Screening for abdominal aortic aneurysms in men

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.

Prospective Ultrasound Screening of Men With Cerebrovascular Disease for Abdominal Aortic Aneurysms

BACKGROUND

The prevalence of abdominal aortic aneurysms is higher in population with other vascular comorbidities, especially among men. Utility of screening among patients with cerebrovascular disease is unclear.

OBJECTIVE

To determine the prevalence of abdominal aortic aneurysm in male patients with diagnosed cerebrovascular disease manifested by transient ischemic attack or stroke.

METHODS

Between May 2013 and May 2014, all consecutive male patients undergoing carotid ultrasound in single tertiary center with a catchment area of 179,000 inhabitants were evaluated for ultrasound screening of abdominal aortic aneurysm. Abdominal aortic aneurysm was defined as maximum diameter of infrarenal aorta 30 mm or more.

RESULTS

Of 105 (n = 105) consecutively evaluated male patients, only 69% (n = 72) were eligible for the study and underwent aortic screening. Reason for ineligibility was most often poor general medical condition (n = 29). Mean age of screened patients was 66 years (SD 9.8 years). Half of the screened patients suffered stroke (n = 36). The incidence of abdominal aortic aneurysm was 5.6% (n = 4). All found abdominal aortic aneurysms were small and did not require immediate surgical intervention. During a follow-up period of over 4 years, none of the aneurysms exhibited tendency for growth.

CONCLUSIONS

The male population with cerebrovascular disease is comorbid and frail. Only, moderate prevalence of abdominal aortic aneurysms can be found in this subpopulation.

Screening Program of Abdominal Aortic Aneurysm

In Europe, the prevalence of abdominal aortic aneurysms (AAAs) in the elderly population (≥65 year old) has declined in the past decades to <4%. Aneurysmal degeneration of the aorta is a serious and potentially life-threatening vascular disease. Abdominal aortic aneurysms typically develop subclinically and often only become symptomatic when complicated by impending rupture. Most AAAs are discovered incidentally while investigating for an unrelated pathology. Ruptured AAA is the tenth leading cause of death in Belgium (0.32% of all deaths in 2014). Health-care providers have emphasized the importance of early detection of AAA and elective repair when the rupture risk outweighs operative risk (usual diameter threshold of 55 mm). Routine AAA screening programs, consisting of a single abdominal ultrasonography at the age of 65 years, aim to reduce the number of AAA-related deaths. Does population-based ultrasound screening for AAA achieve its objective and is it cost-effective? This literature review tries to answer these challenging questions.

Pathophisiology of abdominal aortic aneurysm: biomarkers and novel therapeutic targets

Abdominal aortic aneurysm (AAA) is a vascular pathology with a high rate of morbidity and mortality and a prevalence that, in men over 65 years, can reach around 8%. In this disease, usually asymptomatic, there is a progressive dilatation of the vascular wall that can lead to its rupture, a fatal phenomenon in more than 80% of cases. The treatment of patients with asymptomatic aneurysms is limited to periodic monitoring with imaging tests, control of cardiovascular risk factors and treatment with statins and antiplatelet therapy. There is no effective pharmacological treatment capable of limiting AAA progression or avoiding their rupture. At present, the aortic diameter is the only marker of risk of rupture and determines the need for surgical repair when it reaches values greater than 5.5cm. This review addresses the main aspects related to epidemiology, risk factors, diagnosis and clinical management of AAA, exposes the difficulties to have good biomarkers of this pathology and describes the strategies for the identification of new therapeutic targets and biomarkers in AAA.

