Abdominal aortic aneurysm screening: recommendations and controversies

Prevalence of abdominal aortic aneurysms in patients with lung cancer

OBJECTIVE

Concomitance of abdominal aortic aneurysm (AAA) and primary lung cancer (LC) is not uncommon due to several shared risk factors. To evaluate the incidence of this association, analysis of the National Inpatient Sample database was utilized.

METHODS

A retrospective analysis of the National Inpatient Sample database between 2014 and 2018 for all patients diagnosed with primary LC was performed. The differences in the reported findings between the LC and control groups were assessed using the Pearson χ², Fisher exact, Student t, and/or Mann-Whitney U tests where appropriate. Multivariable logistic regression analysis was conducted to determine independent predictors of the presence of documented AAA.

RESULTS

A total of 158,904 patients were identified. Of these, 2430 patients (1.53%) were diagnosed with AAA and 156,474 (98.47%) without AAA. In the multivariable model, LC patients had higher odds of AAA compared with the general population (odds ratio, 1.43; 95% confidence interval, 1.35-1.51). In all age groups, female smokers had a higher rate of AAA compared with female nonsmokers (age <60 years, 0.13% vs 0.04%; 60-69 years, 0.77% vs 0.34%; 70-79 years, 1.65% vs 0.69%; and >80 years, 2.63% vs 1.31%; all P < .001).

CONCLUSIONS

LC and AAA share similar risk factors, which may explain the higher AAA prevalence among patients with LC. Given the higher prevalence of AAA in smokers compared with nonsmokers across all age groups in both male and female patients with LC, further sex-based studies investigating the overall mortality and morbidity benefits of AAA screening among patients with LC are highly warranted. This consideration would potentially address the sex disparity in outcomes for AAA management.

Biomechanical Investigation of Disturbed Hemodynamics-Induced Tissue Degeneration in Abdominal Aortic Aneurysms Using Computational and Experimental Techniques

Abdominal aortic aneurysm (AAA) is the dilatation of the aorta beyond 50% of the normal vessel diameter. It is reported that 4-8% of men and 0.5-1% of women above 50 years of age bear an AAA and it accounts for ~15,000 deaths per year in the United States alone. If left untreated, AAA might gradually expand until rupture; the most catastrophic complication of the aneurysmal disease that is accompanied by a striking overall mortality of 80%. The precise mechanisms leading to AAA rupture remains unclear. Therefore, characterization of disturbed hemodynamics within AAAs will help to understand the mechanobiological development of the condition which will contribute to novel therapies for the condition. Due to geometrical complexities, it is challenging to directly quantify disturbed flows for AAAs clinically. Two other approaches for this investigation are computational modeling and experimental flow measurement. In computational modeling, the problem is first defined mathematically, and the solution is approximated with numerical techniques to get characteristics of flow. In experimental flow measurement, once the setup providing physiological flow pattern in a phantom geometry is constructed, velocity measurement system such as particle image velocimetry (PIV) enables characterization of the flow. We witness increasing number of applications of these complimentary approaches for AAA investigations in recent years. In this paper, we outline the details of computational modeling procedures and experimental settings and summarize important findings from recent studies, which will help researchers for AAA investigations and rupture mechanics.

Screening for abdominal aortic aneurysms

Ruptured AAA ranks as the 15th leading cause of death overall in the United States, and the 10th leading cause of death in men older than 55 years. Early identification of AAA can save livesand diminish cost. Screening programs havebeen implemented and studied in other countries and have shown a measurable and significant reduction in overall rate of aneurysm-related death. Currently, one-time screening of a small number of ever-smoking men when they turn 65 screening is not widely used in the United States and Medicare, at best, provides one-time screening of a small number of ever-smoking men when they turn 65 years old. Because more than 30,000 individuals in the United States die each year of ruptured AAA, a great deal of progress must be made to eradicate rupture from aneurysmal disease. A more comprehensive system of screening is required and this should be uniformly applied to the U.S. population. It is hoped that scoring systems such as the one outlined in this article, if widely adopted, can greatly enhance screening for aneurysmal disease and prevent the high mortality that stems from this serious vascular disease.

