Fifteen-year follow-up of a randomized clinical trial of ultrasonographic screening for abdominal aortic aneurysms

Abdominal Aortic Aneurysm: Evolving Controversies and Uncertainties

Abdominal aortic aneurysm (AAA) is defined as a permanent dilatation of the abdominal aorta that exceeds 3 cm. Most AAAs arise in the portion of abdominal aorta distal to the renal arteries and are defined as infrarenal. Most AAAs are totally asymptomatic until catastrophic rupture. The strongest predictor of AAA rupture is the diameter. Surgery is indicated to prevent rupture when the risk of rupture exceeds the risk of surgery. In this review, we aim to analyze this disease comprehensively, starting from an epidemiological perspective, exploring etiology and pathophysiology, and concluding with surgical controversies. We will pursue these goals by addressing eight specific questions regarding AAA: (1) Is the incidence of AAA increasing? (2) Are ultrasound screening programs for AAA effective? (3) What causes AAA: Genes versus environment? (4) Animal models: Are they really relevant? (5) What pathophysiology leads to AAA? (6) Indications for AAA surgery: Are surgeons over-eager to operate? (7) Elective AAA repair: Open or endovascular? (8) Emergency AAA repair: Open or endovascular?

Ultrasound screening for abdominal aortic aneurysm: current practice, challenges and controversies

The UK screening programme began in 2009, and has now been expanded around the UK. Long-term follow-up of the original cohorts continues to demonstrate significant benefits for abdominal aortic aneurysm (AAA)-related and all-cause mortality , and results from the first 5 years of the formal screening programme have demonstrated similar success. Ultrasound scanning is an effective and safe screening tool for the detection of AAA, although a variety of measurement protocols are employed internationally. Key challenges for the future of the programme relate to declining incidence of screen detected aneurysms.  Recent publications have demonstrated a UK incidence of only 1.34%, compared to 4.9-7.2% of men invited for screening in the original trials. Work into increasing engagement amongst the target group, and expanding screening to siblings and women is underway to address this issue. This review describes the evidence behind the screening programme, its justification in addressing AAA as a significant health problem and discusses some of the potential developments in the future.

AGD: Aneurysm Gene Database

An aneurysm is an outward bulge on an arterial wall. Aneurysms are becoming a serious public health concern as the worldwide population ages. Unfortunately, no effective drugs have been developed for aneurysms to date. In addition, aneurysms may be associated with grave prognosis due to conditions such as ruptures and recurrence. Altogether, these factors make earlier aneurysm prevention, diagnosis and intervention strategies even more important. A bioinformatics resource for aneurysm-associated molecules would be helpful for addressing the above issues; however, such a tool is not yet available. In this study, we developed Aneurysm Gene Database (AGD) for the above purpose. AGD contains 1472 aneurysm-gene associations, including 29 types of aneurysms, 967 protein-coding genes, 29 miRNAs, 6 lncRNAs and several other types of molecules. Users can search, browse and download content in AGD. We believe that AGD is a valuable resource that can help us better understand aneurysms and discover novel treatment targets.

The UK EndoVascular Aneurysm Repair (EVAR) randomised controlled trials: long-term follow-up and cost-effectiveness analysis

BACKGROUND

Short-term survival benefits of endovascular aneurysm repair (EVAR) compared with open repair (OR) of intact abdominal aortic aneurysms have been shown in randomised trials, but this early survival benefit is soon lost. Survival benefit of EVAR was unclear at follow-up to 10 years.

OBJECTIVE

To assess the long-term efficacy of EVAR against OR in patients deemed fit and suitable for both procedures (EVAR trial 1; EVAR-1); and against no intervention in patients unfit for OR (EVAR trial 2; EVAR-2). To appraise the long-term significance of type II endoleak and define criteria for intervention.

DESIGN

Two national, multicentre randomised controlled trials: EVAR-1 and EVAR-2.

SETTING

Patients were recruited from 37 hospitals in the UK between 1 September 1999 and 31 August 2004.

PARTICIPANTS

Men and women aged ≥ 60 years with an aneurysm of ≥ 5.5 cm (as identified by computed tomography scanning), anatomically suitable and fit for OR were randomly assigned 1 : 1 to either EVAR (n = 626) or OR (n = 626) in EVAR-1 using computer-generated sequences at the trial hub. Patients considered unfit were randomly assigned to EVAR (n = 197) or no intervention (n = 207) in EVAR-2. There was no blinding.

INTERVENTIONS

EVAR, OR or no intervention.

MAIN OUTCOME MEASURES

The primary end points were total and aneurysm-related mortality until mid-2015 for both trials. Secondary outcomes for EVAR-1 were reinterventions, costs and cost-effectiveness.

RESULTS

In EVAR-1, over a mean of 12.7 years (standard deviation 1.5 years; maximum 15.8 years), we recorded 9.3 deaths per 100 person-years in the EVAR group and 8.9 deaths per 100 person-years in the OR group [adjusted hazard ratio (HR) 1.11, 95% confidence interval (CI) 0.97 to 1.27; p = 0.14]. At 0-6 months after randomisation, patients in the EVAR group had a lower mortality (adjusted HR 0.61, 95% CI 0.37 to 1.02 for total mortality; HR 0.47, 95% CI 0.23 to 0.93 for aneurysm-related mortality; p = 0.031), but beyond 8 years of follow-up patients in the OR group had a significantly lower mortality (adjusted HR 1.25, 95% CI 1.00 to 1.56, p = 0.048 for total mortality; HR 5.82, 95% CI 1.64 to 20.65, p = 0.0064 for aneurysm-related mortality). The increased aneurysm-related mortality in the EVAR group after 8 years was mainly attributable to secondary aneurysm sac rupture, with increased cancer mortality also observed in the EVAR group. Overall, aneurysm reintervention rates were higher in the EVAR group than in the OR group, 4.1 and 1.7 per 100 person-years, respectively (p < 0.001), with reinterventions occurring throughout follow-up. The mean difference in costs over 14 years was £3798 (95% CI £2338 to £5258). Economic modelling based on the outcomes of the EVAR-1 trial showed that the cost per quality-adjusted life-year gained over the patient's lifetime exceeds conventional thresholds used in the UK. In EVAR-2, patients died at the same rate in both groups, but there was suggestion of lower aneurysm mortality in those who actually underwent EVAR. Type II endoleak itself is not associated with a higher rate of mortality.