Risk of abdominal aortic aneurysm (AAA) among male and female relatives of AAA patients

Sex affects the presentation, treatment, and outcomes of abdominal aortic aneurysm (AAA). Although AAAs are less prevalent in women, at least in the general population, women with an AAA have a poorer prognosis in comparison to men. Sex differences in the genetic predisposition for aneurysm disease remain to be established. In this study we investigated the familial risk of AAA for women compared to men. All living AAA patients included in a 2004-2012 prospective database were invited to the multidisciplinary vascular/genetics outpatient clinic between 2009 and 2012 for assessment of family history using detailed questionnaires. AAA risk for male and female relatives was calculated separately and stratified by sex of the AAA patients. Families of 568 AAA patients were investigated and 22.5% of the patients had at least one affected relative. Female relatives had a 2.8-fold and male relatives had a 1.7-fold higher risk than the estimated sex-specific population risk. Relatives of female AAA patients had a higher aneurysm risk than relatives of male patients (9.0 vs 5.9%, p = 0.022), corresponding to 5.5- and 2.0-fold increases in aneurysm risk in the female and male relatives, respectively. The risk for aortic aneurysm in relatives of AAA patients is higher than expected from population risk. The excess risk is highest for the female relatives of AAA patients and for the relatives of female AAA patients. These findings endorse targeted AAA family screening for female and male relatives of all AAA patients.

Transperitoneal versus retroperitoneal approach for elective open abdominal aortic aneurysm repair

BACKGROUND

There has been extensive debate in the surgical literature regarding the optimum surgical access approach to the infrarenal abdominal aorta during an operation to repair an abdominal aortic aneurysm. The published trials comparing retroperitoneal (RP) and transperitoneal (TP) aortic surgery show conflicting results.

OBJECTIVES

To assess the effectiveness and safety of the transperitoneal versus retroperitoneal approach for elective open abdominal aortic aneurysm repair on mortality, complications, hospital stay and blood loss.

SEARCH METHODS

The Cochrane Vascular Trials Search Co-ordinator searched the Cochrane Vascular Specialised Register (last searched May 2015) and CENTRAL (2015, Issue 4) and trials databases (May 2015). The review authors searched the Chinese Biomedical Literature Database and other resources including clinical trials registers.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that assessed the TP approach versus the RP approach for elective open abdominal aortic aneurysm (AAA) repair. We evaluated the outcomes of mortality, complications, intensive care unit (ICU) stay, hospital stay, blood loss, aortic cross-clamp time and operating time. Two review authors independently selected RCTs against the inclusion criteria. We resolved any disagreements by discussion with a third review author.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data from the included trials. We resolved any disagreements by discussion with a third review author. Two review authors independently assessed the risk of bias according to a standard quality checklist provided by Cochrane Vascular.

MAIN RESULTS

We included four RCTs, with a combined total of 129 participants, that assessed the TP approach versus the RP approach for elective open AAA repair. The overall quality of the evidence was low to very low because of the low methodological quality of the included trials (unclear random sequence generation method and allocation concealment, and no blinding of outcome assessors), small sample sizes, small number of events, high heterogeneity and inconsistency between the included trials, no power calculations and relatively short follow-up. There were no differences between the RP approach and the TP approach regarding mortality (odds ratio (OR) 0.32, 95% CI 0.01 to 8.25; 110 participants; four trials; P = 0.49; I² statistic = 0%; very low quality evidence). However, the RP approach may increase complications, such as hematoma (OR 0.90, 95% CI 0.13 to 6.48; 75 participants; two trials; P = 0.92; very low quality evidence), chronic wound pain (OR 2.20, 95% CI 0.36 to 13.34; 48 participants; one trial; P = 0.39; very low quality evidence) and abdominal wall hernia (OR 10.76, 95% CI 0.55 to 211.78; 48 participants; one trial; P = 0.12; very low quality evidence) compared with the TP approach in the patients for elective open AAA repair, but the confidence intervals (CIs) were wide. The RP approach reduced the blood loss (mean difference (MD) -504.87 mL, 95% CI -779.19 to -230.56; 129 participants; four trials; P = 0.003; very low quality evidence), ICU stay (MD -19.00 hours, 95% CI -31.41 to -6.59; 83 participants; two trials; P = 0.003; low quality evidence) and hospital stay (MD -3.14 days, 95% CI -4.82 to -1.45; 129 participants; four trials; P = 0.0003; low quality evidence). There were no differences between the RP approach and the TP approach regarding aortic cross-clamp time (MD 0.69 mins, 95% CI -7.23 to 8.60; 129 participants; four trials; P = 0.86; very low quality evidence) and operating time (MD -15.94 mins, 95% CI -34.76 to 2.88; 129 participants; four trials; P = 0.10; very low quality evidence).

