Epidemiology Of Abdominal Aortic Aneurysms Research Articles

Epidemiology of Abdominal Aortic Aneurysm Repair in Brazil from 2008 to 2019 and Comprehensive Review of Nationwide Statistics Across the World.

Studying epidemiology of abdominal aortic aneurysms repairs is essential to prevent related deaths. Although outcomes are influenced by socioeconomic factors, there are no nationwide studies on these statistics in low-and-middle income countries. Therefore, we designed this study to evaluate abdominal aortic aneurysms repair rates, trends, costs, and in-hospital mortality in the Brazilian Public Health System, which exclusively insures over 160 million Brazilians. Retrospective cross-sectional population-based analysis of publicly available data referring to all abdominal aortic aneurysm repairs performed between 2008 and 2019 in Brazilian public hospitals. We observed a total of 13,506 abdominal aortic aneurysm repairs, of which 32% were emergency endovascular repairs, 20% emergency open repairs, 32% elective endovascular repairs and 16% elective open repairs. There has been a downward trend in total abdominal aortic aneurysms repairs and an increasing predominance of endovascular repair. Elective and endovascular repairs were significantly associated with lower in-hospital mortality. For ruptured abdominal aortic aneurysms, we observed mortality rates of 13.8% after endovascular repair and 52.1% after open repair. For intact abdominal aortic aneurysms, we observed mortalities of 3.8% after endovascular repair and 18.6% after open repair. Procedure and mortality rates varied significantly among the Brazilian regions. We observed a low and decreasing rate of abdominal aortic aneurysm repair. Most repairs were emergency and endovascular and there was an increasing predominance of endovascular repair. Endovascular and elective repairs were associated with lower mortality.

Epidemiology of abdominal aortic aneurysms

Abdominal aortic aneurysm (AAA) disease remains a major source of morbidity in developed countries and can progress to life-threatening rupture if left untreated, with exceedingly high mortality. The goal of AAA management is to identify and electively repair AAAs before rupture. AAA disease burden and outcomes have improved over time with declining tobacco use and advancements in care across patients’ disease course. The introduction of endovascular AAA repair, in particular, has allowed for elective AAA repair in patients previously considered too high risk for open surgery and has contributed to lower rates of AAA rupture over time. However, these improved outcomes are not universally experienced, and disparities continue to exist in the detection, treatment, and outcomes of AAA by sex, race, and ethnicity. Mitigating these disparities requires enhanced, focused efforts at preventing disease, promoting health, and delivering appropriate care among an increasingly diverse patient population.

Trends in abdominal aortic aneurysm-related mortality in Brazil, 2000-2016: a multiple-cause-of-death study

OBJECTIVES:Remarkable changes in the epidemiology of abdominal aortic aneurysm (AAA) have occurred in many countries during last few decades, which have also affected Brazilian mortality concurrently. This study aimed to investigate mortality trends related to AAA mortality in Brazil from 2000 to 2016.METHODS:Annual AAA mortality data was extracted from the public databases of the Mortality Information System, and processed by the Multiple Cause Tabulator.RESULTS:In Brazil, 2000 through 2016, AAA occurred in 69,513 overall deaths; in 79.6% as underlying and in 20.4% as an associated cause of death, corresponding to rates respectively of 2.45, 1.95 and 0.50 deaths per 100,000 population; 65.4% male and 34.6% female; 60.6% in the Southeast region. The mean ages at death were 71.141 years overall, and 70.385 years and 72.573 years for men and women, respectively. Ruptured AAA occurred in 64.3% of the deaths where AAA was an underlying cause, and in 18.0% of the deaths where AAA was an associated cause. The standardized rates increased during 2000-2008, followed by a decrease during 2008-2016, resulting in an average annual percent change decline of -0.2 (confidence interval [CI], -0.5 to 0.2) for the entire 2000-2016 period. As associated causes, shock (39.2%), hemorrhages (33.0%), and hypertensive diseases (26.7%) prevailed with ruptured aneurysms, while hypertensive diseases (29.4%) were associated with unruptured aneurysms. A significant seasonal variation, highest during autumn and followed by in winter, was observed in the overall ruptured and unruptured AAA deaths.CONCLUSIONS:This study highlights the need to accurately document epidemiologic trends related to AAA in Brazil. We demonstrate the burden of AAA on mortality in older individuals, and our results may assist with effective planning of mortality prevention and control in patients with AAA.