LIMITATIONS

Devices used were implanted between 1999 and 2004. Newer devices might have better results. Later follow-up imaging declined, particularly for OR patients. Methodology to capture reinterventions changed mainly to record linkage through the Hospital Episode Statistics administrative data set from 2009.

CONCLUSIONS

EVAR has an early survival benefit but an inferior late survival benefit compared with OR, which needs to be addressed by lifelong surveillance of EVAR and reintervention if necessary. EVAR does not prolong life in patients unfit for OR. Type II endoleak alone is relatively benign.

FUTURE WORK

To find easier ways to monitor sac expansion to trigger timely reintervention.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN55703451.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and the results will be published in full in Health Technology Assessment; Vol. 22, No. 5. See the NIHR Journals Library website for further project information.

Aortic Aneurysm as a Complication of Myeloperoxidase-antineutrophil Cytoplasmic Antibody-associated Vasculitis

Myeloperoxidase-antineutrophil cytoplasmic antibody-associated vasculitis (MPO-AAV) does not usually involve large vessels, such as the aorta. However, we experienced three cases having an aortic aneurysm as a complication of MPO-AAV with renal insufficiency. In one patient it involved the onset of descending aortic dissection during treatment for MPO-AAV; another two patients had an abdominal aortic aneurysm at the time of our diagnosis of MPO-AAV. Although we found no pathological evidence in our patients, MPO-AAV might result in large vessel inflammation. Therefore, we suggest that patients with MPO-AAV should be examined by computed tomography scan to check for the presence of an aortic aneurysm.

Unusual presentation of silently growing abdominal aortic aneurysm causing biliary obstruction

Biliary obstruction is a rare presentation of abdominal aortic aneurysm (AAA). The most common symptoms of AAA are abdominal or back pain and limb ischaemia from thromboembolism. We report a case of a 67-year-old male who was diagnosed with obstructive jaundice secondary to an AAA. CT angiogram revealed compression of the common bile duct by the large AAA, causing diffuse intrahepatic and extrahepatic ductal dilatation. Surgical repair of the aortic aneurysm was successful, and patient's symptoms improved.

Investigation of reference levels and radiation dose associated with abdominal EVAR (endovascular aneurysm repair) procedures across several European Centres

OBJECTIVES

Endovascular aneurysm repair (EVAR) is considered the treatment of choice for abdominal aortic aneurysms with suitable anatomy. In order to improve radiation safety, European Directive (2013/59) requires member states to implement diagnostic reference levels (DRLs) in radio-diagnostic and interventional procedures. This study aimed to determine local DRLs for EVAR across five European centres and identify an interim European DRL, which currently remains unestablished.

METHODS

Retrospective data was collected for 180 standard EVARs performed between January 2014 and July 2015 from five specialist centres in Ireland (n=2) and Italy (n=3). Data capture included: air kerma-area product (P_KA), total air kerma at the reference point (K_a,r), fluoroscopic time (FT), number of acquisitions, frame rate of acquisition, type of acquisition, patient height, weight, and gender.

RESULTS

The mean values for each site A, B, C, D, and E were: P_KAs of 4343 ± 994 μGym², 18,200 ± 2141 μGym², 11,423 ± 1390 μGym², 7796 ± 704 μGym², 31,897 ± 5798 μGym²; FTs of 816 ± 92 s, 950 ± 150 s, 708 ± 70 s, 972 ± 61 s, 827 ± 118 s; and number of acquisitions of 6.72 ± 0.56, 10.38 ± 1.54, 4.74 ± 0.19, 5.64 ± 0.36, 7.28 ± 0.65, respectively. The overall pooled 75th percentile P_KA was 15,849 μGym².

CONCLUSION

Local reference levels were identified. The pooled data has been used to establish an interim European DRL for EVAR procedures.

KEY POINTS

• Abdominal endovascular aneurysm repair (EVAR) requires the use of ionising radiation. • EVAR is a minimally invasive procedure for the treatment of abdominal aortic aneurysms. • Diagnostic reference levels (DRLs) are used to monitor patient radiation exposure. • Radiation dose data was collected from five European centres for EVAR procedures. • Local DRLs have been determined and an interim European DRL is proposed.

Screening for abdominal aortic aneurysm in asymptomatic adults

BACKGROUND

This report was produced for the Canadian Task Force on Preventive Health Care to provide guidelines on screening for abdominal aortic aneurysm (AAA) with ultrasound scan.

PURPOSE

The aim of this systematic review is to examine the evidence on benefits and harms of AAA screening.

SEARCH STRATEGY

This systematic review considered studies from the most recent United States Preventive Services Task Force review on AAA screening and passed through the screening process with citations identified in our search up to April 2015 (PROSPERO Registration #CRD42015019047).

RESULTS

For benefits of one-time AAA screening in men compared with controls, pooled analyses from four randomized controlled trials with moderate quality evidence showed significant reductions in AAA-related mortality and AAA rupture rate up to 13 to 15 years of follow-up with 42% reduction (risk ratio [RR], 0.58; 95% confidence interval [CI], 0.39-0.88; number needed to screen = 212) and 38% reduction (RR, 0.62; 95% CI, 0.45-0.86; number needed to screen = 200), respectively. The effect of on all-cause mortality was marginally significant for longer follow-up. The Chichester trial examined the benefits of one-time AAA screening in women and found no significant differences between screening and control arms for up to 10 years of follow-up (RR, 0.88; 95% CI, 0.72-1.07). For consequences of one-time AAA screening in men compared with controls, there was a significant increase in the total number of AAA-related procedures over a follow-up of 13 to 15 years (2.16 times more likely) compared with controls. For harms of one-time AAA screening, no significant differences were observed in 30-day postoperative mortality for elective and emergency operations with compared control groups. Evidence from the Multicenter Aneurysm Screening Study trial using 13-year follow-up data showed that one-time AAA screening with ultrasound scan was potentially associated with an overdiagnosis of 45% (95% CI, 42%-47%) among screen-detected men.

