Ultrasonic screening for the detection of abdominal aortic aneurysms

Detection of aortic aneurysms before they rupture is imperative if the mortality rate from this disease is to be reduced. Although large aneurysms frequently are palpable, small aneurysms--especially in obese patients--are seldom recognized on physical examination. Ultrasound, which is noninvasive, relatively inexpensive, and nearly 100 per cent accurate in identifying the presence or absence of aneurysms, is well suited to screening. In high-risk populations (patients over the age of 50 with coronary artery or peripheral vascular disease), ultrasonic screening is probably cost-effective.     

A screening program to identify risk factors for abdominal aortic aneurysms.

BACKGROUND: We aimed to explore the feasibility of a nurse-supervised aneurysm screening program to identify any independent risk factors for abdominal aortic aneurysm (AAA) formation in high-risk patients. METHODS: We conducted a prospective observational study of 90 male patients in a university- affiliated hospital in southern Ontario. The patients were prospectively evaluated and all underwent abdominal ultrasonography, with the main outcome measure being detection of an AAA. RESULTS: AAAs were identified in 18 patients (20%) and had a mean diameter of 3.6 (range 2.8-6.0) cm. A separate analysis was performed to identify risk factors for the presence of an aneurysm. The presence of carotid artery disease proved to be the only statistically significant independent predictor of the presence of AAA (odds ratio 2.23, 95% confidence interval 1.76-2.56). CONCLUSIONS: This study confirms the feasibility of a nurse-supervised AAA screening program, and on the basis of these results we recommend ultrasonographic screening for AAA in patients with a history of carotid artery disease.     

The case against a national screening programme for aortic aneurysms.

This review examines the assumptions underlying the calls for a national screening programme for aneurysms. It concludes that on the basis of published evidence, many of the necessary criteria for any putative screening programme are not met for this disease. Although the disease is an important cause of death, and a screening method is available, we lack basic knowledge about the natural history of the disease, especially small aneurysms, and about the cost-effectiveness of a screening programme. In particular, the treatment is an operation which, nationwide, carries a high mortality and is likely to be unacceptable to many patients. The consequences of such a programme would be to diagnose many small aneurysms, for which the best treatment remains unclear, and which will engender much unnecessary anxiety among patients so diagnosed.     

A comparison between the short term and long term benefits of screening for abdominal aortic aneurysms from the Huntingdon Aneurysm screening programme.

BACKGROUND: The UK Multicentre Aneurysm Screening Study (MASS) showed a 44% reduction in AAA-related mortality after 4 years and predicted an increased number of deaths prevented in the longer term. We aim to compare the 5 and 13 years benefit from aneurysm screening in the Huntingdon Aneurysm screening programme. METHODS: Incidence and mortality of ruptured AAA (RAAA) after 5 and 13 years of screening in a population based aneurysm screening program. RESULTS: Five years of screening resulted in a reduction in the incidence of RAAA of 49% (95% CI: 3-74%). Nine out of 11 ruptures in the invited group did not survive (mortality 82%; 95% CI: 48-98%) compared to 38 non-survivors from 51 ruptures in the control group (mortality 75%; 95% CI: 60-86%). Five years of screening resulted in an RAAA-related mortality reduction of 45% (95% CI: -15 to 74%). After 13 years of screening the incidence of RAAA was reduced by 73% (95% CI: 58-82%). Twenty-one out of 29 ruptures in the invited group did not survive (mortality 72%; 95% CI: 53-87%) compared to 64 non-survivors from 82 ruptures in the control group (mortality 78%; 95% CI: 68-86%). Thirteen years screening resulted in a reduction of mortality from RAAA of 75% (95% CI: 58-84%). The number needed to screen to prevent one death reduced from 1380 after 5 years to 505 after 13 years. The number of elective AAA operations needed to prevent one death reduced from 6 after 5 years to 4 after 13 years. CONCLUSION: AAA screening becomes increasingly beneficial as screening continues over the longer term. Benefits continue to increase after screening has ceased.     

Implications of screening for abdominal aortic aneurysms on surgical workload

BACKGROUND: The Multicentre Aneurysm Screening Study (MASS) provided strong evidence for both the clinical benefit and the cost-effectiveness of a screening programme for abdominal aortic aneurysms (AAAs) in men. If a national screening programme for AAA were adopted in the UK, it would be expected to increase the elective and decrease the emergency surgical workload. METHODS: The MASS trial randomized 67,800 men aged 65-74 years to be invited to attend for ultrasonographic screening for AAA or to a control group that received no invitation. Predictions of elective and emergency surgical workload were made for a 20-year interval after the introduction of a screening programme for 65-year-old men, based on surgical rates observed in the MASS trial and national mortality statistics. RESULTS: For a district general hospital serving a population of 400,000, there was an estimated reduction from nine emergency operations per year before introduction of the screening programme to three emergency operations annually in men aged 65 years and over by the end of the 20-year interval, and an increase from 24 to 43 AAA operations overall. The corresponding estimated annual costs for all AAA surgery increased by 47 per cent, from pound 209,000 to pound 308,000. These results were not affected by changes in the underlying assumptions. CONCLUSION: The results support the expectation of very few emergency operations, and principally elective operations, being performed following the introduction of a screening programme. For a typical district general hospital, a screening programme would be expected to lead to two additional elective AAA operations per month, and to save 11 AAA-related deaths per year.     

