that study. The primary outcome was identification of an AAA, recorded in the findings narrative or impression of the CT scan report. Of 142 patients with both a CT scan and an AAA on ultrasound, 127 (89.4%) were noted to have an AAA in the report of a CT scan performed within the 3 years prior to the ultrasound. An additional 10 films demonstrated an AAA that was not mentioned in the report. The sensitivity of pre-existing CT scans for AAA screening was 97.2% (137/141) [95% CI: 93.4–99.0%]; 123 (86.6%) of these positive findings were reported in the findings narrative and 120 (84.5%) were reported in the radiologist’s final impression. The sensitivity for AAA identification in the report of a pre-existing CT scan of the abdomen performed for alternate indications appears high enough to use as a screening test. When radiologists note an AAA, they should be sure to include it in the final impression.

Cost-effectiveness of Screening for Abdominal Aortic Aneurysm in Combination with Medical Intervention in Patients with Small Aneurysms

OBJECTIVES

Screening for abdominal aortic aneurysm (AAA) among 65 year old men has been proven cost-effective, but nowadays is conducted partly under new conditions. The prevalence of AAA has decreased, and endovascular aneurysm repair (EVAR) has become the predominant surgical method for AAA repair in many centers. At the Malmö Vascular Center pharmacological secondary prevention with statins, antiplatelet therapy, and blood pressure reduction is initiated and given to all patients with AAA. This study evaluates the cost-effectiveness of AAA screening under the above mentioned conditions.

METHODS

This was a Markov cohort simulation. A total of 4,300 65 year old men were invited to annual AAA screening; the attendance rate was 78.3% and AAA prevalence was 1.8%. A Markov model with 11 health states was used to evaluate cost-effectiveness of AAA screening. Background data on rupture risks, costs, and effectiveness of surgical interventions were obtained from the participating unit, the national Swedvasc Registry, and from the scientific literature.

RESULTS

The additional costs of the screening strategy compared with no screening were €169 per person and year. The incremental health gain per subject in the screened cohort was 0.011 additional quality adjusted life years (QALYs), corresponding to an incremental cost-effectiveness ratio (ICER) of €15710 per QALY. Assuming a 10% reduction of all cause mortality, the incremental cost of screening was €175 per person and year. The gain per subject in the screened cohort was 0.013 additional QALYs, corresponding to an ICER of €13922 per QALY CONCLUSIONS: AAA screening remains cost-effective according to both the Swedish recommendations and the UK National Institute for Health and Care Excellence recommendations in the new era of lower AAA prevalence, EVAR as the predominant surgical method, and secondary prevention for all AAA patients.

A large un-ruptured abdominal aortic aneurysm causing pulmonary embolism

A 79 years old woman presented in a peripheral hospital with dyspnea, right-sided pleuritic chest pain and cough for 3 days. On examination, she was tachycardiac and tachypneic. She had reduced air entry bilaterally on auscultation. Computed tomography-pulmonary angiogram, performed in peripheral Hospital, confirmed the diagnosis of pulmonary embolism, and she was commenced on warfarin. Ultrasonography showed no evidence of deep venous thrombosis in legs; however, ultrasound of the abdomen revealed an aortic aneurysm. She was hemodynamically stable on transfer to vascular surgery department, and her complete clinical examination revealed a pulsatile mass in the central abdomen. Computed tomography angiogram of aorta showed 8.7-cm abdominal aortic aneurysm. Venogram performed during inferior vena cava (IVC) filter insertion showed that IVC was displaced and compressed due to this large aortic aneurysm, causing thromboembolism. An open repair of the aneurysm was performed with uneventful recovery.

Scientific second-order 'nudging' or lobbying by interest groups: the battle over abdominal aortic aneurysm screening programmes

The idea that it is acceptable to 'nudge' people to opt for the 'healthy choice' is gaining currency in health care policy circles. This article investigates whether researchers evaluating Abdominal Aortic Aneurysm Screening Programmes (AAASP) attempt to influence decision makers in ways that are similar to popular 'nudging' techniques. Comparing two papers on the health economics of AAASP both published in the BMJ within the last 3 years, it is shown that the values chosen for the health economics modelling are not representative of the literature and consistently favour the conclusions of the articles. It is argued (1) that this and other features of these articles may be justified within a Libertarian Paternalist framework as 'nudging' like ways of influencing decision makers, but also (2) that these ways of influencing decision makers raise significant ethical issues in the context of democratic decision making.