Epidemiology of abdominal aortic aneurysms in a Chinese population during introduction of endovascular repair, 1994 to 2013: A retrospective observational study.

The aim of this study was to examine changes in abdominal aortic aneurysm repair and mortality during a period when endovascular aneurysm repair (EVAR) was introduced.Open repair surgery was the mainstay of treatment for abdominal aortic aneurysm (AAA), but EVAR is increasingly utilized. Studies in the Western population have reported improved short-term or postoperative mortality and shorter length of hospital stay with EVAR. However, scant data are available in the Chinese population.We conducted a retrospective observational study using the database of the Hospital Authority, which provides public health care to most of the Hong Kong population. AAA patients admitted to public hospitals for intact repair or rupture from 1994 to 2013 were included in this study. We calculated the incidence of ruptured AAA, annual repair rates according to type of AAA and surgery, as well as death rates (operative and overall short-term). We calculated whether there were significant changes over time and compared short-term mortality between open surgery and EVAR.One thousand eight hundred eighty-five patients were admitted for intact repair and 1306 patients were admitted for AAA rupture, of whom 795 underwent rupture repair. Intact repair rates significantly increased in all age groups (7.3–37.8%, P < .001) over the study period.The incidence of ruptured AAA increased, in all age groups, except in < 64 years old. By 2013, 85% of intact repairs and 55.4% of rupture repair were done by EVAR. Over time, there was a significant decrease in operative mortality for intact repair (16.5 in 1994 to 7.1 in 2013, P = .01) and rupture repair (59.7 in 1994 to 30.8 in 2013, P = .003). Over the same time period, short-term AAA-related deaths decreased by more than half (73% in 1994 to 24% in 2013, P < .001), with a significant decline in all age groups, except < 64 years old. Short-term mortality was significantly lower for EVAR than for open repair (17.2% vs 40.3%, P < .01).Short-term AAA-related deaths have declined likely due to decreased operative mortality and rupture deaths during the period of EVAR introduction and expansion.

Patients' opinions regarding research and management of abdominal aortic aneurysms.

The epidemiology of abdominal aortic aneurysm (AAA) is changing. Outcomes for aortic surgery have improved. Biomarkers of AAA progression are emerging. We recently reported the opinions of international vascular surgery colleagues regarding research and management for AAAs. This study aimed to ascertain a real-world patients' opinion regarding the same questions. We administered a survey to patients with AAAs. We first ascertained their views on the priority topics for research in AAA. Using contemporary epidemiologic and surgical outcome data. We asked their preferences for different aspects of management in the hypothetical scenario where they had been diagnosed with a small (4 cm) AAA and a hypothetical biomarker predicted it to be fast growing. We received 191 responses from patient with AAAs (males 91%, median-age-group 75-79 years). Amongst the topics of research for AAA, the top priorities for research chosen by patients were: "discovering why AAA develops in a person" and "discovering new medications that can make an AAA shrink back to normal size". In the hypothetical scenario, 42% of patients would prefer to have surgery early, while they are younger and fitter. Fifty-two percent would follow the surgeon's recommendation as to whether to have early surgery or not. A high proportion of respondents would likely consider taking part in a clinical trial to test if early surgery in such a scenario will be beneficial. The results represent a snapshot of patient's views in terms of priorities for AAA research. We further demonstrate how patient's opinions can signpost the potential path for biomarker research to impact clinical practice.

The Experience of Patients During the Clinical Management Pathway of Abdominal Aortic Aneurysms at a NHS Trust.