AUTHORS' CONCLUSIONS

Very low quality evidence from four small RCTs indicates that the RP approach did not have advantages over the TP approach for elective open AAA repair in terms of mortality. Moreover, the RP approach may increase the risk of postoperative wound complications although the CIs were wide.Low quality evidence shows that the RP approach could reduce blood loss, hospital stay and ICU stay compared with the TP approach. Very low quality evidence shows no differences between the RP approach and TP approaches in aortic cross-clamp time and operating time.Further large-scale RCTs of the RP approach versus TP approach for elective open AAA repair are required.

Abdominal aortic aneurysm screening for high-risk cardiac patients in the emergency department

Background: The prevalence of abdominal aortic aneurysm (AAA) is 1-2 percent in the general population, and is as high as 6 percent in groups with risk factors. Objectives: The aim of this study was to determine the prevalence of AAA amongst high-risk cardiac patients in the emergency department (ED). Methods: A prospective study was conducted to evaluate the prevalence of AAA in a high-risk population presenting to the ED. Inclusion criteria included male gender, Caucasian race, age over 50 years, history of smoking, and presentation to the ED with chest pain requiring admission. Patients enrolled in the study were screened for AAA by ultrasound (US) scan. Study subjects were excluded if there was inadequate imaging. Results: One hundred and nine patients were recruited into the study. Nineteen patients were excluded by the ED US Director secondary to inadequate imaging. Of the remaining 90 patients, eight patients were found to have AAA (n = 8; 8.9%; CI 3.9 - 16.8%). Of the eight patients with an AAA, four had diagnosed cardiovascular disease during their hospital admission. There was no statistically significant difference in secondary risk factors such as hypertension, diabetes, dyslipidemia or previous history of coronary artery disease between those with AAA and those without AAA. Conclusions: This study found that in a single ED, the prevalence of AAA in high-risk cardiac patients admitted to rule out acute coronary syndrome who could be adequately visualized with ultrasound was over 8 percent. With such a high prevalence, this population could be a potential screening group.

Early prediction of survival after open surgical repair of ruptured abdominal aortic aneurysms

Background

Scoring models are widely established in the intensive care unit (ICU). However, the importance in patients with ruptured abdominal aortic aneurysm (RAAA) remains unclear. Our aim was to analyze scoring systems as predictors of survival in patients undergoing open surgical repair (OSR) for RAAA.

Methods

This is a retrospective study in critically ill patients in a surgical ICU at a university hospital. Sixty-eight patients with RAAA were treated between February 2005 and June 2013. Serial measurements of Sequential Organ Failure Assessment score (SOFA), Simplified Acute Physiology Score II (SAPS II) and Simplified Therapeutic Intervention Scoring System-28 (TISS-28) were evaluated with respect to in-hospital mortality. Eleven patients had to be excluded from this study because 6 underwent endovascular repair and 5 died before they could be admitted to the ICU.

Results

All patients underwent OSR. The initial, highest, and mean of SOFA and SAPS II scores correlated significant with in-hospital mortality. In contrast, TISS-28 was inferior and showed a smaller area under the receiver operating curve. The cut-off point for SOFA showed the best performance in terms of sensitivity and specificity. An initial SOFA score below 9 predicted an in-hospital mortality of 16.2% (95% CI, 4.3–28.1) and a score above 9 predicted an in-hospital mortality of 73.7% (95% CI, 53.8–93.5, p < 0.01). Trend analysis showed the largest effect on SAPS II. When the score increased or was unchanged within the first 48 h (score >45), the in-hospital mortality rate was 85.7% (95% CI, 67.4–100, p < 0.01) versus 31.6% (95% CI, 10.7–52.5, p = 0.01) when it decreased. On multiple regression analysis, only the mean of the SOFA score showed a significant predictive capacity with regards to mortality (odds ratio 1.77; 95% CI, 1.19–2.64; p < 0.01).

