Influence of diagnostic criteria on the prevalence of abdominal aortic aneurysm

Cost-effectiveness of different screening strategies for abdominal aortic aneurysm

OBJECTIVE

The primary objective of this study was to develop a simulation model to assess the cost-effectiveness of different screening strategies for abdominal aortic aneurysms (AAAs) in men.

METHODS

A systematic review of the literature was conducted for different screening strategies in terms of age (60, 65, or 70 years) and risk profiles (all men or specific high-risk groups) of the screened population, and rescreening after 5 or 10 years. These data were analyzed in a Markov simulation cohort model.

RESULTS

The cost per life year gained for different screening strategies ranged from US 8,309 dollars to US 14,084 dollars and was estimated at US 10,474 dollars when 65-year-old men were screened once. Screening 60-year-old men was equally cost-effective, with the advantage of more life years gained. We demonstrated a trade-off between high prevalence of AAA and lower life expectancy, eliminating the expected benefits of screening high-risk groups such as smokers (US 10,695 dollars) or cardiovascular patients (US 10,392 dollars). Assuming general population utility resulted in a cost per quality-adjusted life year (QALY) gained of US 13,900 dollars, whereas a hypothetical 5% reduction in utility among men with a screening-detected AAA raised the cost per QALY gained to US 75,100 dollars.

CONCLUSION

This Markov model, which was based on a systematic review of the literature, supplied information on the estimated cost-effectiveness of different screening strategies. Screening men for AAA may be cost-effective in the long-term. Different screening strategies and quality-of-life effects related to screening for AAA need to be evaluated in future clinical studies.

Risk factors associated with abdominal aortic aneurysm: a population-based study with historical and current data

OBJECTIVES

To define risk factors associated with the development of abdominal aortic aneurysm (AAA) in a population-based case-control study.

MATERIAL AND METHODS

Thirty-five patients found to have AAA at screening were compared with 140 age- and sex-matched controls. Three distinct comparisons were made. Current risk factors in both cohorts were compared. Because data were also available for both cohorts from a study conducted 12 years previously, a historical comparison was made between risk factors identified at the time of this initial evaluation. A longitudinal comparison was made between historical and current risk factors.

RESULTS

Elevated low-density-lipoprotein cholesterol, total cholesterol, and triglyceride levels 12 years before AAA screening were associated with current AAA with an odds ratio (OR) of 2.3 (95% confidence interval [CI], 1.2 to 4.4); OR, 1.9 (95% CI, 1.3 to 2.8); and OR, 1.9 (95% CI,1.2 to 3.1)/mmol/L, respectively. Current variables assessed at AAA screening that were associated with AAA were: A history of atherosclerotic disease, OR, 3.8 (95% CI, 1.7 to 8.5); having a first-degree relative with AAA, OR, 4.4 (95% CI, 1.5 to 13.0); current smoking, OR, 5.2 (95% CI, 1.6 to 16.8); high-density-lipoprotein cholesterol level, OR, 0.1 (95% CI, 0.02 to 0.7)/mmol/L; and high-sensitivity C-reactive protein (hsCRP) level, OR, 1.1 (95% CI, 1.01 to 1.2)/mg/L. Hypertension and diabetes were not associated with AAA. A significant increase of hsCRP over time (12 years) was observed in AAA patients ( P = .039) but not among controls. The variables of a history of atherosclerosis, smoking, and family history of AAA appear to interact synergistically to increase the prevalence of AAA ( P < .001).

CONCLUSION

Among traditional risk factors for atherosclerosis, some were associated with AAA and others were not, indicating complex and partly different causes. Inflammation and heredity appear to be important factors in the development of AAA.

Low Quality of Life Prior to Screening for Abdominal Aortic Aneurysm: A Possible Risk Factor for Negative Mental Effects

The objective of this study was to evaluate the effect on quality of life (QOL) of screening for abdominal aortic aneurysm (AAA) in a population-based AAA screening program. Twenty-four patients with screening-detected AAA and 45 controls with normal aortic diameter were studied in a prospective, controlled, population-based study. Prior to and 12 months after the ultrasonography examination, all participants completed Short-Form 36 and at 12 months, 10 AAA-specific questions were added. Comparisons were made between the two groups (AAA patients and controls), within each group, and between the groups and norms for the general Swedish population in the same age interval. Our results showed that screening for AAA results in impairment of QOL among those who have the disease and who suffered a low QOL prior to screening. Among those who had an age-adjusted normal QOL prior to screening and who were found to have the disease, and among those who were found to have normal aortas, no negative effect on QOL was observed. Thus, low QOL before screening is a possible risk factor for negative mental effects of diagnosing an AAA by screening.

Aortic emergencies

Prompt recognition of actual or impending aortic emergencies is essential to the effective practice of emergency medicine. Understanding the pathophysiologic principles and awareness of the potential subtleties in the clinical presentations of aortic dissection, aneurysm, and occlusive disease are prerequisites to this task. Knowledge of current diagnostic modalities is also important if these entities are to be identified rapidly and managed efficiently to maximize the potential for a good patient outcome. Awareness of the potential complications of these conditions and the necessary interventional and resuscitative measures that might be called for in the appropriate clinical setting are likewise essential requirements for the EP. Appropriate surgical consultation and mobilization of operative resources form the backbone of appropriate management in the patient who has an aortic emergency.

Mass screening on abdominal aortic aneurysm in men aged 60 to 65 years in The Netherlands. Impact on life expectancy and cost-effectiveness using a Markov model

OBJECTIVES

To predict the costs and effects on life expectancy of an AAA screening programme.

