Abdominal aortic aneurysm screening: how many life years lost from underuse of the medicare screening benefit?

Focus on the Most Common Paucisymptomatic Vasculopathic Population, from Diagnosis to Secondary Prevention of Complications

Middle-aged adults can start to be affected by some arterial diseases (ADs), such as abdominal aortic or popliteal artery aneurysms, lower extremity arterial disease, internal carotid, or renal artery or subclavian artery stenosis. These vasculopathies are often asymptomatic or paucisymptomatic before manifesting themselves with dramatic complications. Therefore, early detection of ADs is fundamental to reduce the risk of major adverse cardiovascular and limb events. Furthermore, ADs carry a high correlation with silent coronary artery disease (CAD). This study focuses on the most common ADs, in the attempt to summarize some key points which should selectively drive screening. Since the human and economic possibilities to instrumentally screen wide populations is not evident, deep knowledge of semeiotics and careful anamnesis must play a central role in our daily activity as physicians. The presence of some risk factors for atherosclerosis, or an already known history of CAD, can raise the clinical suspicion of ADs after a careful clinical history and a deep physical examination. The clinical suspicion must then be confirmed by a first-level ultrasound investigation and, if so, adequate treatments can be adopted to prevent dreadful complications.

Identification and characterization of new candidates for abdominal aortic aneurysm screening in patients outside of current accepted guidelines

BACKGROUND

Previous studies have identified groups of patients with abdominal aortic aneurysm (AAA) that fall outside of currently accepted screening guidelines. Population-based studies have found AAA screening would be cost-effective at a prevalence of 0.5% to 1.0%. The goal of this study was to determine the prevalence of AAA in patients that fall outside of the current screening guidelines. In addition, we analyzed outcomes of the groups with a prevalence of greater than 1%.

METHODS

Using the TriNetX Analytics Network, several patient cohorts were abstracted with a diagnosis of ruptured or unruptured AAA based on previously identified groups with a potentially high risk for AAA that fall outside of currently accepted screening guidelines. Groups were also stratified by sex. For groups found to have a prevalence of greater than 1%, the unruptured patients were further analyzed for long-term rates of rupture and included male ever-smokers aged 45 to 65, male never-smokers aged 65 to 75, male never-smokers aged greater than 75, and female ever-smokers aged 65 or greater. Long-term mortality, stroke, and myocardial infarction rates were compared in patients with treated and untreated AAA after propensity score matching.

RESULTS

We identified 148,279 patients across the four groups with a prevalence of AAA of greater than 1% with female ever-smokers aged 65 or older being the most prevalent (2.73%). In each of the four groups, the rate of AAA rupture increased every 5 years and all had rupture rates of greater than 1% at 10 years. Meanwhile, controls for each of these four subgroups without a previous AAA diagnosis had rupture rates between 0.090% and 0.013% at 10 years. Those who underwent repair of their AAA had decreased incidence of mortality, stroke, and myocardial infarction. Specifically, male ever-smokers aged 45 to 64 had a significant difference in incidence of mortality and myocardial infarction at 5 years and stroke at 1 and 5 years.

CONCLUSIONS

Our analysis suggests male ever-smokers aged 45 to 65, male never-smokers aged 65 to 75, male never-smokers aged greater than 75, and female ever-smokers aged 65 or greater have a more than 1% prevalence of AAA and, therefore, may benefit from screening. Outcomes were significantly worse compared with well-matched controls in these groups.

Abdominal aortic aneurysm monitoring via arterial waveform analysis: towards a convenient point-of-care device

Abdominal aortic aneurysms (AAAs) are lethal but treatable yet substantially under-diagnosed and under-monitored. Hence, new AAA monitoring devices that are convenient in use and cost are needed. Our hypothesis is that analysis of arterial waveforms, which could be obtained with such a device, can provide information about AAA size. We aim to initially test this hypothesis via tonometric waveforms. We study noninvasive carotid and femoral blood pressure (BP) waveforms and reference image-based maximal aortic diameter measurements from 50 AAA patients as well as the two noninvasive BP waveforms from these patients after endovascular repair (EVAR) and from 50 comparable control patients. We develop linear regression models for predicting the maximal aortic diameter from waveform or non-waveform features. We evaluate the models in out-of-training data in terms of predicting the maximal aortic diameter value and changes induced by EVAR. The best model includes the carotid area ratio (diastolic area divided by systolic area) and normalized carotid-femoral pulse transit time ((age·diastolic BP)/(height/PTT)) as input features with positive model coefficients. This model is explainable based on the early, negative wave reflection in AAA and the Moens-Korteweg equation for relating PTT to vessel diameter. The predicted maximal aortic diameters yield receiver operating characteristic area under the curves of 0.83 ± 0.04 in classifying AAA versus control patients and 0.72 ± 0.04 in classifying AAA patients before versus after EVAR. These results are significantly better than a baseline model excluding waveform features as input. Our findings could potentially translate to convenient devices that serve as an adjunct to imaging.

