O-198 - OPTIMIZING POPULATION-BASED AAA SCREENING OF 65-YO MEN BY EXPLORING RISK FACTOR BASED TARGETED SCREENING STRATEGIES - IN LIGHT OF DECLINING PREVALENCE.

TOPIC:
Abdominal Aortic Aneurysms
AUTHORS:
Söderberg P. (Department of Surgical Sciences, Vascular Surgery, Uppsala University, Uppsala, Sweden ~ Uppsala ~ Sweden) , Wanhainen A. (Department of Surgical Sciences, Vascular Surgery, Uppsala University, Uppsala, Sweden ~ Uppsala ~ Sweden) , Svensjö S. (Department of Surgical Sciences, Vascular Surgery, Uppsala University, Uppsala, Sweden ~ Uppsala ~ Sweden)
Introduction:
The prevalence of AAA has declined over the past decades and contemporary studies demonstrate prevalence rates of 1.3-1.5% (1, 2) among 65-yo men, in contrast to historical rates of 4.9-7.2% (3, 4) in the large scale screening RCTs conducted in the 90s and early 00s. Cost-efficiency (5) can be demonstrated for screening programs with even lower rates, but the clinical legitimacy of general AAA screening of 65-yo men can be questioned with falling prevalence rates. This study analyses risk factor data among large cohorts of 65-yo men screened in the Swedish population-based general AAA screening program - with the aim of exploring selective targeting screening strategies to reach men with the highest risk of having an AAA.
Methods:
In previous studies (6), all men attending AAA screening in four neighboring counties in Sweden 2006-2010 were asked to complete a health questionnaire on smoking habits, medical history and heredity. Smoking habits were divided into never-, former or current smoker, and when possible stratified according to duration of smoking. Additional risk factors associated with having an AAA were identified by a multivariate logistic analysis. The sensitivity and specificity of different targeted screening strategies - with targeted sub-populations defined by combining various risk factors significantly associated with AAA - were explored. Receiver operating characteristic (ROC) was used to identify the optimal cut off value between sensitivity and specificity.
Results:
With a high attendance rate for AAA screening of >80%, a total of 16232 men were included. 2129 men were current smokers, 10308 were wither current- or former smokers and 3795 were never smokers. A total of 236 (1.5%) AAAs were detected among all screened men. Duration of smoking, and/or coronary artery disease proved the most useful for constructing a targeted screening strategy when optimizing sensitivity in relation to specificity, using the Youden index point as reference in the ROC analysis. At the Youden index point, corresponding to targeting men having smoked 30 years or more or/and with a history of coronary artery disease, 70 % of all AAAs could be detected by screening only 30 % of all 65-yo men. Improving sensitivity by sacrificing specificity, a strategy of targeting all men that have smoked 10 years or more, resulted in detecting 84% of all AAAs by screening 55% of the general population. A prevalence of 2.2% for AAA was noted in this targeted group, and in the not targeted partition a prevalence of 0,5% was noted. Adding complexity by applying multiple risk factors in selection; targeting all men that have smoked 1 year or more and/or having coronary artery disease, resulted in detecting 87 % of all AAAs by screening 64% of the general population. Exploring a cruder, simplified strategy of smoking-based targeted screening, targeting ever smokers resulted in detecting 85 % of all AAAs by targeting 61% of the general population.
Conclusion:
The prevalence for AAA in men is dramatically lower today than in the large RCTs conducted in the 90s and this raises concerns on the clinical legitimacy of today's general population-based AAA screening programs. Targeted high-risk screening, with smoking history as the most important factor to consider, may be a safe alternative to increase the yield of AAA screening programs.
References:
1. Oliver-Williams C, Sweeting MJ, Turton G, Parkin D, Cooper D, Rodd C, et al. Lessons learned about prevalence and growth rates of abdominal aortic aneurysms from a 25-year ultrasound population screening programme. Br J Surg. 2018;105(1):68-74. 2. Wanhainen A, Hultgren R, Linne A, Holst J, Gottsater A, Langenskiold M, et al. Outcome of the Swedish Nationwide Abdominal Aortic Aneurysm Screening Program. Circulation. 2016;134(16):1141-8. 3. Ashton HA, Buxton MJ, Day NE, Kim LG, Marteau TM, Scott RA, et al. The Multicentre Aneurysm Screening Study (MASS) into the effect of abdominal aortic aneurysm screening on mortality in men: a randomised controlled trial. Lancet. 2002;360(9345):1531-9. 4. Norman PE, Jamrozik K, Lawrence-Brown MM, Le MT, Spencer CA, Tuohy RJ, et al. Population based randomised controlled trial on impact of screening on mortality from abdominal aortic aneurysm. BMJ. 2004;329(7477):1259. 5. Svensjo S, Mani K, Bjorck M, Lundkvist J, Wanhainen A. Screening for abdominal aortic aneurysm in 65-year-old men remains cost-effective with contemporary epidemiology and management. Eur J Vasc Endovasc Surg. 2014;47(4):357-65. 6. Svensjo S, Bjorck M, Wanhainen A. Editor's choice: five-year outcomes in men screened for abdominal aortic aneurysm at 65 years of age: a population-based cohort study. Eur J Vasc Endovasc Surg. 2014;47(1):37-44.
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