Prevalence of abdominal aortic aneurysm in emergency department patients with high-risk symptoms

Abstract

Study objectives: The prevalence of abdominal aortic aneurysm (AAA) has been measured in a number of populations, suggesting that the prevalence is anywhere from 3% to 11% of those populations studied. Men between the ages of 65 and 74 years have a prevalence rate of 5.4%, men and women between the ages of 65 and 80 years have a prevalence rate of 4.3%, and hypertensive patients with peripheral vascular disease have a prevalence rate of 9.6%. Although the classic triad of hypotension, pulsatile abdominal mass, and abdominal pain occurs infrequently, there is a lack of reliable information on the prevalence of this disease in an emergency department (ED) population with symptoms that could relate to aortic aneurysms. The purpose of this pilot study is to gather prevalence data on AAA dilatation in patients at risk for disease in an ED setting. Methods: This was a convenience sample of patients presenting during times when an emergency physician trained in ultrasonography was available. Any patient 50 years or older who had 1 of the 6 symptoms (abdominal pain, back pain, flank pain, groin pain, syncope, or hypotension) was considered for the study. Abdominal aortas were measured in the longitudinal plane and transverse plane using a Hitachi EUB 405 Ultrasound machine with a 3.5-MHz curvilinear probe. Informed consent was obtained from the patient. Images were obtained above the level of the bifurcation but below the level of the superior mesenteric artery. Because adequate previous studies have demonstrated the accuracy of trained emergency physicians in interpreting these studies, confirmatory examinations were not required as part of this study. Diameters greater than 3 cm were considered aneurysmal. Images were saved and reviewed by one of the investigators blinded to outcome. Data were analyzed using simple descriptive statistics. Results: Ninety-seven patients were entered in the study, of whom 57% were male patients, 66% had a history of hypertension, and 38% used tobacco. The mean age was 67.4±10.8 years. The most common symptom was abdominal pain (40.6%), followed by back pain and hypotension, each at 21.9%. The mean maximal aortic diameter was 2.0±0.7 cm. There were 5 patients with a maximal aortic diameter of 3 cm or more, resulting in a prevalence of 5.15% (95% confidence interval [CI] 0.8% to 9.6%). Two patients had a maximal diameter of greater than 5 cm (2.1%; 95% CI 0.4% to 8%). The outcome of the 2 patients with a maximal diameter greater than 5 cm was satisfactory. One patient had a known history of AAA status postrepair was admitted to vascular surgery and discharged 2 days later without intervention. The other patient had a newly diagnosed AAA, which vascular surgery evaluated and discharged from the ED for outpatient follow-up. No patient with aneurysmal dilation of the aorta was found to be ruptured. Conclusion: The prevalence of AAA in an ED population at risk with symptoms that could be referable to the aorta is in the range of that which has been described in other populations. Although the incidence of symptomatic aortic aneurysms is lower, the utility of screening of patients at risk warrants further study.