Conclusion

SOFA and SAPS II scores were able to predict in-hospital mortality in RAAA within 48 h after OSR. According to cut-off points, an increase or decrease in SOFA and SAPS II scores improved sensitivity and specificity.

Abdominal aortic aneurysm in patients affected by intermittent claudication: prevalence and clinical predictors

Background

Abdominal aortic aneurysm (AAA) is a frequent cause of death among elderly. Patients affected by lower extremity peripheral arterial disease (LE-PAD) seem to be particularly at high risk for AAA. We aimed this study at assessing the prevalence and the clinical predictors of the presence of AAA in a homogeneous cohort of LE-PAD patients affected by intermittent claudication.

Methods

We performed an abdominal ultrasound in 213 consecutive patients with documented LE-PAD (ankle/brachial index ≤0.90) attending our outpatient clinic for intermittent claudication. For each patient we registered cardiovascular risk factors and comorbidities, and measured neutrophil count.

Results

The ultrasound was inconclusive in 3 patients (1.4%), thus 210 patients (169 males, 41 females, mean age 65.9 ± 9.8 yr) entered the study. Overall, AAA was present in 19 patients (9.0%), with a not significant higher prevalence in men than in women (10.1% vs 4.9%, p = 0.300). Patients with AAA were older (71.2 ± 7.0 vs 65.4 ± 9.9 years, p = 0.015), were more likely to have hypertension (94.7% vs 71.2%, p = 0.027), and greater neutrophil count (5.5 [4.5 – 6.2] vs 4.1 [3.2 – 5.5] x10³/μL, p = 0.010). Importantly, the c-statistic for neutrophil count (0.73, 95% CI 0.60 – 0.86, p =0.010) was higher than that for age (0.67, CI 0.56–0.78, p = 0.017). The prevalence of AAA in claudicant patients with a neutrophil count ≥ 5.1 x10³/μL (cut-off identified at ROC analysis) was as high as 29.0%.

Conclusions

Prevalence of AAA in claudicant patients is much higher than that reported in the general population. Ultrasound screening should be considered in these patients, especially in those with an elevated neutrophil count.

Aragon workers' health study--design and cohort description

Background

Spain, a Mediterranean country with relatively low rates of coronary heart disease, has a high prevalence of traditional cardiovascular risk factors and is experiencing a severe epidemic of overweight/obesity. We designed the Aragon Workers’ Health Study (AWHS) to characterize the factors associated with metabolic abnormalities and subclinical atherosclerosis in a middle aged population in Spain free of clinical cardiovascular disease. The objective of this paper is to describe the study design, aims and baseline characteristics of participants in the AWHS.

Methods/Design

Longitudinal cohort study based on the annual health exams of 5,400 workers of a car assembly plant in Figueruelas (Zaragoza, Spain). Study participants were recruited during a standardized clinical exam in 2009–2010 (participation rate 95.6%). Study participants will undergo annual clinical exams and laboratory assays, and baseline and triennial collection of biological materials for biobanking and cardiovascular imaging exams (carotid, femoral and abdominal ultrasonography, coronary calcium score, and ankle-arm blood pressure index). Participants will be followed-up for 10 years.

Results

The average (SD) age, body mass index, and waist circumference were 49.3 (8.7) years, 27.7 (3.6) kg/m² and 97.2 (9.9) cm, respectively, among males (N = 5,048), and 40.8 (11.6) years, 24.4 (3.8) kg/m², and 81.9 (9.9) cm, among females (N = 351). The prevalence of overweight, obesity, current smoking, hypertension, hypercholesterolemia, and diabetes were 55.0, 23.1, 37.1, 40.3, 75.0, and 7.4%, respectively, among males, and 23.7, 8.3, 45.0, 12.1, 59.5, and 0.6%, respectively, among females. In the initial 587 study participants who completed all imaging exams (94.5% male), the prevalence of carotid plaque, femoral plaque, coronary calcium score >1 to 100, and coronary calcium score >100 was 30.3, 56.9, 27.0, and 8.8%, respectively. 67.7% of study participants had at least one plaque in the carotid or femoral arteries.