First-year results of a national abdominal aortic aneurysm screening programme in a single centre

Background

The UK Multicentre Aneurysm Screening Study (MASS) demonstrated reduced mortality from screening for abdominal aortic aneurysm (AAA). As a result, the National Health Service AAA Screening Programme was introduced in England. This study reports the results from an early-implementation screening centre.

Methods

Men aged 65 years were invited to attend an ultrasound assessment. Data were analysed for 15 months from the onset of the screening programme.

Results

A total of 6091 men aged 65 years were invited between April 2009 and June 2010, of whom 2037 (33·4 per cent) failed to attend. There were 162 self-referrals (median age 71·3 years) so that 4216 men were screened. Of those scanned, 4146 (98·3 per cent) had an aortic diameter of less than 3·0 cm, 65 (1·5 per cent) had an aneurysm measuring 3·0–5·4 cm, and five (0·1 per cent) had an aneurysm with a diameter of 5·5 cm and above. The presence of an aneurysm was more common in those who self-referred than in the invited group (P &lt; 0·001). All 70 screen-detected aneurysms were found in white men.

Conclusion

The prevalence of AAA was lower than expected. This reflects the younger age of this cohort compared with those in published large multicentre studies and the diverse ethnic background of the local population. Copyright © 2011 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd.

Analysis of risk factors for abdominal aortic aneurysm in a cohort of more than 3 million individuals

BACKGROUND

Abdominal aortic aneurysm (AAA) disease is an insidious condition with an 85% chance of death after rupture. Ultrasound screening can reduce mortality, but its use is advocated only for a limited subset of the population at risk.

METHODS

We used data from a retrospective cohort of 3.1 million patients who completed a medical and lifestyle questionnaire and were evaluated by ultrasound imaging for the presence of AAA by Life Line Screening in 2003 to 2008. Risk factors associated with AAA were identified using multivariable logistic regression analysis.

RESULTS

We observed a positive association with increasing years of smoking and cigarettes smoked and a negative association with smoking cessation. Excess weight was associated with increased risk, whereas exercise and consumption of nuts, vegetables, and fruits were associated with reduced risk. Blacks, Hispanics, and Asians had lower risk of AAA than whites and Native Americans. Well-known risk factors were reaffirmed, including male gender, age, family history, and cardiovascular disease. A predictive scoring system was created that identifies aneurysms more efficiently than current criteria and includes women, nonsmokers, and individuals aged <65 years. Using this model on national statistics of risk factors prevalence, we estimated 1.1 million AAAs in the United States, of which 569,000 are among women, nonsmokers, and individuals aged <65 years.

CONCLUSIONS

Smoking cessation and a healthy lifestyle are associated with lower risk of AAA. We estimated that about half of the patients with AAA disease are not eligible for screening under current guidelines. We have created a high-yield screening algorithm that expands the target population for screening by including at-risk individuals not identified with existing screening criteria.

Rapid assessment of abdominal aortic aneurysms by 3-dimensional ultrasonography

OBJECTIVE

The purpose of this study was to assess the application and accuracy of 3-dimensional (3D) volume acquisition ultrasonography in the measurement of abdominal aortic aneurysms (AAAs).

METHODS

Thirty consecutive patients undergoing surveillance ultrasonographic examinations of known AAAs were scanned according to a conventional protocol, after which 3D volume data sets were acquired with a commercially available mechanical transducer. Maximum aortic diameters were measured with multiplanar reconstructions from the 3D volume data, and these were compared with those from the conventional technique.

RESULTS

Abdominal aortic aneurysm diameters were between 2.9 and 6.75 cm. For both anteroposterior and transverse diameters, a paired t test showed a Pearson correlation coefficient of 0.98 (significant at the P = .01 level) and a coefficient of determination of 0.96. Bland-Altman analysis showed that the mean difference between the two sets of measurements was very close to 0 (P = .05). Thus, there was no significant difference between the conventional and 3D volume measurement methods. The scan acquisition time for the 3D volume data was only 3 seconds for each set (anteroposterior and transverse).

CONCLUSIONS

Three-dimensional ultrasonography using volume acquisition offers a new opportunity to acquire fast and reliable AAA measurements. The reduced scan times can be used to allow greater patient throughput and will help cope with the increasing workload of AAA surveillance. By archiving a complete set of data, 3D ultrasonography allows subsequent analysis and comparison of measurements. This study also suggests that the technique could be used for other applications with similar efficiency gains.