Background:The epidemiology of abdominal aortic aneurysm (AAA) is changing. Outcomes for aortic surgery have improved. However, the accepted guideline for the management of AAAs has remained unchanged over the last 2 decades. We aimed to gain insight into the patients’ experience while they are managed under the traditional clinical pathway.Method:With the help of a patient focus group, we designed a survey to assess the patients’ perception of the disease and their experience during different stages of the AAA clinical care pathway (surveillance, perioperative care, postoperative follow-up). An invitation to participate in the survey was sent to all patients with AAA who were receiving care at the Oxford Regional Vascular Services Unit, part of the Oxford University Hospitals NHS Trust.Results:We received 194 responses from patients with AAA. One hundred seventy-seven were male, with a median age of 75 to 79 years. Just over a third had undergone surgery already, and the remaining 63% were either in surveillance or awaiting surgery. Their experience during the AAA management pathway was mostly positive. Of the issues that were most important to them in terms of their medical care, the provision of explanation and regularity of monitoring stood out as the most common considerations.Conclusion:Patients are generally satisfied with the care they received, but there is room for improvement. They have also highlighted key areas that are most important to them in terms of their medical care. These should guide the future direction for quality improvement and research.

Screening for Abdominal Aortic Aneurysm in 65-Year-old Men Remains Cost-effective with Contemporary Epidemiology and Management

The epidemiology and management of abdominal aortic aneurysms (AAA) has changed significantly, with lower prevalence, increased longevity of patients, increased use of endovascular aneurysm repair (EVAR), and improved outcome. The clinical and health economic effectiveness of one-time screening of 65-year-old men was assessed within this context. One-time ultrasound screening of 65-year-old men (invited) versus no screening (control) was analysed in a Markov model. Data on the natural course of AAA (risk of repair and rupture) was based on randomised controlled trials. Screening detected AAA prevalence (1.7%), surgical management (50% EVAR), repair outcome, costs, and long-term survival were based on contemporary population-based data. Incremental cost-efficiency ratios (ICER), absolute and relative risk reduction for death from AAA (ARR, RRR), numbers needed to screen (NNS), and life-years gained were calculated. Annual discounting was 3.5%. In base case at 13-years follow-up the ICER was €14,706 per incremental quality-adjusted life-year (QALY); ARR was 15.1 per 10,000 invited, NNS was 530, and QALYs gained were 56.5 per 10,000 invited. RRR was 42% (from 0.36% in control to 0.21% in invited). In a lifetime analysis the ICER of screening decreased to €7,570/QALY. The parameters with highest impact on the cost-efficiency of screening in the sensitivity analysis were the prevalence of AAA (threshold value <0.5%) and degree of incidental detection in the control cohort. In the face of recent changes in the management and epidemiology of AAA, screening men for AAA remains cost-effective and delivers significant clinical impact.

Screening for Abdominal Aortic Aneurysm in 65-Year-old Men Remains Cost-effective with Contemporary Epidemiology and Management

The epidemiology and management of abdominal aortic aneurysms (AAA) has changed significantly, with lower prevalence, increased longevity of patients, increased use of endovascular aneurysm repair (EVAR), and improved outcome. The clinical and health economic effectiveness of one-time screening of 65-year-old men was assessed within this context. One-time ultrasound screening of 65-year-old men (invited) versus no screening (control) was analysed in a Markov model. Data on the natural course of AAA (risk of repair and rupture) was based on randomised controlled trials. Screening detected AAA prevalence (1.7%), surgical management (50% EVAR), repair outcome, costs, and long-term survival were based on contemporary population-based data. Incremental cost-efficiency ratios (ICER), absolute and relative risk reduction for death from AAA (ARR, RRR), numbers needed to screen (NNS), and life-years gained were calculated. Annual discounting was 3.5%. In base case at 13-years follow-up the ICER was €14,706 per incremental quality-adjusted life-year (QALY); ARR was 15.1 per 10,000 invited, NNS was 530, and QALYs gained were 56.5 per 10,000 invited. RRR was 42% (from 0.36% in control to 0.21% in invited). In a lifetime analysis the ICER of screening decreased to €7,570/QALY. The parameters with highest impact on the cost-efficiency of screening in the sensitivity analysis were the prevalence of AAA (threshold value <0.5%) and degree of incidental detection in the control cohort. In the face of recent changes in the management and epidemiology of AAA, screening men for AAA remains cost-effective and delivers significant clinical impact.