Impact of Implicit Abdominal Aortic Aneurysm Screening in the Veterans Affairs Health Care System Over 10 Years

Background

Abdominal aortic aneurysm (AAA) screening programs have been active in the United States since 2005, but are not the only way AAAs are detected. AAA management and outcomes have not been investigated broadly in the context of “implicit AAA screening,” whereby radiologic examinations not intended for focused screening can identify AAAs.

Methods and Results

We examined the association between imaging‐based AAA screening, both explicit and implicit, and various outcomes for ≈1.6 million veterans in the Veterans Affairs health care system from 2005 to 2015. Screened‐positive, screened‐negative, and unscreened veterans were identified in the overall cohort and within a subgroup of veterans aged 65 years in 2005. The yearly composite screening rate increased over 10 years, from 11.7% to 18.3%, whereas the screened‐positive rate decreased from 7.3% to 4.9%. Only 12.9% of screening examinations were explicit AAA screening ultrasounds. The subgroup’s composite screening rate was 74% within its 10‐year eligibility window, with implicit screening accounting for 91.8% of examinations. In the 2005 subgroup, all‐cause mortality and Charlson comorbidity scores were higher for veterans who underwent screening compared with those unscreened (31.2% versus 23.1% and 0.47 versus 0.25, respectively; P<0.001). AAA rupture rates were similar between those unscreened and screened‐negative individuals.

Conclusions

Accounting for both explicit and implicit screening, AAA screening in the Veterans Affairs population has moderate reach. Efforts to expand explicit AAA screening are not likely to impact either all‐cause mortality or AAA rupture on the population scale as significantly as a careful accounting for and use of implicit screening data.

Overview of screening eligibility in patients undergoing ruptured AAA repair from 2003 to 2019 in the Vascular Quality Initiative

OBJECTIVE

Although efforts such as the Screening Abdominal Aortic Aneurysms Very Efficiently (SAAAVE) Act have improved access to abdominal aortic aneurysm (AAA) screening, certain high-risk populations are currently excluded from the guidelines yet may benefit from screening. We therefore examined all patients who underwent repair of ruptured AAA (rAAA) to characterize those who are ineligible for screening under current guidelines and evaluate the potential impact of these restrictions on their disease.

METHODS

We identified patients undergoing rAAA repair in the Vascular Quality Initiative (VQI) database between 2003 and 2019. These patients were stratified by AAA screening eligibility according to the Centers for Medicare and Medicaid reimbursement guidelines. We then described baseline characteristics to identify high-risk features of these cohorts. Groups with disproportionate representation in the screening-ineligible cohort were identified as potential targets of screening expansion. Trends over time in screening eligibility and the proportion of AAA repairs performed for rAAA were also analyzed.

RESULTS

A total of 5340 patients underwent rAAA repair. The majority (66%) were screening-ineligible. When characterizing the screening-ineligible group by sex and risk factors (smoking history or family history of AAA), the largest contributors to screening ineligibility were males less than 65 years of age with a smoking history or family history of AAA (25%), males greater than 75 years of age with a smoking history (25%), and females older than 65 years of age with a smoking history (19%). In comparison with rAAAs prior to implementation of the SAAAVE act, the proportion of AAA repair performed for rupture among males undergoing AAA repair in the VQI decreased from 12% to 8% (P < .001), whereas in females, there was no change (P = .990). There was no statically significant difference in screening eligibility for either males (P = .762) or females (P = .335).

CONCLUSIONS

Most patients who underwent rAAA repair were ineligible for initial AAA screening or aged out of the screening window. Furthermore, rAAA rates and screening ineligibility have not improved as much as expected since the passage of the SAAAVE Act. Our data suggest that three high-risk populations may benefit from expansion of AAA screening guidelines: males with a smoking history or family history of AAA between ages 55 and 64 years, female smokers older than 65 years, and male smokers older than 75 years who are otherwise in good health. Increased efforts to screen these high-risk populations may increase elective AAA repair and minimize the morbidity and mortality associated with rAAAs.

