Influence of diagnostic criteria on the prevalence of abdominal aortic aneurysm

Purpose: We studied the prevalence of abdominal aortic aneurysm (AAA) in a population with high incidences of cardiovascular diseases and analyzed how the prevalence varies according to methodology and criteria. Methods. All men and women aged 65 to 75 years who lived in the Norsjo muni cipality in northern Sweden were invited to undergo an ultrasound scanning (US) examination. Those with an aortic diameter of 28 min or more or with p oor visibility on US were examined with computed tomography scanning (CT). Various recommended AAA definitions, two diagnostic methods (US and CT), an d two diameters (maximum and anteroposterior) were analyzed. Results. Of 555 people invited to participate in the study, 504 accepted (2 48 men and 256 women; 91%). Eight subjects had undergone surgery for an AAA . Ninety-two subjects underwent CT. The mean maximum infrarenal aortic diam eter was 24.6 mm (by means of US). Depending on diagnostic criteria, the AA A prevalence was 3.6% to 16.9% in men and 0.8% to 9.4% in women. Depending on which previous study was used as a comparison and the definition of AAA and diagnostic technique used, the prevalence in this study was 1.3 to 4.0 times higher for men and 2.0 to 5.8 times higher for women. Conclusion: In a region in which residents have a high risk for cardiovascu lar disease, we found the highest prevalence of AAA ever reported within a population. The prevalence highly depends on methodology and diagnostic cri teria, with a 10-fold variation. Detailed defined criteria are necessary to permit comparisons between studies: the number of individuals who have und ergone surgery for AAA and whether they are included, the prevalence in 5- and 10-year age intervals, attendance rate, visibility, which diamcter(s) i s measured, and the prevalences with as many as possible of the four descri bed definitions of AAA. The etiology of the high prevalence of AAA in this population needs to be investigated further.