CONCLUSIONS

Population-based screening for AAA with ultrasound scan in asymptomatic men aged 65 years and older showed statistically significant reductions in AAA-related mortality and rupture and, hence, avoids unnecessary AAA-related deaths. The current evidence showed no benefit of one-time AAA screening in woman. Limited evidence is available on the benefits of repeat AAA screening and targeted screening approaches based on risk factors for AAA. Future research should explore the differential benefits of AAA screening based on risk factors that increase risk for developing AAA.

Laparoscopic surgery for elective abdominal aortic aneurysm repair

BACKGROUND

Abdominal aortic aneurysm (AAA) is an abnormal dilatation of the infradiaphragmatic aorta that is equal to or greater than 30 mm or a local dilatation of equal to or greater than 50% compared to the expected normal diameter of the artery. AAAs rarely occur in individuals under 50 years of age, but thereafter the prevalence dramatically increases with age, with men at a six-fold greater risk of developing an AAA than women. Prevalence of AAA has been reported to range from 1.3% in women aged 65 to 80 years to between 4% and 7.7% in men aged 65 to 80 years.There is evidence that the risk of rupture increases as the aneurysm diameter increases from 50 mm to 60 mm. People with AAAs over 55 mm in diameter are therefore generally referred for consideration of repair, as the risk of rupture exceeds the risk of repair. The traditional treatment for AAA is open surgical repair (OSR) which involves a large abdominal incision and is associated with a significant risk of complications. Two less invasive procedures have recently become more widely used: endovascular aneurysm repair (EVAR) and laparoscopic repair. EVAR is carried out through sheaths inserted in the femoral artery in the groin: thereafter, a stent graft is placed within the aneurysm sac under radiological image guidance and anchored in place to form a new channel for blood flow. Laparoscopic repair involves the use of a laparoscope which is inserted through small cuts in the abdomen and the synthetic graft is sewn in place to replace the weakened area of the aorta. Laparoscopic AAA repair falls into two categories: hand-assisted laparoscopic surgery (HALS), where an incision is made to allow the surgeon's hand to assist in the repair; and total laparoscopic surgery (TLS). Both EVAR and laparoscopic repair are favourable over OSR as they are minimally invasive, less painful, associated with fewer complications and lower mortality rate and have a shorter duration of hospital stay.Current evidence suggests that elective laparoscopic AAA repair has a favourable safety profile comparable with that of EVAR, with low conversion rates as well as similar mortality and morbidity rates. As a result, it has been suggested that elective laparoscopic AAA repair may have a role in treating those patients for whom EVAR is unsuitable.

OBJECTIVES

To assess the effects of laparoscopic surgery for elective abdominal aortic aneurysm repair.The primary objective of this review was to assess the perioperative mortality and operative time of laparoscopic (total and hand-assisted) surgical repair of abdominal aortic aneurysms (AAA) compared to traditional open surgical repair or EVAR. The secondary objective was to assess complication rates, all-cause mortality (> 30 days), hospital and intensive care unit (ICU) length of stay, conversion and re-intervention rates, and quality of life associated with laparoscopic (total and hand-assisted) surgical repair compared to traditional open surgical repair or EVAR.

SEARCH METHODS

The Cochrane Vascular Information Specialist (CIS) searched the Specialised Register (last searched August 2016) and CENTRAL (2016, Issue 7). In addition the CIS searched trials registries for details of ongoing or unpublished studies. We searched the reference lists of relevant articles retrieved by electronic searches for additional citations.

SELECTION CRITERIA

Randomised controlled trials and controlled clinical trials in which patients with an AAA underwent elective laparoscopic repair (total laparoscopic repair or hand-assisted laparoscopic repair) compared with either open surgical repair or EVAR.

DATA COLLECTION AND ANALYSIS

Studies identified for potential inclusion were independently assessed for inclusion by at least two review authors.

MAIN RESULTS

One randomised controlled trial with a total of 100 male participants was included in the review. The trial compared hand-assisted laparoscopic repair with EVAR and provided results for in-hospital mortality, operative time, length of hospital stay and lower limb ischaemia. The included study did not report on the other pre-planned outcomes of this review. No in-hospital deaths occurred in the study. Hand-associated laparoscopic repair was associated with a longer operative time (MD 53.00 minutes, 95% CI 36.49 to 69.51) than EVAR. The incidence of lower limb ischaemia was similar between the two treatment groups (risk ratio (RR) 0.50, 95% confidence interval (CI) 0.05 to 5.34). The mean length of hospital stay was 4.2 days and 3.4 days in the hand-assisted laparoscopic repair and EVAR groups respectively but standard deviations were not reported and therefore it was not possible to independently test the statistical significance of this result. The quality of evidence was downgraded for imprecision due to the inclusion of one small study; and wide confidence intervals and indirectness due to the study including male participants only. No study compared laparoscopic repair (total or hand-assisted) with open surgical repair or total laparoscopic surgical repair with EVAR.

AUTHORS' CONCLUSIONS

There is insufficient evidence to draw any conclusions about effectiveness and safety of laparoscopic (total and hand-assisted) surgical repair of AAA versus open surgical repair or EVAR, because only one small randomised trial was eligible for inclusion in this review. High-quality randomised controlled trials are needed.

Abdominal aortic aneurysm screening program using hand-held ultrasound in primary healthcare

We determined the feasibility of abdominal aortic aneurysm (AAA) screening program led by family physicians in public primary healthcare setting using hand-held ultrasound device. The potential study population was 11,214 men aged ≥ 60 years attended by three urban, public primary healthcare centers. Participants were recruited by randomly-selected telephone calls. Ultrasound examinations were performed by four trained family physicians with a hand-held ultrasound device (Vscan^®). AAA observed were verified by confirmatory imaging using standard ultrasound or computed tomography. Cardiovascular risk factors were determined. The prevalence of AAA was computed as the sum of previously-known aneurysms, aneurysms detected by the screening program and model-based estimated undiagnosed aneurysms. We screened 1,010 men, with mean age of 71.3 (SD 6.9) years; 995 (98.5%) men had normal aortas and 15 (1.5%) had AAA on Vscan^®. Eleven out of 14 AAA-cases (78.6%) had AAA on confirmatory imaging (one patient died). The total prevalence of AAA was 2.49% (95%CI 2.20 to 2.78). The median aortic diameter at diagnosis was 3.5 cm in screened patients and 4.7 cm (p<0.001) in patients in whom AAA was diagnosed incidentally. Multivariate logistic regression analysis identified coronary heart disease (OR = 4.6, 95%CI 1.3 to 15.9) as the independent factor with the highest odds ratio. A screening program led by trained family physicians using hand-held ultrasound was a feasible, safe and reliable tool for the early detection of AAA.