Prevalence and Trends of the Abdominal Aortic Aneurysms Epidemic in General Population - A Meta-Analysis

ObjectiveTo conduct a meta-analysis assessing the prevalence and trends of the abdominal aortic aneurysms (AAA) epidemic in general population.MethodStudies that reported prevalence rates of AAA from the general population were identified through MEDLINE, EMBASE, Web of Science, and reference lists for the period between 1988 and 2013. Studies were included if they reported prevalence rates of AAA in general population from the community. In stratified analyses possible sources of bias, including areas difference, age, gender and diameter of aneurysms were examined. Publication bias was assessed with Egger's test method.Results56 studies were identified. The overall pooled prevalence of AAA was 4.8% (4.3%, 5.3%). Stratified analyses showed the following results, areas difference: America 2.2% (2.2%, 2.2%), Europe 2.5% (2.4%, 2.5%), Australia 6.7% (6.5%, 7.0%), Asia 0.5% (0.3%, 0.7%); gender difference: male 6.0% (5.3%, 6.7%), female 1.6% (1.2%, 1.9%); age difference: 55–64years 1.3% (1.2%, 1.5%), 65–74 years 2.8% (2.7%, 2.9%), 75–84 years1.2%(1.1%, 1.3%), ≥85years0.6% (0.4%, 0.7%); aortic diameters difference: 30–39 mm, 3.3% (2.8%, 3.9%), 40–49 mm,0.7% (0.4%,1.0%), ≥50 mm, 0.4% (0.3%, 0.5%). The prevalence of AAA has decreased in Europe from 1988 to 2013. Hypertension, smoking, coronary artery disease, dyslipidemia, respiratory disease, cerebrovascular disease, claudication and renal insufficiency were risk factors for AAA in Europe.ConclusionAAA is common in general population. The prevalence of AAA is higher in Australia than America and Europe. The pooled prevalence in western countries is higher than the Asia. Future research requires a larger database on the epidemiology of AAA in general population.

Changes in Abdominal Aortic Aneurysm Rupture and Short-Term Mortality, 1995–2008

To examine the modern epidemiology of abdominal aortic aneurysm (AAA) rupture and short-term AAA-related mortality after the introduction of endovascular aneurysm repair (EVAR). Previous epidemiologic studies have demonstrated stable rates of AAA repair, repair mortality, and AAA rupture. Recently, EVAR has been introduced as a less invasive treatment method, and its use has expanded to more than 75% of elective AAA repairs. We identified Medicare beneficiaries undergoing AAA repair and those hospitalized with a ruptured AAA during the period 1995 to 2008 and calculated standardized annual rates of AAA-related deaths due to either elective repair or rupture. A total of 338,278 patients underwent intact AAA repair during the study period. There were 69,653 patients with AAA rupture, of whom 47,524 underwent repair. Intact repair rates increased substantially in those older than 80 years (57.7-92.3 per 100,000, P < 0.001) but decreased in those 65 to 74 years old (81.8-68.9, P < 0.001). A decline in ruptures with and without repair was seen in all age groups. By 2008, 77% of all intact repairs and 31% of all rupture repairs were performed with EVAR (P < 0.001). Operative mortality declined during the study period for both intact (4.9%-2.4%, P < 0.001) and ruptured (44.1%-36.3%, P < 0.001) AAA repair. Short-term AAA-related deaths decreased by more than half (26.1-12.1 per 100,000, P < 0.001), with the greatest decline occurring in those older than 80 years (53.7-27.3, P < 0.001). A recent decline in AAA rupture and short-term AAA-related mortality is demonstrated and likely related in part to the introduction and expansion of EVAR. This is due to decreased deaths from ruptures (with and without repair) and decreased mortality with intact repairs, particularly in patients older than 80 years.