Discussion

Baseline data from the AWHS show a high prevalence of cardiovascular risk factors and of sublinical atherosclerosis. Follow-up of this cohort will allow the assessment of subclinical atherosclerosis progression and the link of disease progression to traditional and emergent risk factors.

A simulation framework for estimating wall stress distribution of abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) rupture is believed to occur when the mechanical stress acting on the wall exceeds the strength of the wall tissue. In endovascular aneurysm repair, a stent-graft in a catheter is released at the aneurysm site to form a new blood vessel and protect the weakened AAA wall from the pulsatile pressure and, hence, possible rupture. In this paper, we propose a framework to estimate the wall stress distribution of non-stented/stented AAA based on fluid-structure interaction, which is utilized in a surgical simulation system (IRAS). The 3D geometric model of AAA is reconstructed from computed tomography angiographic (CTA) images. Based on our experiments, a combined logarithm and polynomial strain energy equation is applied to model the elastic properties of arterial wall. The blood flow is modeled as laminar, incompressible, and non-Newtonian flow by applying Navier-Stokes equation. The obtained pressure of blood flow is applied as load on the AAA meshes with and without stent-graft and the wall stress distribution is calculated by fluid-structure interaction (FSI) solver equipped in ANSYS. Experiments demonstrate that our analytical results are consistent with clinical observations.

Pathophysiology and epidemiology of abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) are found in up to 8% of men aged >65 years, yet usually remain asymptomatic until they rupture. Rupture of an AAA and its associated catastrophic physiological insult carries overall mortality in excess of 80%, and 2% of all deaths are AAA-related. Pathologically, AAAs are associated with inflammation, smooth muscle cell apoptosis, and matrix degradation. Once thought to be a consequence of advanced atherosclerosis, accruing evidence indicates that AAAs are a focal representation of a systemic disease of the vasculature. Risk factors for AAAs include increasing age, male sex, smoking, and low HDL-cholesterol levels. Familial associations exist and although susceptibility genes have been described on the basis of candidate-gene studies, robust genetic studies have failed to discover causative gene mutations. The surgical management of AAAs has been revolutionized by minimally invasive endovascular repair. Ongoing randomized trials will establish whether endovascular repair confers a survival advantage over open surgery for patients with a ruptured AAA. In many countries, centralization of vascular surgical services has largely been driven by the improved outcomes of elective aneurysm surgery in specialized centers, the widespread adoption of endovascular techniques, and the introduction of screening programs.

Ultrasound imaging in the National Health Service Abdominal Aortic Aneurysm Screening Programme

A screening programme for abdominal aortic aneurysm commenced in England in April 2009. Once rolled out across the country, it is estimated that up to 50% of deaths from ruptured aortic aneurysm will be prevented. Ultrasound imaging of the aorta is the screening test at the core of the programme. Screening will be done by technicians who have had specific training in imaging the aorta. A training programme is being organized that accredits technicians to national standards. There will be a quality assurance programme that will underpin the screening service, analysing both technicians and ultrasound machines. Also, there will be continuing professional development for the technicians to allow them career progression. Finally, the size of the programme will be an incentive for ultrasound machine manufacturers to produce dedicated equipment.

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.

Abdominal aortic aneurysm--to screen or not to screen

With the ten WHO criteria for a screening program to be started, screening for abdominal aortic aneurysm is analyzed. Most of the criteria are fulfilled concerning the 65-year old male population, whereas concerning females we need more knowledge. Still the aneurysmal diameter is the most important factor to select patients for treatment meaning that many aneurysms are treated where rupture should never have occurred. Research projects giving more information on pathophysiological processes behind expansion and rupture should have priority.

Screening for popliteal aneurysms should not be a routine part of a community-based aneurysm screening program

Introduction

Several studies have found an increased incidence of peripheral aneurysms in patients with an abdominal aortic aneurysm (AAA). The aim of this study was to determine whether screening for popliteal aneurysms should be part of an AAA screening programme.