A population based screening of abdominal aortic aneurysms (AAA)

The prevalence of abdominal aortic aneurysm (AAA) in a defined population of elderly men and its correlation to some risk factors were studied in the population cohort "men born in 1914 from Malm?". A total of 499 were invited to attend and 375 (75%) did so. The aorta could be visualised with ultrasound in 364 patients, 39 (10.7%) of whom had aneurysmal changes. The presence of an AAA was related to the findings at a general health examination undertaken 5 years previously. Tobacco and alcohol consumption, impaired lung function and a history of angina pectoris were related to the presence of an AAA. No relationship was found between an AAA and hypertension, hyperlipidaemia or hyperglycaemia. A decreased tissue elasticity as a common denominator for the lung function impairment and development of AAA is discussed.     

Epidemiology of abdominal aortic aneurysms in the Asian community

BACKGROUND: Studies relating to the ethnic origin of patients with an abdominal aortic aneurysm (AAA) are few and are mainly concerned with the differences between black and white Americans. The purpose of this study was to determine whether the incidence of AAA among the Asian population of Bradford is different from that in the Caucasian population. METHODS: A retrospective study of patients with an AAA was carried out between 1990 and 1997 using data collected by the Patient Administrative Service, personal databases of the vascular consultants and theatre records. Information about the ethnic composition of the population of Bradford was obtained from the 1991 national census. Demographic data, including ethnic origin and clinical details, were obtained from patient notes. RESULTS: Two hundred and thirty-three patients with an AAA were identified during the study interval. The Asian population comprised 14.0 per cent of the total population of Bradford. Twenty-eight AAAs would be expected per year. All of the aneurysms identified occurred in the Caucasian population and none in the Asian community. CONCLUSION: These early results suggest that AAA is rare among the Asian population.     

Psychological consequences of screening for abdominal aortic aneurysm and conservative treatment of small abdominal aortic aneurysms.

OBJECTIVE: To describe the potential psychological consequences of screening for abdominal aortic aneurysms (AAAs). METHODS: The participants were prospectively and randomly sampled from a randomised screening trial for AAA and asked to complete a validated generic and global anonymous quality of life (QL) questionnaire by self-assessment (ScreenQL). Material case-control study: ScreenQL was completed once by 168 (48%) of 350 non-responders to screening, 271 (81%) of 335 attenders before screening, 286 (85%) of 335 attenders after screening, 127 (85%) of 149 with a small AAA diagnosed at screening, and 231 (66%) of 350 who were randomised not to be offered screening for AAA (controls). Prospective study (paired data): 127 men having a small AAA diagnosed. Twenty-nine (81%) of 36 men operated after initial conservative treatment. RESULTS: Initially, the QL score was 5% lower among men with a small AAA compared to the controls (p<0.05), mainly because of poorer health perception. The QL score declined significantly further to 7% below control values during the period of conservative treatment. This impairment was mainly due to a 21% and 15% reduction in scores relating to health perception and psychosomatic distress, respectively. However, all scores improved to control levels in patients operated on. The QL of attending men for screening was significantly lower than that of the controls and the attenders after the screening. No differences were noticed concerning the non-attenders. CONCLUSION: The offer of screening causes transient psychological stress in subjects found not to have AAA. However, diagnosis of an AAA seems to impair QL permanently and progressively in conservatively treated cases. This impairment seems reversible by operation. Nevertheless, the impairment seems considerable, and must be considered in the management of AAA and in the final evaluation of screening for AAA.     

The management of ruptured abdominal aortic aneurysms: screening for abdominal aortic aneurysm and incidence of rupture

Twenty-five years have passed since the first randomised controlled trial began its recruitment for screening for abdominal aortic aneurysm (AAA) in men aged 65 and above. Since this and other randomised trials, all launched in the late 80s and 90s of the last century, the epidemiologic profile of abdominal aortic aneurysm may have changed. The trials reported an AAA prevalence in the range of 4-7% for men aged 65 years or more. AAA-related mortality was significantly improved by screening, and after 13 years, the largest trial showed a benefit for all-cause mortality. Screening also was shown to be cost-effective. Today, there are studies showing a substantial decrease of AAA prevalence to sometimes less than 2% in men aged ≥ 65 years and there is evidence that the incidence of ruptured aneurysm and mortality from AAA is also declining. This decline preceded the implementation of screening programmes but may be due to a change in risk factor management. The prevalence of smoking has decreased and there has been improvement in the control of hypertension and a rising use of statins for cardiovascular risk prevention. Additionally, there is a shift of the burden to the older age group of ≥ 75 years. Such radical changes may influence screening policy and it is worth reflecting on the optimum age of screening - it might be better to screen at ages >65 years - or rescreening 5 to 10 years after the first screen.     