Changing Epidemiology of Abdominal Aortic Aneurysms in England and Wales

Background— Recent studies from Australia, New Zealand, and Sweden have reported declines in abdominal aortic aneurysm (AAA) incidence, prevalence, and mortality. This finding may have important implications for screening programs. This study determined trends in AAA incidence and mortality in England and Wales. Methods and Results— Cause-specific mortality data for England and Wales were obtained from UK Office for National Statistics, and hospital admissions and procedures data for England were obtained from Hospital Episode Statistics from 2001 to 2009. Poisson regression models were constructed to estimate the relative change over time. Age-standardized rates for AAA mortality in England and Wales fell significantly by 35.7% from 2001 to 2009, which was largely due to a 35.3% drop in age-standardized ruptured AAA deaths. During the same period, ruptured AAA admissions and emergency AAA repairs in England declined by 29.3% and 35.5%, respectively. In contrast, nonruptured AAA admissions remained static, and nonemergency AAA repairs increased by 17.2%. The average ages for hospital admissions for nonruptured AAAs and ruptured AAAs increased by 0.19 years of age per annum ( P &lt;0.001) and 0.09 years of age per annum ( P &lt;0.001), respectively. Nonruptured AAA admissions increased by 21.4% in age band 75 years or more but declined by 11.7% in ages &lt;75 years. Conclusions— AAA mortality, ruptured AAA admission, and emergency AAA repair have declined in England and Wales. However, nonruptured AAA admission has remained steady, with an increasing rate in older population offsetting a decreasing rate in younger population. This suggests a shift in AAA presentation to the older population. Present screening strategies may need reassessment to include consideration for increasing the age at which to screen men for AAAs.

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.

Outcome after abdominal aortic aneurysm repair in Sweden 1994–2005

The aim was to study the epidemiology of abdominal aortic aneurysm (AAA) repair in Sweden. Primary AAA repairs registered in the Swedish Vascular Registry between 1994 and 2005 were studied. Mortality data were obtained from the national population registry, and age- and sex-specific populations for each calendar year from Statistics Sweden. Some 10,691 primary AAA repairs were identified. In the population aged 60 years or over the incidence of intact AAA repair increased from 27.0 per 100,000 in 1994-1999 to 28.8 per 100,000 in 2000-2005 (P = 0.006), while the incidence of surgery for ruptured AAA (rAAA) remained stable (13.8 versus 14.1 per 100,000; P = 0.595). Open repair with a bifurcated graft decreased, whereas endovascular repair (EVAR) increased to 35.0 per cent of intact AAA and 10.3 per cent of rAAA procedures in 2005. Patients who had EVAR were older than those undergoing open repair (74.1 versus 71.9 years; P < 0.001). The 30-day mortality rate decreased over time for intact and ruptured aneurysm operations (P = 0.001). Age, female sex and open repair (compared with EVAR) were independently associated with a higher 30-day mortality rate in a logistic regression model. The introduction of EVAR was associated with an increasing incidence of intact AAA repair, whereas the rate of rAAA was stable. Perioperative mortality rates decreased over time.