Setting

A community-based AAA screening programme

Methods

The diameters of the internal abdominal aorta and both popliteal arteries were assessed by B-Mode ultrasound in a subgroup of the screened population. An AAA was defined as an infrarenal aortic diameter >29 mm. A popliteal aneurysm was defined as a popliteal diameter >19 mm.

Results

Information was available for 283 subjects, 112 subjects with a small AAA, and 171 subjects with a normal aorta. No popliteal aneurysms were found in the subjects with a normal aorta. Three popliteal aneurysms were found in patients with a small AAA. Scanning both popliteal arteries took an experienced sonographer on average three times as long as scanning for an AAA (5 vs 15 minutes).

Conclusion

Popliteal artery aneurysms are seen in less than 3% of men with a small AAA and not at all in men with a normal aortic diameter. It is therefore not cost effective to include screening for popliteal aneurysms in population screening for AAA.

Informing the efficient use of health care and health care research resources - the case of screening for abdominal aortic aneurysm in Sweden

BACKGROUND

An analytical framework using Bayesian decision theory and value-of-information analysis has recently been advocated for the economic evaluation of health technologies. The purpose of this study was to apply this framework to screening for abdominal aortic aneurysm (AAA) in Sweden and to compare the conclusions from this study with the conclusions presented in an assessment performed by the Swedish Council of Technology Assessment (SBU).

METHODS

A probabilistic decision-analytical model was developed to establish the cost-effectiveness of a screening programme for AAA relative to current clinical practice and to calculate the value-of-information.

RESULTS

The cost per quality-adjusted life-year for screening was 9700 euro. The expected value of perfect information for the assessment of overall cost-effectiveness was low, suggesting little benefit in conducting further research. Expected value of perfect partial information indicated that rupture probabilities were associated with the highest uncertainty. By contrast, the SBU report concluded there was limited evidence of cost-effectiveness and proposed further research.

CONCLUSION

The investigated screening programme for AAA is likely to be cost-effective and conducting another clinical trial is unlikely to add much valuable information to this decision problem. These recommendations contrast with the vaguer recommendations from SBU that more evidence is required of costs-effectiveness.

Concomitant Detection of Systemic Atherosclerotic Disease while Screening for Abdominal Aortic Aneurysm

INTRODUCTION

Although population screening for abdominal aortic aneurysm (AAA) has/had a significant impact on disease-specific mortality, coexisting systemic atherosclerosis represents the major impediment to improved longevity. We examined the feasibility and yield of full cardiovascular assessment concomitant with screening for AAA detection.

METHODS

A total of 1032 asymptomatic men over the age of 50 years (328 were >60 years) underwent a detailed cardiac health questionnaire, sphygmomanometry, body mass index calculation, fasting lipid profiling, ultrasonographic (US) examination of their infrarenal aorta and carotid arteries, and treadmill exercise stress testing. Framingham and SCORE project estimations of the 10-year risk of ischemic heart disease (IHD) and fatal cardiovascular disease (CVD) of any cause were calculated for the men with an AAA and in those>60 years but with neither AAA nor known cardiac disease.

RESULTS

Overall, we detected an AAA>3 cm in 30 men (2.9%). Unaddressed obesity, smoking, hypertension, impaired glucose metabolism, and hypercholesterolemia were commonly identified in individuals both with and without an AAA, being notably frequent in those>60 years without an AAA. The 10-year risk of IHD and CHD in those>60 years was similar regardless of whether an AAA was present. Doppler screening for significant carotid stenosis had detection rates similar to those for aortic US scanning, being most useful in those>65 years of age. Exercise stress testing, however, was of only limited value when used nonselectively.

CONCLUSIONS

Modifiable atherosclerotic disease and cardiovascular risk can be readily detected in individuals presenting for AAA screening and are present to a significant degree at an earlier age. Consideration of selected, additional investigations is required to maximize the value of generalized screening programs.