Abdominal aortic aneurysm in a patient with low back pain

STUDY DESIGN

Resident's case problem.

BACKGROUND

The purpose of this report was to describe (1) the clinical reasoning that led a clinician to identify an abdominal aortic aneurysm (AAA) in a patient with low back pain requiring immediate medical referral, and (2) an evidence-based approach to clinical evaluation of patients with suspected AAA.

DIAGNOSIS

The patient was unable to identify a specific mechanism of injury for his low back pain, lacked aggravating/easing factors for his symptoms, and complained of night pain and an inability to ease his symptoms with position changes. While the patient's symptoms remained unchanged during physical examination of the lumbar spine and hip, abdominal palpation revealed a strong, nontender pulsation over the midline of the upper and lower abdominal quadrants. Due to concern for an AAA, the patient was immediately referred to his physician. Subsequent computed tomography imaging revealed a prominent AAA, which measured up to 5.5 cm in greatest dimension and extended from below the renal arteries to the bifurcation of the iliac arteries. The patient initially deferred surgical intervention but eventually consented 6 months later, after repeat computed tomography imaging revealed that the AAA had progressed to 6.7 cm in greatest dimension.

DISCUSSION

It is essential for physical therapists to be familiar with a diagnostic pathway to help identify AAA in patients presenting with apparent musculoskeletal complaints. Knowledge of the risk factors for AAA, understanding how to screen for nonmusculoskeletal symptoms, and a basic competence in abdominal palpation and how to interpret findings will help with the clinician's clinical decision making.

LEVEL OF EVIDENCE

Differential diagnosis, level 4. J Orthop Sports Phys Ther 2014;44(7):500-507. Epub 25 April 2014. doi:10.2519/jospt.2014.4935.

Locally applied leptin induces regional aortic wall degeneration preceding aneurysm formation in apolipoprotein E-deficient mice

OBJECTIVE

Leptin promotes atherosclerosis and vessel wall remodeling. As abdominal aortic aneurysm (AAA) formation involves tissue remodeling, we hypothesized that local leptin synthesis initiates and promotes this process.

METHODS AND RESULTS

Human surgical AAA walls were analyzed for antigen and mRNA levels of leptin and leptin receptor, as well as mRNA for matrix metalloproteinases (MMP)-9 and MMP-12. Leptin and leptin receptor antigen were evident in all AAAs, and leptin, MMP-9, and MMP-12 mRNA was increased relative to age-matched nondilated controls. To simulate in vivo local leptin synthesis, ApoE(-/-) mice were subjected to a paravisceral periaortic application of low-dose leptin. Leptin-treated aortas exhibited decreased transforming growth factor-β and increased MMP-9 mRNA levels 5 days after surgery, and leptin receptor mRNA was upregulated by day 28. Serial ultrasonography demonstrated accelerated regional aortic diameter growth after 28 days, correlating with local medial degeneration, increased MMP-9, MMP-12, and periadventitial macrophage clustering. Furthermore, the combination of local periaortic leptin and systemic angiotensin II administration augmented medial MMP-9 synthesis and aortic aneurysm size.

CONCLUSIONS

Leptin is locally synthesized in human AAA wall. Paravisceral aortic leptin in ApoE(-/-) mice induces local medial degeneration and augments angiotensin II-induced AAA, thus suggesting novel mechanistic links between leptin and AAA formation.

Cost effectiveness of abdominal aortic aneurysm screening and rescreening in men in a modern context: evaluation of a hypothetical cohort using a decision analytical model

OBJECTIVE

To assess the cost effectiveness of different screening strategies for abdominal aortic aneurysm in men, from the perspective of a national health service.

SETTING

Screening units at regional hospitals.

PARTICIPANTS

Hypothetical cohort of 65 year old men from the general population.

MAIN OUTCOME MEASURES

Costs (£ in 2010) and effect on health outcomes (quality adjusted life years (QALYs)).