Epidemiology of Aortic Aneurysm Repair in the United States from 1993 to 2003

The epidemiology of abdominal aortic aneurysm (AAA) disease has been well described over the preceding 50 years. This disease primarily affects elderly males with smoking, hypertension, and a positive family history contributing to an increased risk of aneurysm formation. The aging population as well as increased screening in high-risk populations has led some to suggest that the incidence of AAAs is increasing. The National Inpatient Sample (1993-2003), a national representative database, was used in this study to determine trends in mortality following AAA repair in the United States. In addition, the impact of the introduction of less invasive endovascular AAA repair was assessed. Overall rates of treated unruptured and ruptured AAAs remained stable (unruptured 12 to 15/100,000; ruptured 1 to 3/100,000). In 2003, 42.7% of unruptured and 8.8% of ruptured AAAs were repaired through an endovascular approach. Inhospital mortality following unruptured AAA repair continues to decline for open repair (5.3% to 4.7%, P = 0.007). Mortality after elective endovascular AAA repair also has statistically decreased (2.1% to 1.0%, P = 0.024) and remains lower than open repair. Mortality rates for ruptured AAAs following repair remain high (open: 46.5% to 40.7%, P = 0.01; endovascular: 40.0% to 35.3%, P = 0.823). These data suggest that the numbers of patients undergoing elective AAA repair have remained relatively stable despite the introduction of less invasive technology. A shift in the treatment paradigm is occurring with a higher percentage of patients subjected to elective endovascular AAA repair compared to open repair. This shift, at least in the short term, appears justified as the mortality in patients undergoing elective endovascular AAA repair is significantly reduced compared to patients undergoing open AAA repair.

Epidemiology of abdominal aortic aneurysm in an Asian population.

Abdominal aortic aneurysms (AAA) are common in the Caucasian population. Apart from reported differences in the occurrence of AAA in the black and white populations, there are few studies on the incidence of AAA in the Asian population. A prospective database of all patients with AAA seen between 1996 and 1999, in the South-East Asian state of Sarawak in Borneo Island, was analysed. The demographic data included patient's age, sex, ethnic group, date of diagnosis, comorbidities, presentations and treatment outcomes. These were compared with the state population's demographic statistics. Diagnoses of AAA were made in 123 patients during the study period. The male to female ratio was 3.5 : 1. The age range was 39-88 years with a median age of 70 years. Four patients were younger than 55 years. The incidence rate for the at-risk male population older than 50 years was 25.6/100,000. The incidence rate reached 78.3/100,000 for males older than 70 years. The incidence rate for females older than 50 years was 7.6/100,000 and for those older than 70 years it was 18.7/100,000. All races were affected. Smoking, hypertension or respiratory disorders were present in more than 40% of the patients. Half of the patients underwent surgical repair. This study shows that AAA in this Asian population is not uncommon and the incidence is comparable to the Western world.

Epidemiology of abdominal aortic aneurysms in the Asian community.

Studies relating to the ethnic origin of patients with an abdominal aortic aneurysm (AAA) are few and are mainly concerned with the differences between black and white Americans. The purpose of this study was to determine whether the incidence of AAA among the Asian population of Bradford is different from that in the Caucasian population. A retrospective study of patients with an AAA was carried out between 1990 and 1997 using data collected by the Patient Administrative Service, personal databases of the vascular consultants and theatre records. Information about the ethnic composition of the population of Bradford was obtained from the 1991 national census. Demographic data, including ethnic origin and clinical details, were obtained from patient notes. Two hundred and thirty-three patients with an AAA were identified during the study interval. The Asian population comprised 14.0 per cent of the total population of Bradford. Twenty-eight AAAs would be expected per year. All of the aneurysms identified occurred in the Caucasian population and none in the Asian community. These early results suggest that AAA is rare among the Asian population.

Epidemiology of abdominal aortic aneurysms.