Community-based, nonprofit organization-sponsored ultrasonography screening program for abdominal aortic aneurysms is effective at identifying occult aneurysms

Early diagnosis of abdominal aortic aneurysm (AAA), prior to rupture, is vital for optimizing patient survival. An abdominal ultrasonography examination of an asymptomatic individual to check for the presence of an AAA, however, is not presently reimbursed by health insurance in the United States. This article reports the results of one nonprofit, community-based screening program, run by Aneurysm Outreach, Inc. (AOI; www.alink.org). AOI offered free screening for AAA to anyone who met the criteria of being (1) over 60 years old; (2) over 50 years old, male, and with positive family history for AAA; or (3) over 55 years old, female, and with positive family history for AAA. AOI organized 21 ultrasonographic screening events between September 2001 and November 2004, and the number of participants per event varied from 24 to 240. Altogether 3,088 individuals met the screening criteria and 22 of them were already known to have AAAs. Thirty-six (1.2%) individuals were excluded from the final analysis due to poor quality of the ultrasonographic images. Among the remaining 3,030 individuals, a dilatation of the aorta was detected and confirmed in 61 (2.0%) individuals, in 4.3% of the screened males and in 0.6% of the screened females. Thirteen individuals had their AAAs repaired surgically. The frequencies of males and current smokers were significantly higher in the AAA group than in the group with normal-size aorta (male AAA 83.6% vs. normal 42.0%, p < 0.0001; smoker AAA 54.9% vs. normal 18.1%, p < 0.0001). The mean age was significantly higher in the AAA group than in the group with normal-size aorta (AAA 71.0 +/- 6.2 vs. normal 68.4 +/- 7.0, p = 0.005). In conclusion, the results of this community-based free ultrasonographic screening program are in agreement with randomized controlled screening programs and emphasize the need for systematic screening programs and the importance of finding individuals harboring AAAs before their rupture.

The lifetime prevalence of abdominal aortic aneurysms among siblings of aneurysm patients is eightfold higher than among siblings of spouses: an analysis of 187 aneurysm families in Nova Scotia, Canada

BACKGROUND

Abdominal aortic aneurysms (AAAs) are frequently familial. The aim of this study was to compare the prevalence of AAA among the siblings of AAA patients with that in the spouses' siblings.

METHODS

The siblings of 375 AAA patients and the siblings of the spouses of the AAA patients were included in this study and offered ultrasonography screening for AAA. Participants were asked to complete a questionnaire to collect demographic and general health information. Statistical analysis was done with Fisher's exact test. Odds ratios and 95% confidence intervals were also calculated.

RESULTS

Abdominal ultrasonography examinations were done for 309 individuals. The results indicated that 11 (11.2%) of 98 brothers of AAA patients, 4 (2.7%) of 147 sisters, and none of the 64 siblings of the spouses of the AAA patients were found to have an AAA. Combining the information from the ultrasonography screening and medical records on already known cases of AAA in these families, altogether 29.0% (44/152) of the brothers of AAA patients, 11.1% (20/181) of the sisters of AAA patients, and 2.3% (2/88) of the siblings of the spouses had an AAA.

CONCLUSION

There was a significant difference between the siblings of the AAA patients and those of the spouses both in the frequency of AAA detected by ultrasonography screening and in the overall prevalence of AAA. The overall prevalence of AAA in the siblings of AAA patients was about eight times that observed among the siblings of their spouses (19.2% vs 2.3%). These findings confirmed previous reports on high prevalence of AAA among siblings of AAA patients and emphasized the importance of an ultrasonography screening program for siblings of AAA patients.

Trends in mortality and hospital admission rates for abdominal aortic aneurysm in England and Wales, 1979-1999

BACKGROUND

The aim of this study was to investigate trends in population-based mortality, hospital admission and case fatality rates for abdominal aortic aneurysm (AAA) from 1979 to 1999.

METHODS

This was an analysis of routine statistics from 79 495 death certificates in England and Wales and 3217 hospital inpatient admissions in the Oxford Region.

RESULTS

Mortality rates for all AAAs increased between 1979 and 1999 from 13 to 25 per million in women and from 80 to 115 per million in men. Admission rates increased in the same time interval from three to 22 admissions per million per year in women, and from 52 to 149 per million per year in men. Case fatality rates for all non-ruptured AAAs that were operated on decreased from 25.8 to 9.0 per cent and for all ruptured AAAs from 69.9 to 54.4 per cent.