Circulating microRNAs signature correlates with positive [18F]fluorodeoxyglucose-positron emission tomography in patients with abdominal aortic aneurysm

BACKGROUND

Prediction of abdominal aortic aneurysm (AAA) rupture is a challenging issue. Small noncoding microRNAs (miRNAs) are potent regulators of gene expression and are considered as valuable circulating biomarkers. Recently, [¹⁸F]fluorodeoxyglucose (FDG) uptake detected by positron emission tomography (PET) in AAA was correlated with cellular and molecular alterations involved in wall instability and its potential rupture. Our study aimed at identifying circulating miRNAs correlated with a positive PET that could help discriminate patients at high risk of rupture.

METHODS

The level of 372 miRNAs was evaluated by polymerase chain reaction array in plasma from 35 AAA patients displaying no FDG uptake (A0) and 22 patients with a positive PET uptake (A+). The modulated miRNAs were validated by quantitative polymerase chain reaction and measured in aneurysmal tissues from both groups of patients.

RESULTS

Six circulating miRNAs were found significantly modulated in A+ vs A0 patients. They were significantly correlated not only between them but also with the intensity of FDG uptake. Two of them correlated also with the AAA diameter. These miRNAs displayed significant discriminating power between the A+ and A0 groups as determined by receiver operating characteristic curves. Three downregulated circulating miRNAs (miR-99b-5p, miR-125b-5p, and miR-204-5p) were also significantly reduced in the aneurysmal tissue, specifically in the FDG-uptake site, compared with a negative zone in the same aneurysm and with A0 aneurysms. They were further significantly inversely correlated with the expression, at the positive uptake site, of some of their potential gene targets, most notably matrix metalloproteinase 13.

CONCLUSIONS

Six miRNAs were identified as potential new circulating biomarkers of PET+ AAA. Three of these were similarly modulated in the metabolically active aneurysmal wall and might be directly involved in AAA instability.

Fenofibrate in the management of AbdoMinal aortic anEurysm (FAME): study protocol for a randomised controlled trial

Background

Abdominal aortic aneurysm (AAA) is a slowly progressive destructive process of the main abdominal artery. Experimental studies indicate that fibrates exert beneficial effects on AAAs by mechanisms involving both serum lipid modification and favourable changes to the AAA wall.

Methods/design

Fenofibrate in the management of AbdoMinal aortic anEurysm (FAME) is a multicentre, randomised, double-blind, placebo-controlled clinical trial to assess the effect of orally administered therapy with fenofibrate on key pathological markers of AAA in patients undergoing open AAA repair. A total of 42 participants scheduled for an elective open AAA repair will be randomly assigned to either 145 mg of fenofibrate per day or identical placebo for a minimum period of 2 weeks prior to surgery. Primary outcome measures will be macrophage number and osteopontin (OPN) concentration within the AAA wall as well as serum concentrations of OPN. Secondary outcome measures will include levels of matrix metalloproteinases and proinflammatory cytokines within the AAA wall, periaortic fat and intramural thrombus and circulating concentrations of AAA biomarkers.

Discussion

At present, there is no recognised medical therapy to limit AAA progression. The FAME trial aims to assess the ability of fenofibrate to alter tissue markers of AAA pathology.

Trial registration

Australian New Zealand Clinical Trials Registry, ACTRN12612001226897. Registered on 20 November 2012.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1752-z) contains supplementary material, which is available to authorized users.

A Meta-Analysis of the Association of Chronic Obstructive Pulmonary Disease with Abdominal Aortic Aneurysm Presence

BACKGROUND

Several case-control and population-based abdominal aortic aneurysm (AAA) screening studies have reported inconclusive results of the association of chronic obstructive pulmonary disease (COPD) with AAA presence. To determine whether COPD is associated with AAA presence, we performed a meta-analysis of contemporary clinical studies.

METHODS

To identify all contemporary case-control and population-based AAA screening studies evaluating the association of COPD with AAA presence, databases including MEDLINE and EMBASE were searched from January 2000 to May 2015 using Web-based search engines (PubMed and OVID). An adjusted odds ratio (OR) and 95% confidence intervals (CI) for COPD or AAA presence (using multivariable logistic regression) were abstracted from each individual study. We took an OR for AAA presence to be representative of an OR for COPD presence.

RESULTS

Of 159 potentially relevant articles screened initially, there were 7 case-control and 4 population-based AAA screening studies that met eligibility requirements and were included. Pooled analysis of all the 11 studies (14 estimates, 155,731 participants), 7 case-control studies (4171 participants), and 4 population-based AAA screening studies (7 estimates, 151,560 participants) respectively demonstrated a statistically significant 1.78-fold (OR 1.78, 95% CI 1.38-2.30, P < 0.00001), 3.05-fold (OR 3.05, 95% CI 1.44-6.49, P = 0.004), and 1.24-fold (OR 1.24, 95% CI 1.04-1.48, P = 0.02) increased prevalence/incidence of COPD in patients with AAA relative to subjects without AAA (i.e., a statistically significant 1.78-, 3.05-, and 1.24-fold increased prevalence/incidence of AAA in patients with COPD relative to subjects without COPD) (P for subgroup differences = 0.02).

CONCLUSION

The present meta-analysis demonstrated 1.8-fold increased prevalence/incidence of COPD in patients with AAA relative to subjects without AAA (i.e., 1.8-fold increased prevalence/incidence of AAA in patients with COPD relative to subjects without COPD), which suggests that COPD is associated with AAA presence.