Sex-Based Disparities in Outcomes With Abdominal Aortic Aneurysms

Although abdominal aortic aneurysms (AAA) are more common in men, women with AAA have increased morbidity and mortality. Additionally, there are discrepancies among professional society guidelines for AAA screening in women. In this retrospective study from the Nationwide Inpatient Sample (NIS) database from 2003 to 2014, we compared rates of AAA repair (rupture and elective) and AAA-related mortality in men vs. women to identify predictors of death among men and women with AAA. We divided the population into 1) AAA rupture 2) elective AAA repair. The main outcomes included temporal trends in AAA rupture, rupture-related death, AAA repair, in-hospital death, and predictors of AAA-related death. There were 570,253 discharge records for AAA admissions between 2003 and 2014, including 22.8% women and 77.2% men. Women had a higher proportion of rupture (18.4% vs 12.6%, p <0.01). A smaller proportion of women underwent endovascular aortic repair (EVAR) compared with men in the ruptured AAA (13.9% vs. 20.3%, p <0.01) and elective repair (55.7% vs. 67.4%, p <0.01) cohorts. Within the ruptured cohort, a higher proportion of women did not receive repair (46.4% vs. 26.1%, p <0.01). On multivariable analysis, female gender was a significant predictor of death with rupture (OR 1.39, 95% CI 1.16 to 1.66) and elective repair (OR 1.74, 95% CI 1.36 to 2.22), with both elective EVAR (OR 2.52, 95% CI 2.06 to 3.09) and elective open aortic repair (OAR; OR 1.50, 95% CI 1.33 to 1.68). Propensity score matching confirmed a higher risk of death in women in both the rupture (OR 1.19, 95% CI 1.09 to 1.30) and elective repair (OR 1.50, 95% CI 1.35 to 1.67) cohorts. In conclusion, AAA poses significant morbidity and mortality, especially in women. Women were more likely to die before repair with AAA rupture and female gender was an independent predictor of mortality in both the rupture and elective repair groups.

Screening Older Adult Men for Abdominal Aortic Aneurysm: A Scoping Review

Abdominal aortic aneurysm (AAA) is a potentially fatal condition predominantly affecting older adult men (60 years or over). Based on evidence, preventative health-care guidelines recommend screening older males for AAA using ultrasound. In attempts to reduce AAA mortality among men, screening has been utilized for early detection in some Western countries including the UK and Sweden. The current scoping review includes 19 empirical studies focusing on AAA screening in men. The findings from these studies highlight benefits and potential harms of male AAA screening. The benefits of AAA screening for men include decreased incidence of AAA rupture, decreased AAA mortality, increased effectiveness of elective AAA repair surgery, and cost-effectiveness. The potential harms of AAA screening included lack of AAA mortality reduction, negative impacts on quality of life, and inconsistent screening eligibility criteria being applied by primary care practitioners. The current scoping review findings are discussed to suggest changes to AAA screening guidelines and improve policy and practice.

Abdominal aortic aneurysm screening: concepts and controversies

Abdominal aortic aneurysms (AAAs) are a leading cause mortality and morbidity but often go undiagnosed until late stages unless imaging is performed. In 2005, the United States Preventive Services Task Force (USPSTF) for the first time recommended one-time ultrasound screening for elderly male smokers and selective screening in other populations. These guidelines were reaffirmed and updated in 2014; a proposal for potential further revisions is now in early planning stages. In this article, we review the past and current USPSTF AAA screening recommendations and techniques for performing optimal screening. Evidence supporting screening and alternative guidelines are also discussed. In addition, emerging concepts and controversies in AAA screening are highlighted, including conflicting data on screening benefits, screening underutilization, inconsistent follow-up recommendations, and the potential for duplicative testing, alternative screening modalities, and clinically significant incidental findings.

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.

Screening for aortic aneurysms in patients with coronary artery disease: should it be done?

Aneurysmal dilation of the aorta is a clinically silent disease that often presents first with a catastrophic event. As a result, several clinician societies and organizations have recommended screening to detect aneurysms before they rupture. Although screening may reduce mortality, the implementation of screening has been poor. Cardiologists are uniquely positioned to improve this gap as they handle patients with typical risk factors for aneurysmal diseases of the aorta and can endorse and implement screening in a high-risk population. The following article attempts to concisely give a navigational tool to the cardiovascular specialist for her/his role in the diagnosis and management of thoracic and abdominal aortic aneurysms, citing evidence as well as stating opinions on how to improve outcomes in this unique patient population.