CONCLUSION

Mortality rates and hospital admission rates for AAA rose in men and even more so in women between 1979 and 1999. Perioperative mortality for ruptured AAA declined a little during the study but nonetheless was still very high at the end. This reinforces the importance of detecting and treating AAA before rupture occurs.

Decision-analytical model with lifetime estimation of costs and health outcomes for one-time screening for abdominal aortic aneurysm in 65-year-old men

Background

Abdominal aortic aneurysm (AAA) causes about 2 per cent of all deaths in men over the age of 65 years. A major improvement in operative mortality would have little impact on total mortality, so screening for AAA has been recommended as a solution. The cost-effectiveness of a programme that invited 65-year-old men for ultrasonographic screening was compared with current clinical practice in a decision-analytical model.

Methods

In a probabilistic Markov model, costs and health outcomes of a screening programme and current clinical practice were simulated over a lifetime perspective. To populate the model with the best available evidence, data from published papers, vascular databases and primary research were used.

Results

The results of the base-case analysis showed that the incremental cost per gained life-year for a screening programme compared with current practice was €7760, and that for a quality-adjusted life-year was €9700. The probability of screening being cost-effective was high.

Conclusion

A financially and practically feasible screening programme for AAA, in which men are invited for ultrasonography in the year in which they turn 65, appears to yield positive health outcomes at a reasonable cost.

Implications of screening for abdominal aortic aneurysms on surgical workload

Background

The Multicentre Aneurysm Screening Study (MASS) provided strong evidence for both the clinical benefit and the cost-effectiveness of a screening programme for abdominal aortic aneurysms (AAAs) in men. If a national screening programme for AAA were adopted in the UK, it would be expected to increase the elective and decrease the emergency surgical workload.

Methods

The MASS trial randomized 67 800 men aged 65–74 years to be invited to attend for ultrasonographic screening for AAA or to a control group that received no invitation. Predictions of elective and emergency surgical workload were made for a 20-year interval after the introduction of a screening programme for 65-year-old men, based on surgical rates observed in the MASS trial and national mortality statistics.

Results

For a district general hospital serving a population of 400 000, there was an estimated reduction from nine emergency operations per year before introduction of the screening programme to three emergency operations annually in men aged 65 years and over by the end of the 20-year interval, and an increase from 24 to 43 AAA operations overall. The corresponding estimated annual costs for all AAA surgery increased by 47 per cent, from £209 000 to £308 000. These results were not affected by changes in the underlying assumptions.

Conclusion

The results support the expectation of very few emergency operations, and principally elective operations, being performed following the introduction of a screening programme. For a typical district general hospital, a screening programme would be expected to lead to two additional elective AAA operations per month, and to save 11 AAA-related deaths per year.

Late Survival after Elective Repair of Aortic Aneurysms Detected by Screening

BACKGROUND

The aim of this study was to examine whether there was any survival advantage in men following elective repair of an abdominal aortic aneurysm (AAA) detected by ultrasound screening compared to those with an AAA detected incidentally.

METHODS

A total of 424 men underwent elective AAA repair between 1990 and 1998; 181 were detected in an aneurysm screening programme and 243 were diagnosed incidentally. Follow-up survival data were collected until 2003 (minimum 5 years) and survival curves were compared using regression analysis.

RESULTS

The postoperative 30-day mortality rate was significantly lower in men whose aneurysms were detected by screening (4.4%), compared with those detected incidentally (9.0%). Similarly, 5-year survival (78% vs. 65%) and 10-year survival rates (63% vs. 40%) were better after repair of a screen-detected AAA (p<0.0003 at all time intervals, by log rank testing). Multivariate analysis showed that this was largely due to the older age of men who had repair of an incidental AAA (71.2 vs. 67.1 years).

CONCLUSION

Men who had elective repair of an AAA detected by screening had a better late survival rate than men whose aneurysm was discovered incidentally because they were younger at the time of surgery.