What is the evidence that screening is effective?
In 1988, researchers in Chichester, England, randomized > 6000 men ages 65 to 80 years to either a control group or a group that was offered a one-time US screen for AAA. After 15 years of follow-up, no significant difference in AAA mortality was seen between the groups, although 26% of those invited for screening declined to participate and accounted for more than half of the AAA-related deaths in the group receiving an invitation for screening.8
The MASS Trial,9 another British study, began in 1997 and screened men ages 65 to 74. More than 67,000 men were randomized, with 1 group invited for AAA screening and the other serving as a control. The final report on this trial was published in 2012. After 13 years of follow-up, there was a 42% reduction in AAA-related deaths in the group invited for screening, a small reduction in all-cause mortality, and a significant reduction in risk of AAA rupture (hazard ratio = 0.57). The researchers noted that 216 patients would have to be invited for screening to prevent 1 death over 13 years. They also reported that 21% of the invited patients that had an AAA-related death had an initial scan that was negative for AAA (aortic diameter < 3 cm). However, despite this finding, screening still appeared to be beneficial.
Lindholdt et al10 randomized > 12,000 Danish men ages 64 to 73 to serve as controls or to be invited for US screening for AAA. After 13 years of follow-up, those invited for screening had a 66% relative risk reduction in AAA-related mortality, with screening considered cost effective. There were no differences between the groups in all-cause mortality. Conversely, the Western Australia Trial studied an older group of men, ages 64 to 83, but was unable to show a benefit of screening in lowering AAA-related mortality.11
Tikagi et al6 performed a meta-analysis on the data from the 4 trials above and reported up to 15 years of follow-up. Patients who attended screening sessions had a reduction in all-cause mortality with an odds ratio (OR) of 0.6, and a marked reduction in AAA-related mortality with an OR of 0.4. The favorable data on screening have prompted the United Kingdom and Sweden to offer screening to all men ≥ 65 years, based on the current estimate of a 1% prevalence of AAA, although screening is felt to remain cost effective down to a prevalence of 0.35%.12
Massachusetts General Hospital also reported13 that the detection rate of AAA increased, with the diagnosis made at smaller aneurysm dimensions, following publication of the US Preventive Services Task Force recommendations (reviewed below).
Continue to: When to screen