Image: The risk from AAA scanning is higher than that of the aneurysm itself (Photo courtesy of Shutterstock).
A new study suggests that as abdominal aortic aneurysm (AAA) prevalence diminishes, using ultrasound scans to detect them in older men may do more harm than good.
Researchers at Sahlgrenska Academy (SA; Göteborg, Sweden), the University of Gothenburg (Sweden), the University of Copenhagen (KU; Denmark), and other institutions conducted a study involving 25,265 men aged 65 years and older who were invited to AAA screening between 2006 and 2009, and an age-matched control group of 106,087 men who had not been screened. The aim of the study was to estimate the effect of AAA screening in Sweden on disease-specific mortality, incidence, and surgery.
Individual data on the incidence of AAA, AAA mortality, and surgery for AAA were compared with data from the age-matched contemporaneous cohort of men. Adjustment for confounding factors was done by weighting the analyses with a propensity score based on cohort year, marital status, educational level, income, and whether the patient already had an AAA diagnosis at baseline. The researchers also studied incidence and mortality from AAA among all Swedish men between the ages of 40 and 99 from 1987 to 2015.
The results revealed that AAA mortality in Swedish men decreased from 36 to ten deaths per 100,000 elder men between the early 2000’s and 2015, irrespective of whether AAA screening was offered. A non-significant reduction in AAA mortality associated with screening was identified, in that just two men avoided death from AAA for every 10,000 men screened. Concomitantly, odds of AAA diagnosis and risk of elective surgery increased, so that for every 10,000 men screened, 49 were probably overdiagnosed, 19 of who also underwent avoidable surgery. The study was published on June 16, 2018, in The Lancet.
“Mortality has declined by over 70%, and this trend was seen in both screened and unscreened counties and in both screened and unscreened age groups. If the screening program had any impact at all on the decline, it was very small,” said lead author PhD student Minna Johansson, MD, of SA. “The very positive reduction in mortality was probably due to a decline in smoking. We came to the conclusion that it is doubtful that the benefits of screening outweigh the harms, and that the Swedish screening program should therefore be revisited.”
AAA is the localized dilatation of the abdominal aorta exceeding the normal diameter by more than 50%, and is the most common form of aortic aneurysm; approximately 90% occur below the kidneys. The aneurysms can extend to include one or both of the pelvic iliac arteries. The major complication of AAA is rupture, which is life-threatening, as large amounts of blood spill into the abdominal cavity, and can lead to death within minutes. Mortality of rupture repair in the hospital is 60-90%.
University of Gothenburg
University of Copenhagen