Current trends of major arterial diseases in Korea: based on data from the Health Insurance Review and Assessment Service

Purpose

This study aims to figure out the changes of the prevalence and management of carotid arterial occlusive diseases (CAOD), abdominal aortic diseases (AAA), and arterial diseases of the lower extremities (LAOD) in Korea over the past 5 years.

Methods

Data were extracted from the Health Insurance Review and Assessment Service during the period from 2008 to 2012.

Results

The number of patients with CAOD increased by about 30% every year. From the year 2008, the number of open surgeries (OS) and endovascular treatments (ET) increased by more than 20% during each of the first 2 years and by 10% every year for 3 years thereafter for CAOD. ET was preferred to OS and occupied 77%–79% of the total number of procedures. The number of patients with AAA increased by 11%–17% every year. ET for AAA occupied 52% of the total number of procedures in 2008 and gradually increased to 70% in 2012. The number of patients who were diagnosed with LAOD fluctuated over the five years. The total number of procedures to treat LAOD increased each year by 20%–25%. ET for LAOD constantly increased by 18%–24% each year and occupied 80%–95% of the total number of procedures.

Conclusion

It is evident that the incidence of vascular diseases will be increasing as our society ages, not to mention its care costs. The need for long-range plans and guidelines are urgent.

Epidemiology, Clinical Features, and Prescribing Patterns of Aortic Aneurysm in Asian Population From 2005 to 2011

Aortic aneurysm (AA) is a leading cause of death in Asia and the world. The prevalence in Western countries is around 1.3% to 8%. However, it is still unclear about the incidence, prevalence, and mortality of AA in Asian population. The aim of this study is to investigate the epidemiology of AA for all subtypes in Taiwan, and describe the clinical features and prescribing patterns for AA population.A population-based study was conducted using information from National Health Insurance Research Database (NHIRD) in Taiwan. Patients who were diagnosed with AA and also received computed tomography (CT) were included in this study. Incidence, prevalence, and mortality were calculated in each year during 2005 to 2011. Prevalent comorbidities and prescribing patterns were both evaluated among study population.The average annual incidence of AA in Taiwan was 7.35 per 100,000 population, and the prevalence was 29.04 per 100,000 population. It showed an increased trend of incidence from 2005 to 2011, so as prevalence and mortality. The incidence was associated with age and sex difference. It was much higher in those older than 65 years, especially for male. Hypertension, coronary artery disease (CAD), and chronic obstructive pulmonary disease (COPD) were prevalent comorbidities. Eighty-eight percentages of patients were prescribed antihypertensive agents in acute phase, where 61.4% of calcium channel blocker (CCB) was the most one.Our study found that incidence of AA was lower in Taiwan than in other countries. Nevertheless, it showed an increased trend of AA disease for incidence, prevalence, and also mortality during 2005 to 2011.

Population-Based Study of Incidence of Acute Abdominal Aortic Aneurysms With Projected Impact of Screening Strategy

BACKGROUND

Current abdominal aortic aneurysm (AAA) screening in men age 65 might have limited impact on overall AAA death rates if incidence is moving to older ages. Up-to-date population-based studies of age-specific incidence, risk factors, and outcome of acute AAA are needed to inform screening policy.

METHODS AND RESULTS

In a prospective, population-based study (Oxfordshire, UK, 2002-2014), the incidence and outcome of acute AAA events were determined. Based on population projections and current incidence trends, the impact of screening strategies in the UK was estimated. Over the 12-year period, 103 incident acute AAA events occurred in the study population of 92 728. Incidence/100 000/year was 55 in men ages 65 to 74 years, but increased to 112 at 75 to 85 and 298 at ≥85, with 66.0% of all events occurring at age ≥75 years. Incidence at ages 65 to 74 was highest in male smokers (274), with 96.4% of events in men <75 years occurring in ever-smokers. Extrapolating rates to the UK population, using trial evidence of screening efficacy, the current UK screening program would prevent 5.6% of aneurysm-related deaths (315 200 scans/year: 1426/death prevented, 121/year-of-life saved). Screening only male smokers age 65 and then all men at age 75 would prevent 21.1% of deaths (247 900 scans/year; 297/death prevented, 34/year-of-life saved). By 2030, 91.0% of deaths will occur at age ≥75, 61.6% at ≥85, and 28.6% in women.

CONCLUSIONS

Given that two thirds of acute AAA occurred at ≥75 years of age, screening older age groups should be considered. Screening nonsmokers at age 65 is likely to have very little impact on AAA event rates.

Screening for abdominal aortic aneurysm

Guidelines are systematically developed statements to assist patients and providers in choosing appropriate health care for specific clinical conditions. Consensus exists across guidelines on one-time screening of elderly men to detect and treat abdominal aortic aneurysm (AAA) ≥5.5 cm. However, the recommendations regarding other age groups, imaging intervals for small AAAs, inclusion of women, and cost-effectiveness have not been universally adopted. As many countries are considering the initiation of an AAA screening program, this is an overview on the current status of such programs.

Age-specific incidence, risk factors and outcome of acute abdominal aortic aneurysms in a defined population

BACKGROUND

Contemporary population-based data on age-specific incidence and outcome from acute abdominal aortic aneurysm (AAA) events are needed to understand the impact of risk factor modification and demographic change, and to inform AAA screening policy.

METHODS

In a prospective population-based study (Oxfordshire, UK, 2002-2014), event rates, incidence, early case fatality and long-term outcome from all acute AAA events were determined, both overall and in relation to the four main risk factors: smoking, hypertension, male sex and age.

RESULTS

Over the 12-year interval, 103 incident acute AAA events occurred in the study population of 92,728 (men 72·8 per cent; 59·2 per cent 30-day case fatality rate). The incidence per 100,000 population per year was 55 in men aged 65-74 years, but increased to 112 at age 75-84 years and to 298 at age 85 years or above. Some 66·0 per cent of all events occurred in those aged 75 years or more. The incidence at 65-74 years was highest in male smokers (274 per 100,000 population per year); 27 (96 per cent) of 28 events in men aged less than 75 years occurred in ever-smokers. Mean(s.d.) age at event was lowest in current smokers (72·2(7·2) years), compared with that in ex-smokers (81·2(7·0) years) and never-smokers (83·3(7·9) years) (P < 0·001). Hypertension was the predominant risk factor in women (diagnosed in 93 per cent), with 20 (71 per cent) of all 28 events in women occurring in those aged 75 years or above with hypertension. The 30-day case fatality rate increased from 40 per cent at age below 75 years to 69 per cent at age 75 years or more (P = 0·008).