Endovascular repair for abdominal aortic aneurysms: initial experience of an endograft programme

OBJECTIVE: To evaluate early clinical results of elective endovascular repair of abdominal aortic aneurysms during the initial phase of an aortic endograft programme and to compare them with conventional open surgery. METHODS: Between July 1999 and September 2001, all patients with infrarenal abdominal aortic aneurysms undergoing elective repair were studied. The results of endovascular repair were compared with those of conventional repair. RESULTS: Twenty-seven endovascular repairs (24 men and three women; mean age, 74 yr) and 25 conventional repairs (19 men and six women; mean age, 73 yr) for infrarenal abdominal aortic aneurysms were evaluated. The aneurysm diameters in the two groups were similar (mean, 6.1 cm in the endovascular repair group and 6.6 cm in the conventional repair group). The comorbidities of the two groups were also comparable. The duration of operation was longer in the endograft group (249 +/- 86 min vs. 206 +/- 56 min), while the blood loss was significantly less (600 +/- 486 mL vs. 1074 +/- 1220 mL). The length of stay in the Intensive Care Unit (ICU) and the overall duration of hospitalization was also significantly less in the endograft group (1 +/- 1 d vs. 3 +/- 2 d in ICU; 9 +/- 5 d vs. 13 +/- 6 d of hospitalization). There was one hospital death in each group (4%), and the complications were similar between the two groups. During a mean follow-up period of 11.6 +/- 7.5 months, there was no rupture or open conversion in the endograft group. CONCLUSIONS: In the initial phase of the aortic endograft programme, the mortality and morbidity were acceptable and comparable to that of open surgery.     

General practice-based population screening for abdominal aortic aneurysms: a pilot study

All 1195 male patients aged between 65 and 74 years on the Family Practitioner Committee register for the four group practices in Stroud, UK were invited for a health screening check. The examinations included abdominal ultrasonography to measure maximum aortic diameter, measurement of blood pressure and recording of smoking habits. An attendance rate of 76 per cent was achieved (906 patients). Seventy-one patients (7.8 per cent) were found to have aortic diameters greater than 2.5 cm and 14 (1.5 per cent) had aortic diameters greater than 4.0 cm. Aneurysms were more common in smokers and in hypertensive patients. However, restriction of screening to patients with these risk factors would have led to a number of aneurysms remaining undiscovered. We recommend therefore that ultrasound screening for abdominal aortic aneurysms should be offered to all men between the ages of 65 and 74 years.     

Optimal interval screening and surveillance of abdominal aortic aneurysms.

OBJECTIVES: to determine safe and optimal intervals of rescreening and surveillance for AAA. METHODS: hospital-based mass screening of 6339 65-73-year-old men from 1994-98. 76.4% attended. One hundred and ninety-one (4%) had AAA53 cm. Twenty-four (0.5%) were initially >5 cm and referred for surgery, while the rest were offered annual control scans to check for expansion. Later, all 348 (7.5%) men who 3 to 5 years ago had an ectatic aorta (infrarenal aortic diameter of 25-29 mm or distal/renal aortic diameter ratio >1.2) were offered rescreening. Of these, 62 (18%) died before rescanning, while 248 of the survivors attended rescreening (87%). Furthermore, a random sample of 380 of those with non-ectatic aortas were offered rescreening. Of these, 49 (13%) died before rescreening (p=0.06), while 275 (83%) of the survivors attended re-screening. RESULTS: none of the controls had developed AAA. Of those who initially had an 25-29 mm aorta, 29% had developed AAA (size range 30-48 mm) with expansion rates varying from 1.0 to 4.7 mm/year. Only 3.5% with a ratio >1.2 developed AAA (size range: 30-34 mm) with expansion rates from 1.3 to 2.4 mm/year. During the fourth year of surveillance some AAA initially sized below 3.5 cm expanded to above 5 cm, while some sized 3.5-3.9 cm did so during the second year, >4 cm did so during the first year of surveillance. CONCLUSION: rescreening for AAA can be restricted to initially ectatic aortas sized 25-29 mm at 5-year intervals. Surveillance of small AAA can be restricted to 1-4 year intervals.