METHODS

A Markov model was designed to compare the effects of a single screening for a cohort of men 60-65 years with the current no screening strategy. The following health states were distinguished: no AAA, unknown small AAA, follow-up small AAA, unknown large AAA, repaired AAA, rejected large AAA and death. Transition rates between the health states were simulated using cycle times of one year. Transition probabilities were derived from literature and a previous feasibility study. Incremental costs per life year saved were calculated. Sensitivity analyses and discounting for future effects were performed.

RESULTS

The expected individual AAA costs for non-screening and AAA screening were euro; 196 and euro; 530 respectively. A difference of 3.5 months life expectancy was found in favour of screening leading to euro; 1176/life-year gained. Costs increased as compliance fell. With a discount rate of 4% the costs are euro; 2021/life-year gained.

CONCLUSIONS

One-time ultrasonographic screening for AAA in men aged 60-65 years appears to be cost-effective.

Screening for asymptomatic internal carotid artery stenosis and aneurysm of the abdominal aorta: comparing the yield between patients with manifest atherosclerosis and patients with risk factors for atherosclerosis only

OBJECTIVE

The purpose of this study was to investigate whether screening for internal carotid artery stenosis (ICAS) and aneurysm of the abdominal aorta (AAA) is indicated in patients with either manifest atherosclerotic disease or with only risk factors for atherosclerosis.

STUDY DESIGN

Data were obtained for 2274 patients enrolled in the SMART study, an ongoing single-center, prospective cohort study of patients referred to our vascular center with manifest atherosclerotic disease (peripheral atherosclerotic disease [PAD]; transient ischemic attack [TIA], stroke, or ICAS; AAA; angina pectoris; or myocardial infarction [MI]) or with only risk factors for atherosclerosis (diabetes mellitus, hypertension, hyperlipidemia). The presence of ICAS or AAA was determined with duplex scanning and ultrasonography.

RESULTS

The prevalence of ICAS 70% or greater is low in patients with risk factors for atherosclerosis only (1.8%-2.3%), intermediate in patients with angina pectoris or MI (3.1%), and highest in patients with PAD (12.5%) or AAA (8.8%). The prevalence of AAA 3 cm or larger is low in patients with risk factors for atherosclerosis only (0.4-1.6%), intermediate in patients with angina pectoris or MI (2.6%), and highest in patients with PAD (6.5%) or TIA, stroke, or ICAS (6.5%). The prevalence of AAA larger than 5 cm is low in all of the considered patient groups. The yield of screening can be optimized through selection on the basis of simple patient characteristics. In patients with PAD, selecting those with advanced age (>54 years) increased the prevalence of ICAS to 21.8%. Selecting patients with lower diastolic blood pressure (<83 mm Hg) increased the prevalence of ICAS to 17.9%. In patients with both advanced age and lower diastolic blood pressure, the prevalence of ICAS increased to 34.7%. Selecting patients with advanced age increased the prevalence of AAA 3 cm or larger to 9.6%. In patients with TIA, stroke, or ICAS, selecting those with advanced age increased the prevalence of AAA 3 cm or larger to 8.2%. Selecting patients with taller stature (>169 cm) increased the prevalence of AAA 3 cm or larger to 9.3%. In patients with advanced age and taller stature, the prevalence of AAA 3 cm or larger increased to 13.1%.

CONCLUSIONS

Screening for ICAS should be limited to patients referred with PAD or AAA, especially those with advanced age or with low diastolic blood pressure. Screening for AAA should be limited to patients referred with PAD or with TIA, stroke, or ICAS, particularly those with advanced age or tall stature. In patients referred with angina pectoris or MI and those referred with only risk factors for atherosclerosis, screening cannot be endorsed.

[Screening of the abdominal aortic aneurysms during an echocardiography]

We examined the abdominal aorta by ultrasound in 1106 patients during transthoracic echocardiography, whatever the reason of the echocardiography, to track abdominal aortic aneurysms. The study group comprised 822 men and 284 women. We found 88 patients having an abdominal aorta with a diameter of more than 23 mm and 11 patients with a diameter of more than 35 mm. Ninety sixteen per cent of the patients having an aortic ecstasy are more than fifty years old. Ther are more smokers among the patients having an aortic ecstasy. In conclusion, the track of the ecstasies and the abdominal aortic aneurysms is easily realizable during an echocardiography and presents a good rentability.

Measuring the abdominal aorta with ultrasonography and computed tomography - difference and variability

OBJECTIVES

The aim of this study was to estimate the agreement between ultrasonography (US) and computed tomography (CT) in the measurement of aortic diameter in subjects with and without abdominal aortic aneurysms (AAA).

MATERIAL AND METHODS

Sixty-one subjects were investigated, 33 with a diameter >30mm and 28 with a diameter <30mm. Difference and variabily anteroposterior (AP) and transverse (TR) diameters were analysed.

RESULTS

In non-aneurysmal aortas US gave larger AP: 2.8mm (95% CI 1.7-4.0) and TR: 3.8mm (2.3-5.3) diameter. In AAAs the mean diameter did not differ significantly. In non-aneurysmal aortas we expect 95% of differences to be <5.7mm in AP and <7.6mm in TR measurements. In aneurysmal aortas we expect 95% of differences to be <8.0mm in AP and <10.6mm in TR measurements.

CONCLUSION

The difference and variability between US and CT varies depends on the diameter of the aorta and how it is measured. These differences have importance for clinical practice and for research.