Screening for abdominal aortic aneurysms (AAAs) in elderly men with ultrasound is regarded as an established method to reduce AAA related mortality. Initial studies have reported a reduction of AAA related mortality of more than 40% in screening programs.
1
, 2
, 3
, 4
In the past 5 years, however, further epidemiological studies have indicated a reduction in the incidence of AAA. Current data in UK and Sweden have demonstrated an incidence of almost half that seen in screening trials, it is but still regarded as cost efficient.5
, 6
Earlier studies of the prevalence of AAA in men of Asian origin showed a low incidence and therefore there is uncertainty about cost effectiveness of screening Asian patients.7
, 8
In this issue of the European Journal of Vascular and Endovascular Surgery, Dr. Li and colleagues9
report independent predictors for AAA and also the incidence of AAA in Chinese patients.The patients studied consisted of 1582 consecutive patients with atherosclerotic risk factors undergoing coronary angiography for coronary artery disease (CAD). Previous studies in male patients with CAD have demonstrated an incidence of up to 9.5% for AAA.
10
The overall incidence in the current study (men and women) was 1.6% and increased to 2.9% in male patients aged over 65 years. Data on incidence reported were thus similar to recent studies from Sweden and UK. These data suggest the hypothesis that the prevalence of AAA in the Chinese may be lower than expected, even in the presence of risk factors such as CAD. The pathogenesis of AAA and CAD is different but risk factors such as advanced age, smoking, and hypertension all promote both atherosclerosis and aneurysmal degeneration. The change in epidemiology in Europe and the USA is probably due to reduced smoking and improved treatment of risk factors such as hypertension and may also be relevant to the current study.The absolute diameters of the aorta might differ between Caucasians and Asians because of differences in body size. A study measured the average aortic diameter of Chinese patients to be 14.6 mm, which was significantly smaller than Caucasians.
11
In the current study, the average aortic diameter was 18.6 mm in patients without AAA and is similar to data from Sweden and the ADAM study where the non-aneurysmal aortic diameter was 19 and 20 mm respectively.5
, 12
A method to further define the aortic size in relation to body size is to calculate the aortic size index (ASI). This is performed by dividing the aortic diameter by the body size area (BSA); for example, ASI = aneurysm diameter (cm)/BSA (m2). This has been performed in women, and the aneurysm diameter indexed to body size is the most important determinant of rupture for women.13
Aortic root diameter was also investigated in the study and a diameter >30 mm was an independent predictor of AAA. An official cutoff for the definition of aortic dilatation has not been determined because of the variability of this measure. Also in this location, the ASI might be used which takes into account the body surface area, thus minimising the classification of normal aorta as pathologically dilated and vice versa.
With the relatively low incidence of AAA in the current study despite the presence of several risk factors in the study cohort questions arise about cost effectiveness of a more generalised screening program. Patients studied were selected from an in hospital cohort and it is difficult to extrapolate the findings to a larger population. The data, however, support a relatively low incidence of AAA in screened Chinese patients with atherosclerotic risk factors. Further larger scale population based studies are necessary to further define the true incidence of AAA in Chinese patients.
References
- Influence of screening on the incidence of ruptured abdominal aortic aneurysm: 5-year results of a randomized controlled study.Br J Surg. 1995; 82: 1066-1070
- 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: 1531-1539
- Population based randomised controlled trial on impact of screening on mortality from abdominal aortic aneurysm.BMJ. 2004; 329: 1259-1262
- Screening for abdominal aortic aneurysms: single centre randomised controlled trial.BMJ. 2005; 330: 750-754
- Low prevalence of abdominal aortic aneurysm among 65-year-old Swedish men indicates a change in the epidemiology of the disease.Circulation. 2011; 124: 1118-1123
- First-year results of a national abdominal aortic aneurysm screening programme in a single centre.Br J Surg. 2012; 99: 73-77
- Epidemiology of abdominal aortic aneurysms in the Asian community.Br J Surg. 2001; 88: 382-384
- Should Asian men be included in abdominal aortic aneurysm screening programmes?.Eur J Vasc Endovasc Surg. 2009; 38: 748-749
- Predictors associated with increased prevalence of abdominal aortic aneurysm in Chinese patients with atherosclerotic risk factors.Eur J Vasc Endovasc Surg. 2017; 54: 43-49
- The prevalence of abdominal aortic aneurysm is consistently high among patients with coronary artery disease.J Vasc Surg. 2015; 62: 232-240
- Abdominal aortic diameter and vascular atherosclerosis: the Multi-Ethnic Study of Atherosclerosis.Eur J Vasc Endovasc Surg. 2011; 41: 481-487
- The aneurysm detection and management study screening program: validation cohort and final results. Aneurysm Detection and Management Veterans Affairs Cooperative Study Investigators.Arch Intern Med. 2000; 160: 1425-1430
- Relative importance of aneurysm diameter and body size for predicting abdominal aortic aneurysm rupture in men and women.J Vasc Surg. 2014; 59: 1209-1216
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Published online: June 13, 2017
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- Predictors Associated With Increased Prevalence of Abdominal Aortic Aneurysm in Chinese Patients with Atherosclerotic Risk FactorsEuropean Journal of Vascular and Endovascular SurgeryVol. 54Issue 1
- PreviewEpidemiological screening studies have demonstrated that the prevalence of abdominal aortic aneurysm (AAA) of Asian origin appears to be low and so increases uncertainty about the cost effectiveness of screening for AAAs in Chinese people. Some studies have demonstrated a higher prevalence of AAA in patients with atherosclerotic risk factors. The purpose of the study was to determine the prevalence of AAA and to explore the high risk group of AAA in Chinese patients with atherosclerotic risk factors.
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