RESULTS

Screening seems to be highly cost effective compared with not screening. The model estimated a 92% probability that some form of screening would be cost effective at a threshold of £20,000 (€24,790; $31,460). If men with an aortic diameter of 25-29 mm at the initial screening were rescreened once after five years, 452 men per 100,000 initially screened would benefit from early detection, whereas lifetime rescreening every five years would detect 794 men per 100,000. We estimated the associated incremental cost effectiveness ratios for rescreening once and lifetime rescreening to be £10,013 and £29,680 per QALY, respectively. The individual probability of being the most cost effective strategy was higher for each rescreening strategy than for the screening once strategy (in view of the £20,000 threshold).

CONCLUSIONS

This study confirms the cost effectiveness of screening versus no screening and lends further support to considerations of rescreening men at least once for abdominal aortic aneurysm.

Roles for specialty societies and vascular surgeons in accountable care organizations

With the passage of the Affordable Care Act, accountable care organizations (ACOs) represent a new paradigm in healthcare payment reform. Designed to limit growth in spending while preserving quality, these organizations aim to incant physicians to lower costs by returning a portion of the savings realized by cost-effective, evidence-based care back to the ACO. In this review, first, we will explore the development of ACOs within the context of prior attempts to control Medicare spending, such as the sustainable growth rate and managed care organizations. Second, we describe the evolution of ACOs, the demonstration projects that established their feasibility, and their current organizational structure. Third, because quality metrics are central to the use and implementation of ACOs, we describe current efforts to design, collect, and interpret quality metrics in vascular surgery. And fourth, because a "seat at the table" will be an important key to success for vascular surgeons in these efforts, we discuss how vascular surgeons can participate and lead efforts within ACOs.

Evidence for the Credibility of Health Economic Models for Health Policy Decisionmaking: A Systematic Literature Review of Screening for Abdominal Aortic Aneurysms

Objective

To investigate whether the credibility of health economic models of screening for abdominal aortic aneurysms for health policy decisionmaking has improved since 2005 when a systematic review by Campbell et al. concluded that reporting standards were poor and there was divergence between the findings of studies that was hard to explain.

Methods

A systematic literature review was carried out following PRISMA reporting principles. Health economic models of the cost-effectiveness of screening for abdominal aortic aneurysms published between 2005-2010 were included. Key characteristics were extracted and the models were assessed for quality against guidelines for best practice by a multidisciplinary team.

Results

Seven models were identified and found to provide divergent guidance. Only three reports met 10 of the 15 quality criteria.

Conclusions

Researchers in the field seem to have benefited from general advances in health economic modelling and some improvements in reporting were noted. However, the low level of agreement between studies in model structures and assumptions, and difficulty in justifying these (convergent validity), remain a threat to the credibility of health economic models. Decision-makers should not accept the results of a modelling study if the methods are not fully transparent and justified. Modellers should, whenever relevant, supplement a primary report of results with a technical report detailing and discussing the methodological choices made.

Analysis of risk factors for abdominal aortic aneurysm in a cohort of more than 3 million individuals

BACKGROUND

Abdominal aortic aneurysm (AAA) disease is an insidious condition with an 85% chance of death after rupture. Ultrasound screening can reduce mortality, but its use is advocated only for a limited subset of the population at risk.

METHODS

We used data from a retrospective cohort of 3.1 million patients who completed a medical and lifestyle questionnaire and were evaluated by ultrasound imaging for the presence of AAA by Life Line Screening in 2003 to 2008. Risk factors associated with AAA were identified using multivariable logistic regression analysis.

RESULTS

We observed a positive association with increasing years of smoking and cigarettes smoked and a negative association with smoking cessation. Excess weight was associated with increased risk, whereas exercise and consumption of nuts, vegetables, and fruits were associated with reduced risk. Blacks, Hispanics, and Asians had lower risk of AAA than whites and Native Americans. Well-known risk factors were reaffirmed, including male gender, age, family history, and cardiovascular disease. A predictive scoring system was created that identifies aneurysms more efficiently than current criteria and includes women, nonsmokers, and individuals aged <65 years. Using this model on national statistics of risk factors prevalence, we estimated 1.1 million AAAs in the United States, of which 569,000 are among women, nonsmokers, and individuals aged <65 years.

CONCLUSIONS

Smoking cessation and a healthy lifestyle are associated with lower risk of AAA. We estimated that about half of the patients with AAA disease are not eligible for screening under current guidelines. We have created a high-yield screening algorithm that expands the target population for screening by including at-risk individuals not identified with existing screening criteria.

