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.