Feature: Expanded AAA screening algorithm targets 'missed' populations
“This study dealt with a major public health issue [AAA], which results in an estimated 15,000 U.S. deaths per year,” said Greco. “There is a problem with the current screening approach, which is mainly the exclusion of groups, particularly women, who suffer a high number of AAA ruptures and deaths.”
In-hospital survival rates for treating a ruptured AAA is reported to be just more than 50 percent and researchers estimated that 5 percent of the 200,000 cases of sudden deaths that occur each year may be directly linked to AAA.
Greco and his colleagues from the Mount Sinai School of Medicine in New York City and from the Vascular Surgery Screening Task Force of the Society for Vascular Surgery utilized the Life Line Screening database—a cohort of 3.1 million individuals who received, between 2003 and 2008, a lifestyle and medical questionnaire in addition to ultrasound imaging to detect the presence of AAA—to analyze risk factors for the disease.
Currently, guidelines put forth by the U.S. Preventive Services Task Force (USPSTF) recommend AAA screening only in men aged 65 to 75 who have a history of smoking. However, Greco estimated that more than half—approximately 569,000 cases—of the existing AAA cases are among people not eligible to undergo screening, according to the USPSTF recommendations.
Therefore, Greco said, we created a scoring system where the relative impact of each risk factor is expressed by a score. “The higher the total score, the higher the AAA risk for an individual.” The scoring system allows the detection of AAA in a broader population by expanding screening to women, nonsmokers and individuals less than 65 years of age.
In the current study, Greco and colleagues compared their own risk-model scoring system to the screening process recommended by the USPSTF. Greco said that USPSTF selection criteria use smoking as a binary variable. “Either you are a smoker or you are not,” he said. Smokers are defined as those who have smoked at least 100 cigarettes in their lifetime. However, for the current study, the researchers took into account additional factors including duration of smoking, amount of cigarettes smoked and time elapsed since smoking cessation. “Smoking is a broad category. Among smokers there are individuals who are not truly at high risk,” said Greco.
In addition, the researchers found that consuming fruits, vegetables and nuts, and increasing exercise regimens decreased a patient's risk for AAA. But, a body mass index greater than 25 kg/m2 can boost a patient’s risk of AAA. “It remains possible that diet and exercise are surrogates for other important and unmeasured factors that contribute to a healthy lifestyle,” the authors wrote.
“Our scoring system could have a tremendous impact on the effectiveness and the cost of our screening program. As compared to the status quo, we can pick up a greater number of AAAs, using the same number of screenings or less,” said Greco. “Also we can detect AAAs in populations at risk that have been neglected by the current screening policy.”
However, Greco said that while the scoring system used in the study showed promising results, the screening process will need to be validated using a different cohort.
Additionally, Greco said the cost effectiveness of the screening process must be assessed. While the screening process may better to detect AAAs, the induced costs associated with the monitoring and the elective treatment of the additional AAAs that would be discovered in different patient groups has not been examined.
“A scoring system that gives you the ability to pick up a greater number of patients with less screening or same number and to detect AAAs among a broader population argues for fundamental changes in current screening policy,” concluded Greco.
The study was funded by a grant to the Society for Vascular Surgery from Lifeline Screening.