CONCLUSION

Two-thirds of acute AAA events occurred at age 75 years or above, and more than 25 per cent of events were in women. Taken with the strong associations with smoking and hypertension, these findings could have implications for AAA screening.

The similarities and differences among patients with abdominal aortic aneurysms referred to a tertiary hospital and found at necropsy

OBJECTIVE

To analyze the characteristics of patients with abdominal aortic aneurysms referred to a tertiary center and to compare with individuals with abdominal aortic aneurysm found at necropsy.

METHODS

We have retrospectively analyzed the medical records of 556 patients with abdominal aortic aneurysm and 102 cases abdominal aortic aneurysm found at necropsy.

RESULTS

At univariated analysis, hypertension, tobacco use and maximum diameter were significant risk factors for symptomatic aneurysm, while diabetes tended to be a protective factor for rupture. By logistic regression analysis, the largest transverse diameter was the only one significantly associated with abdominal aortic aneurysm rupture (p < .0001, odds ratio 1.7, 95% confidence interval 1.481-1.951). Intact abdominal aortic aneurysm found at necropsy showed similarities with outpatients in relation to abdominal aortic aneurysm diameter and risk factors.

CONCLUSION

Intact abdominal aortic aneurysm at necropsy and at outpatients setting showed similarities that confirmed that abdominal aortic aneurysm repair is less offered to women, and they died more frequently with intact abdominal aortic aneurysm from other causes.

Monocyte activity is linked with abdominal aortic aneurysm diameter

BACKGROUND

Systemic inflammation and increased matrix metalloproteinase (MMP) cause elastin degradation leading to abdominal aortic aneurysm (AAA) expansion. Several prospective studies report that statin therapy can reduce AAA expansion through anti-inflammation. We hypothesize that monocyte activity plays a pivotal role in this AAA development and this study examines patient peripheral blood monocyte cell adhesion, transendothelial migration, and MMP concentrations between AAA and non-AAA patients.

MATERIALS AND METHODS

Peripheral blood was collected and monocytes isolated from control (n=15) and AAA (n=13) patients. Monocyte adhesion, transmigration, and permeability assays were assessed. Luminex assays determined MMP-9 and tissue inhibitor of metalloproteinase-4 (TIMP-4) concentrations from cell culture supernatant and patient serum.

RESULTS

AAA patient monocytes showed increased adhesion to the endothelium relative fluorescence units (RFU, 0.33±0.17) versus controls (RFU, 0.13±0.04; P=0.005). Monocyte transmigration was also increased in AAA patients (RFU, 0.33±0.11) compared with controls (RFU, 0.25±0.04, P=0.01). Greater numbers of adhesive (R2=0.66) and transmigratory (R2=0.86) monocytes were directly proportional to the AAA diameter. Significantly higher serum levels of MMP-9 (2149.14±947 pg/mL) were found in AAA patients compared with controls (1189.2±293; P=0.01). TIMP-4 concentrations were significantly lower in AAA patients (826.7±100 pg/mL) compared with controls (1233±222 pg/mL; P=0.02). Cell culture supernatant concentrations of MMP and TIMP from cocultures were higher than monocyte-only cultures.

CONCLUSIONS

Monocytes from AAA patients have greater adhesion and transmigration through the endothelium in vitro, leading to elevated MMP-9 levels and the appropriate decrease in TIMP-4 levels. The ability to modulate monocyte activity may lead to novel medical therapies to decrease AAA expansion.

Outcomes of an abdominal aortic aneurysm screening program

OBJECTIVE

In 2007, Medicare guidelines were established to identify persons at risk for the presence of an abdominal aortic aneurysm (AAA). The purpose of this study is to evaluate the 5-year outcomes of an AAA screening program in a regional Veterans Affairs (VA) health care system.

METHODS

Data were extracted from a regional VA health care network identifying all veteran males 65 to 75 years of age who smoked at least 100 cigarettes during their lifetime. In 2007, an AAA screening mandate was implemented allowing patients meeting screening criteria to be evaluated for AAA as part of the patient's health maintenance. AAA is identified as an aortic diameter size of 3.0 cm or greater. Clinician adherence to screening protocols and referral to a vascular surgeon for aneurysms >5.5 cm were also evaluated.

RESULTS

A total of 9751 patients (71.5 ± 5.6 standard deviation years of age) were screened for an AAA over a 5-year period from January 1, 2007 to December 31, 2011. A total of 698 aneurysms (7.1%) were found. Referrals to a vascular surgeon were made on 45 patients with aneurysms >5.5 cm. Over a 5-year period, a total of 2754 patients (28.2%) were inappropriately screened: 416 patients were under 65 years old, 2243 patients were over 75 years old, 36 patients were women, and 123 patients without aneurysms had multiple screenings. In 2007, during the first year of implementation, 39.2% of patients were inappropriately screened. Over the next 4 years, inappropriate screenings decreased with 33.7% in 2008, 28.6% in 2009, 17.7% in 2010, and 14.3% in 2011.

CONCLUSIONS

A large AAA screening program at the VA detects more aneurysms, but at smaller diameters than that published in clinical trials. Over time, the number of inappropriate AAA screenings has continued to decrease, demonstrating greater awareness and application of the AAA screening guidelines by primary care providers. Developing surveillance guidelines for small and medium aneurysms is a potential area for future research.

Final follow-up of the Multicentre Aneurysm Screening Study (MASS) randomized trial of abdominal aortic aneurysm screening

BACKGROUND

The long-term effects of abdominal aortic aneurysm (AAA) screening were investigated in extended follow-up from the UK Multicentre Aneurysm Screening Study (MASS) randomized trial.

