Screening programmes for abdominal aortic aneurysm (AAA) have been introduced in the UK and Sweden on the basis of clinical trials showing the beneficial effect of this approach in reducing mortality from AAA. A study now calls these programmes into question by revealing that screening did not contribute to the reduction of AAA mortality in Sweden since the programme implementation, and could even be harmful.

Credit: V. Summersby/Macmillan Publishers Limited

AAA incidence has dramatically decreased in the UK and Sweden in the past 30 years. “Because of the rapidly changing epidemiology of AAA, the clinical trials on AAA screening are outdated and the effects of screening in contemporary populations are unknown,” explains study investigator Minna Johansson. In this retrospective, registry-based, cohort study, the investigators assessed the incidence of AAA and of disease-specific mortality and surgery in men aged 65 years who were screened for the disease between 2006 and 2009, compared with non-screened, age-matched men. “In Sweden, the screening programme was introduced stepwise, county by county; this offered a unique possibility to compare contemporary screened and non-screened men of the same age,” says Johansson.

Mortality from AAA decreased >70% between the early 2000s and 2015 in men aged 65–74 years, in both screening and control cohorts, and the study only reported an additional, non-significant reduction of 24% with screening. Other factors, notably the reduction in the prevalence of smoking, might therefore explain the reduction in AAA mortality. In addition, the odds of being diagnosed with AAA and of having surgery were higher in the screening cohort than in the control group. Altogether, the results indicated that for every 10,000 men screened, 2 men avoided death from AAA but 49 men were overdiagnosed and 19 underwent avoidable surgery.

Given the substantially less favourable benefit-to-harm balance found in this study, the AAA screening programme should be revaluated.

Given the substantially less favourable benefit-to-harm balance found in this study, the AAA screening programme should be revaluated.

“When we invite asymptomatic citizens to an intervention, we must be reasonably certain that this intervention causes more good than harm. It is doubtful whether this is the case for AAA screening,” concludes Johansson.