Synopsis: The USPSTF recommends one-time screening for abdominal aortic aneurysm (AAA) with ultrasonography in men ages 65 to 75 years who have ever smoked based on data from 4 RCTs from the 1980s and 1990s. Given the declining incidence of AAA in Sweden, the current utility of AAA screening and the risk of overdiagnosis/overtreatment was evaluated in this retrospective national registry-based cohort study of men aged 65 years who underwent AAA screening over a six year follow up period compared to age-matched controls. They found that despite screening, there was no difference in AAA-mortality in the screening cohort compared to controls over the follow up period (OR 0.76, 95% CI 0.38-1.52). However, the odds of having a AAA during the follow up period was significantly higher in the screening cohort (OR 1.52, 95% CI 1.16-1.99), as was the incidence of elective surgery (OR 1.59, 95% CI 1.20-2.10). Comparing their data to the largest screening trial to date, the MASS trial, they found only 7% of the benefit of screening in terms of absolute numbers (2 vs. 27 avoided deaths from AAA per 10,000 offered screening). Furthermore, they found a lower rate of over-diagnosis (49 vs 176 per 10,000 men offered screening – a 28% reduction), and a lower rate of over treatment (19 vs 37 per 10,000 men offered screening – a 51% reduction) vs. the MASS study. Since the harms of screening decreased less than the benefit, the balance between benefits and harms was deemed to be less favorable in today’s clinical setting.
There are a few limitations worth noting. The first is the somewhat short follow-up of six years after screening. A study from the Swedish Aneurysm Screening Study Group showed that at least ten years of implementation of AAA screening might be needed to show a benefit in AAA-specific mortality. Second, the concept of overtreatment and overdiagnosis is difficult to grasp in an era where strict guidelines exist for diagnosis and intervention thresholds. If physicians follow societal guidelines, treatment should not be excessive. Furthermore, there is no evidence to date in the US literature demonstrating a preponderance of aneurysm repairs that do not meet intervention criteria. Third, the article would have benefited from an analysis of the differences in mortality, as well as costs, between repair of elective and ruptured AAA (the latter of which would likely be more prominent among those not screened). Last, AAA screening has other indirect benefits, by providing practitioners the opportunity to employ preventive measures (e.g. statins, anti-platelet therapy, and hypertension management) to reduce the risk of all-cause mortality in this population with increased burden of cardiovascsular disease.