Long-term benefit and cost-effectiveness analysis of screening for abdominal aortic aneurysms from a randomized controlled trial

Background

The aim was to estimate long-term mortality benefits and cost-effectiveness of screening for abdominal aortic aneurysm (AAA) in men aged 64–73 years.

Methods

All men aged 64–73 years living in Viborg County were randomized to be controls (n = 6306) or invited for abdominal ultrasonography at a regional hospital (n = 6333). Mortality and AAA-related interventions were recorded in national databases. The cost of initial screening was based on actual costs of the programme. Incremental cost-effectiveness ratios (ICERs) were calculated on gains in life years and Quality Adjusted Life Years (QALY). Discounting (3 per cent) was applied to both costs and effects, and all costs were adjusted to euros at 2007 prices.

Results

The relative risk reduction of the screening programme in AAA-related mortality was 66 per cent (hazard ratio 0·34, 95 per cent confidence interval (c.i.) 0·20 to 0·57). The corresponding risk reduction in all-cause mortality was 2 per cent (hazard ratio 0·98, 95 per cent c.i. 0·93 to 1·03). The ICER was estimated at €157 (−3292 to 4401) per life year gained and €179 (−4083 to 4682) per QALY gained. Screening was found to be cost effective at a probability above 0·97 for a willingness-to-pay threshold of only €5000. One-way sensitivity analysis demonstrated that this result was robust to various alternative assumptions, as the probability did not drop below 0·90 for any scenario.

Conclusion

The mortality benefit of screening for AAA in men aged 64–73 years was maintained in the longer term and screening was cost effective. Registration number: ISRCTN65822028 (http://www.controlled-trials.com).

Analysis of cost effectiveness of screening Danish men aged 65 for abdominal aortic aneurysm

OBJECTIVE

To assess the cost effectiveness of screening men aged 65 for abdominal aortic aneurysm.

DESIGN

Cost effectiveness analysis based on a probabilistic, enhanced economic decision analytical model from screening to death.

POPULATION AND SETTING

Hypothetical population of men aged 65 invited (or not invited) for ultrasound screening in the Danish healthcare system.

DATA SOURCES

Published results from randomised trials and observational epidemiological studies retrieved from electronic bibliographic databases, and supplementary data obtained from the Danish Vascular Registry.

DATA SYNTHESIS

A hybrid decision tree and Markov model was developed to simulate the short term and long term effects of screening for abdominal aortic aneurysm compared with no systematic screening on clinical and cost effectiveness outcomes. Probabilistic sensitivity analyses using Monte Carlo simulation were carried out. Results were presented in a cost effectiveness acceptability curve, an expected value of perfect information curve, and a curve showing the expected (net) number of avoided deaths from abdominal aortic aneurysm over time after the introduction of screening. The model was validated by calibrating base case health outcomes and expected activity levels against evidence from the recent Cochrane review of screening for abdominal aortic aneurysm.

RESULTS

The estimated costs per quality adjusted life year (QALY) gained discounted at 3% per year over a lifetime for costs and QALYs was pound43 485 (euro54,852; $71,160). At a willingness to pay threshold of pound30,000 the probability of screening for abdominal aortic aneurysm being cost effective was less than 30%. One way sensitivity analyses showed the incremental cost effectiveness ratio varying from pound32,640 to pound66,001 per QALY.

CONCLUSION

Screening for abdominal aortic aneurysm does not seem to be cost effective. Further research is needed on long term quality of life outcomes and costs.

Is population screening for abdominal aortic aneurysm cost-effective?

BACKGROUND

Ruptured abdominal aortic aneurysm (AAA) is responsible for 1-2% of all male deaths over the age of 65 years. Early detection of AAA and elective surgery can reduce the mortality risk associated with AAA. However, many patients will not be diagnosed with AAA and have therefore an increased death risk due to the untreated AAA. It has been suggested that population screening for AAA in elderly males is effective and cost-effective. The purpose of this study was to perform a systematic review of published cost-effectiveness analyses of screening elderly men for AAA.