Abdominal aortic aneurysms are responsible for a substantial public health burden in developed countries. In 1991, abdominal aneurysm was cited as the primary or secondary cause of 12,711 deaths in the United States (1). Aortic aneurysms of unspecified site, many of which were probably abdominal, were cited for a further 4,108 deaths. It has been estimated that abdominal aneurysms cause 1-2 percent of all deaths among men over the age of 65 in the United States (2). In Canada, vital statistics data show that there are approximately 1,000 deaths attributable to abdominal aneurysm annually (3). Since abdominal aneurysms often escape clinical detection, these vital statistics data probably underestimate the true magnitude of mortality related to abdominal aneurysm. Abdominal aneurysms are also responsible for considerable morbidity and health care costs. In the United States in 1992, abdominal aneurysm was cited as the primary diagnosis for approximately 53,000 hospital discharges, and there were approximately 40,000 surgical operations for this aneurysm (1). In Canada in 1990, abdominal aneurysm was cited as the primary diagnosis for 5,638 hospitalizations (3). Mortality and morbidity related to abdominal aneurysm has increased substantially in recent decades. In the United States, the number of deaths due to abdominal aneurysm increased by almost 20 percent between 1979 and 1991, and the number of related hospitalizations more than doubled (1). In England and Wales, the number of deaths due to abdominal aneurysm increased by 53 percent between 1974 and 1984 (4). In Canada, the number of hospitalReceived for publication May 26, 1998, and accepted for publication July 6, 1999. Abbreviations: HDL, high density lipoprotein; LDL, low density lipoprotein; VLDL, very low density lipoprotein. 1 Epidemiology Unit, Public Health Branch, Manitoba Health, Winnipeg, Manitoba, Canada. 2 Department of Community Health Sciences, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada. 3 Department of Medical Microbiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada. Reprint requests to Dr. James F. Blanchard, Manitoba Health, 4058-300 Carlton Street, Winnipeg, Manitoba R3B 3M9, Canada. izations related to abdominal aneurysm increased almost fourfold between 1970 and 1990 (3). Similarly, in Western Australia, the number of surgical operations for abdominal aneurysm more than doubled between the early 1970s and the early 1980s (5). Despite the public health importance of abdominal aneurysms, much is still unknown with respect to their etiology. Historically, they have been considered simply a manifestation of atherosclerosis (6-8). However, this conventional theory has come under increasing challenge in the past two decades. Whereas aortic atherosclerosis is common, a relatively small proportion of persons develop aneurysmal disease. Furthermore, epidemiologic, genetic, and biochemical research indicates that the etiology of abdominal aneurysm is distinct from atherosclerosis per se. The first part of this review provides an overview of the definition, pathophysiology, and natural history of abdominal aneurysm. In the second part, descriptive and analytic epidemiologic studies are reviewed with an emphasis on their implications for etiology.

Screening for abdominal aortic aneurysm: A computer assisted cost-utility analysis

To evaluate the effects of introducing routine ultrasonic screening for the identification and elective surgical treatment of abdominal aortic aneurysms (AAA) at high risk of rupture in the U.K. population of men aged 65-74 years. A computer assisted simulation of an AAA screening programme. The simulation incorporated assumptions gleaned from the literature about the epidemiology of AAA and the costs of screening. In addition, up-to-date costings based on recent Manchester (U.K.) vascular surgery experience are used. A dialogue between National Health Service commissioners and providers to explore the feasibility and desirability of introducing AAA screening. CHIEF OUTCOME MEASURE: Cost per quality adjusted life year (QALY) gained. The absolute cost (circa 1992/3) per QALY gained from screening for and treating aneurysms of > or = 6 cm in diameter of pounds 1500 (benefit not discounted). Offsetting current treatment costs of ruptured aneurysms gives a net additional cost per QALY of pounds 1300. Screening and treating aneurysms of > or = 5 cm leads to a cost per QALY gained exceeding pounds 20000. The findings are robust under sensitivity analysis. Routine screening for AAAs of size > or = 6 cm compares favourably in terms of cost per QALY gained with services such as breast and cervical cancer screening.

Epidemiology of abdominal aortic aneurysm: The effect of differing definitions

There have been several published definitions for abdominal aortic aneurysm (AAA), however, it is not known how different definitions affect what is reported. This paper presents an evaluation of three definitions taken from the literature on (a) aneurysm frequency, (b) prevalence rate and (c) prevalence ratio from an ongoing case-control study evaluating whether male siblings of patients with known AAA have a higher prevalence of aneurysms compared to a control group. Depending on the definition used, the frequency of AAA could vary from a low of five to a high of 23; the prevalence of AAA in siblings could range from 2.1 to 18.8. Changing definitions alters the prevalence ratio (risk of disease) in both magnitude and direction. On the one hand, male sibling of affected patients are at approximately one and a half times (1.6) greater risk of having an AAA compared to controls, whereas using a different definition they are at less than half the risk (0.3).