Selecting subjects for ultrasonographic screening for aneurysms of the abdominal aorta: Four different strategies

Abstract

Background. We studied whether the effectiveness of ultrasound screening for abdominal aortic aneurysms could be increased by preselecting high-risk subjects, based on the presence of risk indicators for the disease. Methods. In a population-based screening programme for abdominal aortic aneurysms among 5328 subjects living in Rotterdam, The Netherlands, we studied four different strategies to select subjects for ultrasound screening of the abdominal aorta, based on risk indicators for abdominal aortic aneurysm disease. Risk indicaters used in each strategy were entered in a logistic regression model to predict the probability of an individual having an abdominal aortic aneurysm. Using several cutoff values for the probability of a subject having an aneurysm for each strategy we estimated the proportion of subjects that should be referred for ultrasound screening and the proportion of aneurysms that would be diagnosed by each strategy (sensitivity). Results. When a probability of 1.5% of having an aneurysm is chosen as the cutoff point above which ultrasound screening is indicated, the proportion of subjects that would be referred for screening ranged from 36% (first strategy) to approximately 50% (other strategies), while 80% (first strategy) to approximately 94% (other three strategies) of all aneurysms would be detected. Conclusion. Effectiveness in screening for abdominal aortic aneurysms can be increased by selecting subjects by means of a short medical questionnaire, filled out by the screening candidates, including questions on medical history.