METHODS

A population-based sample of men aged 65-74 years were randomized individually to invitation to ultrasound screening (invited group) or to a control group not offered screening. Patients with an AAA (3·0 cm or larger) detected at screening underwent surveillance and were offered surgery after predefined criteria had been met. Cause-specific mortality data were analysed using Cox regression.

RESULTS

Some 67 770 men were enrolled in the study. Over 13 years, there were 224 AAA-related deaths in the invited group and 381 in the control group, a 42 (95 per cent confidence interval 31 to 51) per cent reduction. There was no evidence of effect on other causes of death, but there was an overall reduction in all-cause mortality of 3 (1 to 5) per cent. The degree of benefit seen in earlier years of follow-up was slightly diminished by the occurrence of AAA ruptures in those with an aorta originally screened normal. About half of these ruptures had a baseline aortic diameter in the range 2·5-2·9 cm. It was estimated that 216 men need to be invited to screening to save one death over the next 13 years.

CONCLUSION

Screening resulted in a reduction in all-cause mortality, and the benefit in AAA-related mortality continued to accumulate throughout follow-up.

REGISTRATION NUMBER

ISRCTN37381646 (http://www.controlled-trials.com).

Monocytic adhesion molecule expression and monocyte-endothelial cell dysfunction are increased in patients with peripheral vascular disease versus patients with abdominal aortic aneurysms

BACKGROUND

Statin therapy is used in the medical management of patients with peripheral vascular disease (PVD) and abdominal aortic aneurysm (AAA) for the pleiotropic and anti-inflammatory benefits. We hypothesize that the inflammatory mechanisms of monocyte-endothelial cell interactions in endothelial barrier dysfunction are more significant in patients with PVD compared with those with AAA. The purpose of this study was to assess patient peripheral blood monocyte adhesion molecules by flow cytometry and monocyte-induced endothelial barrier dysfunction by using an in vitro endothelial cell layer and electric cell-substrate impedance sensing (ECIS) system.

METHODS

Peripheral blood was collected from patients with either PVD (ankle-brachial index <0.9, toe-arm index <0.8, or required lower extremity vascular intervention) or AAA (aortic diameter >3.0 cm). Monocytes were isolated from fresh whole blood using an accuspin-histopaque technique. The separated monocytes underwent flow cytometry analysis to evaluate the expression levels of the cell membrane adhesion molecules: CD18, CD11a/b/c, and very late antigen-4. Endothelial cell function was assessed by adding monocytes to an endothelial monolayer on ECIS arrays and coculturing overnight. Peak changes in transendothelial electrical resistance were measured and compared between patient groups.

RESULTS

Twenty-eight monocyte samples were analyzed for adhesion molecules (PVD, 19 and AAA, 9) via flow cytometry, and 11 patients were evaluated for endothelial dysfunction (PVD, 7 and AAA, 4) via ECIS. There was no significant difference between risk factors among PVD and AAA patients except for age, where AAA patients were significantly older than PVD patients in both flow cytometry and ECIS groups (P=0.02 and 0.01, respectively). There were significantly higher levels of adhesion molecules CD11a, CD18, and CD11c (averaged mean fluorescent intensity P values: 0.047, 0.038, and 0.014, respectively) in PVD patients compared with AAA patients. No significant difference was found for CD11b and very late antigen-4 expression (P=0.21 and 0.15, respectively). There was significantly more monocyte-endothelial cell dysfunction in patients with PVD versus patients with AAA, with a maximal effect seen at 15h after monocyte addition (P=0.032).

CONCLUSIONS

Patients with PVD have increased expression levels of certain monocyte adhesion molecules and greater monocyte-induced endothelial layer dysfunction compared with those with AAA. This may lead to other methods of targeted therapy to improve outcomes of these vascular patients.

Meta-analysis of individual patient data to examine factors affecting growth and rupture of small abdominal aortic aneurysms

Background

Surveillance is a common management strategy for small abdominal aortic aneurysm (AAA) (3·0–5·4 cm in diameter). Individual characteristics, other than diameter, may influence aneurysm growth or rupture rates.

Methods

Individual data were collated from 15 475 people under follow-up for a small aneurysm in 18 studies. The influence of co-variables (including demographics, medical and drug history) on aneurysm growth and rupture rates (analysed using longitudinal random-effects modelling and survival analysis with adjustment for aneurysm diameter) were summarized in an individual patient meta-analysis.

Results

The mean aneurysm growth rate of 2·21 mm/year was independent of age and sex. Growth rate was increased in smokers (by 0·35 mm/year) and decreased in patients with diabetes (by 0·51 mm/year). Mean arterial pressure had no effect and antihypertensive or other cardioprotective medications had only small, non-significant effects on aneurysm growth, consistent with the observation that calendar year of enrolment was not associated with growth rate. Rupture rates were almost fourfold higher in women than men (P &lt; 0·001), were double in current smokers (P = 0·001) and increased with higher blood pressure (P = 0·001).

Conclusion

Follow-up schedules for individuals with a small AAA may need to consider diabetes and smoking, in addition to aneurysm diameter. The differing risk factors for growth and rupture suggest that a lower threshold for surgical intervention in women may be justified. No single drug used for cardiovascular risk reduction had a major effect on the growth or rupture of small aneurysms.

What is the role of screening in the management of abdominal aortic aneurysms?

A best-evidence topic in vascular surgery was written according to a structured protocol. The question addressed was whether screening asymptomatic individuals for an abdominal aortic aneurysm (AAA) is feasible and improves disease-free survival. Seven studies presented the best evidence to answer the clinical question. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results and limitations of the studies are tabulated. In total, four randomized population-based studies have evaluated ultrasound screening for AAA: two British studies, Multicentre Aneurysm Screening Study (MASS) and the Chichester trial, and one each in Viborg County, Denmark and Western Australia. Participants were randomized to receive an invitation to screen or not. The MASS trial randomized 67 770 men, followed participants over 10 years and concluded that screening would almost half AAA-related deaths in men aged 65-74 years. The smaller Chichester trial included only 6040 men but demonstrated a 42% reduction in AAA-related mortality at 5 years, with ongoing benefit at 15 years (11% reduction). The Viborg County trial recruited 12 639 men aged 64-73 years, showed a 66% reduction in AAA-related mortality over 14 years. Finally, the Western Australia trial evaluated 41 000 men but included an older population of 65-83 years old. No benefit was seen in this age group but subgroup analysis of men aged 65-74 showed a significant mortality benefit. Only a small or insignificant benefit in all-cause mortality was seen in any of these studies. A recent meta-analysis of these trials has shown a significant benefit in AAA-related mortality in the long term and concluded that AAA screening is superior to other established screening programmes. The cost-effectiveness of screening was assessed in the MASS and Viborg County trials and was found to be substantially below the cost threshold set by the National Institute of Clinical Excellence for acceptance of interventions. Quality of life was assessed in the MASS and in a case-control study and showed no adverse effects that outweigh the benefits. We concluded that ultrasound screening for AAAs has met all the criteria to become a screening programme and would substantially reduce disease-related death with no adverse effect on quality of life.

