AAA screening in older males: Should we?

Last week, a Danish group made headlines with their Lancet study showing that “Triple-screening” older men for abdominal aortic aneurysm (AAA), peripheral arterial disease (PAD), and hypertension reduced 5-year mortality by 7%.

This was seen as validating the current Canadian guidelines that call for all males 65-75 years old to undergo a one-time ultrasound to rule out a AAA, in addition to women with risk factors (smoking history, family history of AAA, or cerebrovascular disease).

So, is it time to move forward with a formal population-based screening program? Let me provide some food for thought using some of my own practice data.

In the Danish study, 21% of the subjects were active smokers at baseline. In my practice 10 of 154 (6.5%) men 65-75yo are smokers (3 of the 10 smokers smoke only cigars or pipes infrequently, and 3 men in the cohort have no smoking data available). We know that smoking is the strongest risk factor for development of AAA, as current smokers are 7.6 times more likely to have an AAA than nonsmokers, and even ex-smokers are 3.0 times more likely to have an AAA than nonsmokers. Screening a population where smoking is less prevalent will provide far less of a mortality benefit than was seen in the Danish population, with a larger number needed to screen.

In response to the Canadian guidelines, I have made an effort in my practice to increase AAA screening rates over the past few years, with 113 of 157 (72.0%) men 65-75yo completing an ultrasound screen. Of the 113, only 2 have a AAA, which is significantly lower than the 3.3% AAA rate seen in the Danish study. Lower smoking rates overall likely translating to the lower rate of AAA.

Looking at all age groups, 14 of my patients have a current or past AAA (7 men, 7 women). 10 of the 14 are former smokers, and none are current smokers. 12 of the 14 are over the age of 75.

The number needed to screen for men >65yo to prevent one AAA related mortality is 769, but this includes both smokers and non-smokers which are likely inflating the numbers. If we are going to implement a program, let’s start with the high-yield groups of smokers/ex-smokers first where we know we will see a see the biggest benefit.

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