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Dr Matthew Mell (Madison, Wis). Could you speculate on the influence of smoking in your patient cohort and whether it may have acted as a confounding variable if a family smoking history was more prevalent?

Dr Hultgren. Well, that's impossible to say, since it's a register-based study. Looking at the comorbid conditions, you get a hint that probably smoking prevalence is much higher in the case group than in the control group. It's well known that smoking habits as well as dietary habits is inherited too through a social pattern. So probably it is much more prevalent in the case group.

Dr Louis Nguyen (Boston, Mass). I have a question regarding aneurysm screening in Sweden, because I am concerned that the likelihood for detection of AAA is different in your case group versus control group. A patient with a known aneurysm will more likely be told to have his relatives checked for an aneurysm as well. This scenario would then produce a higher incidence of relatives with AAA. For patients with no known AAA, their relatives would not have any reason to be screened unless there was a broad program in place. Can you tell us if AAA screening is routine and widespread in Sweden? Also, could you comment on whether or not the likelihood for detection of aneurysms in the relatives of your two groups was equivalent?

Dr Hultgren. Yes, I think that's an important point, and we've discussed that quite a lot. But we think at least by adjusting for the comorbid conditions you get rid of some of the problem with over-diagnosing comorbid patients. Maybe it isn't that bad that we actually do screen first-degree relatives more, because they are probably at a much higher risk, so maybe that's actually quite motivated.

Dr J. Black (Baltimore, Md). Did you look at the age of presentation of the index cases with aneurysms and the number of affected relatives? The implication being that younger patients with more affected relatives might have a genetic syndrome and would prompt referral. Do you have that data available within the set?

Dr Hultgren. In the analysis of subgroups, we did get a higher odds ratio (OR) for younger patients having a higher risk for the first-degree relative, it didn't become significant compared to the OR of 1.8 in the older age groups. In the analysis of the thoracic patients, younger age was a higher risk to develop disease than in the AAA group.

Dr K.W. Johnston (Toronto, Ontario, Canada). What genetic testing do you consider doing in a patient with a positive family history of aneurysm to try and determine if they do indeed have an increased risk?

Dr Hultgren. Well, there have been some studies internationally looking at genes and genetic pathways, and nobody has really succeeded in finding one or two especially important genes. We will start a national screening program in a couple of years, and we are going to do a genetic screening based on that, let me come back in 3 years and I'll tell you more about it.