Low prevalence of abdominal aortic aneurysm among 65-year-old Swedish men indicates a change in the epidemiology of the disease

BACKGROUND

Screening elderly men with ultrasound is an established method to reduce mortality from ruptured abdominal aortic aneurysm (AAA; Evidence Level 1a). Such programs are being implemented and generally consist of a single scan at 65 years of age. We report the results from screening 65-year-old men for AAA in middle Sweden.

METHODS AND RESULTS

All 65-year-old men (n=26,256), identified through the National Population Registry, were invited to an ultrasound examination. An AAA was defined as a maximum infrarenal aortic diameter of ≥30 mm. In total, 22 187 (85%) accepted, and 373 AAAs were detected (1.7%; 95% confidence interval, 1.5 to 1.9). With 127 previously known AAAs (repaired/under surveillance) included, the total prevalence of the disease in the population was 2.2% (95% confidence interval, 2.0 to 2.4). Self-reported smoking (odds ratio, 3.4; P<0.001), coronary artery disease (odds ratio, 2.0; P<0.001), and hypertension (odds ratio, 1.6; P=0.001) were independently associated with AAA in a multivariate logistic regression model. Thirteen percent of the entire population reported to be current smokers, one third of the frequency reported in the 1980s. The observed low prevalence of AAA was explained mainly by this change in smoking habits.

CONCLUSIONS

On the basis of the observed reduced exposure to risk factors, lower-than-expected prevalence of AAA among 65-year-old men, unchanged AAA repair rate, and significantly improved longevity of the elderly population, the current generally agreed-on AAA screening model can be questioned. Important issues to address are the threshold diameter for follow-up, the possible need for rescreening at a higher age, and selective screening among smokers.

Cost-effectiveness of screening for abdominal aortic aneurysm in the Netherlands and Norway

Background

The aim of this study was to determine the cost-effectiveness of ultrasound screening for abdominal aortic aneurysm (AAA) in men aged 65 years, for both the Netherlands and Norway.

Methods

A Markov model was developed to simulate life expectancy, quality-adjusted life-years, net health benefits, lifetime costs and incremental cost-effectiveness ratios for both screening and no screening for AAA. The best available evidence was retrieved from the literature and combined with primary data from the two countries separately, and analysed from a national perspective. A threshold willingness-to-pay (WTP) of €20 000 and €62 500 was used for data from the Netherlands and Norway respectively.

Results

The additional costs of the screening strategy compared with no screening were €421 (95 per cent confidence interval 33 to 806) per person in the Netherlands, and the additional life-years were 0·097 (−0·180 to 0·365), representing €4340 per life-year. For Norway, the values were €562 (59 to 1078), 0·057 (−0·135 to 0·253) life-years and €9860 per life-year respectively. In Norway the results were sensitive to a decrease in the prevalence of AAA in 65-year-old men to 1 per cent, or lower. Probabilistic sensitivity analyses indicated that AAA screening has a 70 per cent probability of being cost-effective in the Netherlands with a WTP threshold of €20 000, and 70 per cent in Norway with a threshold of €62 500.

Conclusion

Using this model, screening for AAA in 65-year-old men would be highly cost-effective in both the Netherlands and Norway.

Meta-analysis of postoperative mortality after elective repair of abdominal aortic aneurysms detected by screening

Background

The aim of this study was to compare the mortality rate within 30 days of elective surgery for abdominal aortic aneurysm (AAA) in men randomized to an invitation for ultrasound screening with that of men in the control group, whose aneurysms were detected incidentally.

Methods

Relevant reports from randomized trials of screening were identified through a systematic search of MEDLINE. Four relevant trials were identified, and supplemented with data from the Viborg Vascular screening trial. Data were updated in two studies. Meta-analysis was undertaken with effects calculated as a fixed odds ratio (OR) with 95 per cent confidence interval. Heterogeneity between the studies was assessed by the χ2 test.

Results

There were 25 deaths (2·9 per cent) following elective surgery in 858 men invited for screening compared with 21 (5·5 per cent) of 383 in the control group (OR 0·49, 0·27 to 0·88). There were 18 deaths (2·4 per cent) following elective surgery for 747 screen-detected AAAs compared with 28 (6·1 per cent) following elective repair of 459 incidentally detected aneurysms (OR 0·37, 0·20 to 0·68).

Conclusion

The offer of screening identifies men whose early survival following elective AAA repair is better than that of men with an AAA detected incidentally.

Diagnostic and therapeutic strategies for small abdominal aortic aneurysms

Abdominal aortic aneurysms (AAA) affect 5% of the population in developed countries and are characterized by progressive aortic dilatation with an unpredictable time course. This condition is more common in men than in women, and in smokers than in nonsmokers. If left untreated, AAA can result in aortic rupture and death. Pathologically, aortic extracellular matrix degradation, inflammation, and neovascularization are hallmarks of AAA. Diagnosis of AAA and subsequent surveillance utilize established aortic imaging methods, such as ultrasound, CT, and MRI. More-speculative diagnostic approaches include molecular and cellular imaging methods that interrogate the underlying pathological processes at work within the aneurysm. In this Review, we explore the current diagnostic and therapeutic strategies for the management of AAA. We also describe the diagnostic potential of new imaging techniques and therapeutic potential of new treatments for the management of small AAA.