METHODS

We performed a systematic search for economic evaluations in NHSEED, EconLit, Medline, Cochrane, Embase, Cinahl and two Scandinavian HTA data bases (DACEHTA and SBU). All identified studies were read in full and each study was systematically assessed according to international guidelines for critical assessment of economic evaluations in health care.

RESULTS

The search identified 16 cost-effectiveness studies. Most studies considered only short term cost consequences. The studies seemed to employ a number of "optimistic" assumptions in favour of AAA screening, and included only few sensitivity analyses that assessed less optimistic assumptions.

CONCLUSION

Further analyses of cost-effectiveness of AAA screening are recommended.

[Infrarenal abdominal aortic aneurysm: endovascular repair with stent grafts]

As an alternative to surgery, endovascular therapy with stent grafts has become the second main treatment option for infrarenal abdominal aortic aneurysms. Unlike surgery, endovascular treatment with stent grafts is also applicable in patients unfit for open repair. Despite current improvements in endovascular repair devices, significant anatomic barriers still exclude this technique for a large number of patients. Computed tomography, magnetic resonance imaging, and ultrasound are essential for diagnostics, preintervention planning, and postintervention follow-up of abdominal aneurysms treated with stent grafts. This review covers etiology, pathology, and diagnostic aspects. Materials and methods for endovascular treatment of abdominal aortic aneurysms are presented in detail, and clinical results and complications are discussed.

Screening for abdominal aortic aneurysms in men: a Canadian perspective using Monte Carlo-based estimates

OBJECTIVE

Recently generated randomized screening trial data have provided good evidence in favour of routine screening for abdominal aortic aneurysm (AAA) to reduce AAA-related deaths in men aged 65 years and older. We developed an economic model that assessed the incremental cost-utility of AAA screening to help decision makers judge the relevance of a national screening program in Canada.

METHODS

We constructed a 14 health state Markov model comparing 2 cohorts of 65-year-old men, where the first cohort was invited to attend screening for AAA using ultrasonography (US) and the second cohort followed the current practice of opportunistic detection. Lifetime outcomes included the life-years gained, AAA rupture avoided, AAA-related mortality, quality-adjusted life years (QALYs) and costs. Transition probabilities were derived from a systematic review of the literature, and a probabilistic sensitivity analysis was carried out to examine the effect of joint uncertainty in the variables of our analysis. The perspective adopted was that of the health care provider.

RESULTS

Invitations to attend screening produced an undiscounted gain in life expectancy of 0.049 years and a gain in discounted QALY of 0.019 for an estimated incremental lifetime cost of CAN$118. The estimated incremental cost-utility ratio was CAN$6194 per QALY gained (95% confidence interval [CI] 1892-10 837). The numbers needed to invite to attend screening, and the numbers needed to screen to prevent 1 AAA-related death were 187 (95% CI 130-292) and 137 (95% CI 85-213), respectively. The acceptability curve showed a greater than 95% probability of the program's being cost-effective, and the model was robust to changes in the values of key parameters within plausible ranges.

CONCLUSION

Our results support the economic viability of a national screening program for men reaching 65 years of age in Canada. More clinical studies are needed to define the role of screening in subgroups at high risk, especially in the female population.

Intracranial and abdominal aortic aneurysms: similarities, differences, and need for a new class of computational models

Intracranial saccular and abdominal aortic aneurysms (ISAs and AAAs, respectively) result from different underlying disease processes and exhibit different rupture potentials, yet they share many histopathological and biomechanical characteristics. Moreover, as in other vascular diseases, hemodynamics and wall mechanics play important roles in the natural history and possible treatment of these two types of lesions. The goals of this review are twofold: first, to contrast the biology and mechanics of intracranial and abdominal aortic aneurysms to emphasize that separate advances in our understanding of each disease can aid in our understanding of the other disease, and second, to suggest that research on the biomechanics of aneurysms must embrace a new paradigm for analysis. That is, past biomechanical studies have provided tremendous insight but have progressed along separate lines, focusing on either the hemodynamics or the wall mechanics. We submit that there is a pressing need to couple in a new way the separate advances in vascular biology, medical imaging, and computational biofluid and biosolid mechanics to understand better the mechanobiology, pathophysiology, and treatment of these lesions, which continue to be responsible for significant morbidity and mortality. We refer to this needed new class of computational tools as fluid-solid-growth (FSG) models.