Blue light special: AAA screening at Kmart in the disease-mongering aisle 8

Now, in addition to all the other stuff  there, you can go to Kmart and get screened for abdominal aortic aneurysm (AAA). Some people will even receive free ultrasound tests. The new program, from the Find the AAAnswers Coalition, was announced on Friday. It’s a perfect example of disease mongering, the selling of a sickness to increase sales of a drug or device.

In this case, the expenses of the program and the coalition are entirely underwritten by Medtronic, which sells abdominal stent grafts used to repair AAAs, and the members of the coalition include organizations like the Peripheral Vascular Surgical Society, the Society for Vascular Surgery, and the Society for Vascular Ultrasound, whose members may derive a significant portion of their income from performing AAA repairs and screening.

No one is disputing that AAA is a bad thing, or that, when appropriate, AAA repair is a life-saving procedure. As noted correctly on the Find the AAAnswers Coalition website, a ruptured AAA is a catastrophic event. Most people with a ruptured AAA outside the hospital don’t survive, making AAA the third leading cause of sudden death in men over 60.

But that doesn’t mean that more widespread screening is in the best interest of the public. Here’s the problem: the US Preventive Services Task Force (USPSTF) guidelines for AAA screening are the best current source for information about who is eligible for AAA screening. The USPSTF guidelines recommend against routine screening for women, for instance, while the Kmart-Medtronic program is much more liberal, recommending that a 65 year old woman with no other risk factors except a history of smoking undergo ultrasound. (Everyone agrees that a repair procedure is indicated when ultrasound finds a AAA larger than 5.5 cm.)

Now you might well wonder about the harms associated with screening, especially with a test such as ultrasound, which is entirely noninvasive, and especially when a big company like Medtronic is picking up the tab. In fact, a vascular surgeon who spoke to me on behalf of the coalition told me that ultrasound screening for AAA carries

no risk: ultrasound will not identify people who will end up being treated who should not be treated.  If you have an aneurysm as diagnosed on ultrasound you will benefit if it’s greater than 5 cm or greater. The data are very clear:  there is no overtreatment– once an aneurysm has been identified there is no risk of overtreating or mistreating it.

But the surgeon is wrong. Any screening program and any treatment procedure has both risks and benefits. The surgeons may not like to think about it, but even a life-saving procedure like AAA repair can be harmful if performed in the wrong population. This is why we need an objective and impartial gatekeeper, like the USPSTF. And the USPSTF guidelines are quite clear about this, repeatedly asserting that there are significant dangers associated with inappropriate AAA screening. Here, for example, is what the USPSTF has to say about screening women:

Because of the low prevalence of large AAAs in women, the number of AAA-related deaths that can be prevented by screening this population is small. There is good evidence that screening and early treatment result in important harms, including an increased number of surgeries with associated morbidity and mortality, and psychological harms. The USPSTF concluded that the harms of screening women for AAA outweigh the benefits.

So it turns out that the harms of over-screening are also significant and worthy of concern. I asked Joseph Ross, a researcher at Yale, to help me understand the implications of the Kmart-Medtronic screening program. Ross walked me through the math and  painstakingly demonstrated how a seemingly beneficial screening procedure can actually cause harm. (Note that the numbers he uses are meant to illustrate the general concept and are not intended to represent a precise assessment of AAA screening.)

Here is a way to think about it epidemiologically. If screening has a sensitivity of 95% and a specificity of 99% for AAAs that are greater than 5 cm in diameter, then if there are 1000 high risk individuals undergoing screening (by high risk, I am assuming the population risk for a AAA > 5cm is 10%), then

  • 95 of 100 with AAAs are CORRECTLY identified as having a AAA
  • 5 of 100 with AAA are INCORRECTLY identified as not having a AAA
  • 9 of 900 without AAAs are INCORRECTLY identified as having a AAA
  • 891 of 900 without AAAs are CORRECTLY identified as not having a AAA

So, 104 people undergo repair (of whom 9 didn’t need it), which has pretty substantial risks.

However, now let’s look what happens with a lower risk population — I am now assuming the population risk for a AAA > 5cm is 1% among 100,000 lower risk individuals undergoing screening, then

  • 950 of 1000 with AAAs are CORRECTLY identified as having a AAA
  • 50 of 1000 with AAA are INCORRECTLY identified as not having a AAA
  • 990 of 99,000 without AAAs are INCORRECTLY identified as having a AAA
  • 98,010 of 99,000 without AAAs are CORRECTLY identified as not having a AAA

Clearly, this gets ugly fast. Now 1940 people undergo repair (of whom 990 didn’t need it). That’s a lot of extra stents/surgeries – because when they go in for repair and find a 3.5 cm, rather than a 5 cm, surgeons are unlikely just to close it up. They put in a stent to “stabilize it” and reduce the likelihood of needing full repair – without any evidence.

The only possible defense for expanded screening is that newer  or better data than that available to the USPSTF demonstrate that the benefits of expanded screening in fact outweigh the disadvantages. But the Kmart-Medtronic risk calculator doesn’t provide any explanation for its risk calculations, and it never specifically justifies or explains why it deviates from the USPSTF guidelines.

In other words, Medtronic and the coalition members, entirely on their own, set up their own screening program from which they will all benefit financially. The program has no oversight or peer review and never explains its process or methodology. By contrast, the USPSTF guidelines are created by an independent panel of experts who review the scientific evidence and publish their findings in well-documented publications, with all the evidence on full display for anyone to review.

Not all blue light specials turn out to be a good bargain.

About these ads

8 comments

  1. Larry there are new data on who to screen for AAA. This not an RCT. Can you forward to Dr Joseph Ross?

    Analysis of risk factors for abdominal aortic aneurysm in a cohort of more than 3 million individuals

    K. Craig Kent, MDa, Robert M. Zwolak, MDa, Natalia N. Egorova, PhD, MPHb, Thomas S. Riles, MDa, Andrew Manganaro, MDa, Alan J. Moskowitz, MDb, Annetine C. Gelijns, PhDb, Giampaolo Greco, PhD, MPHb
    Received 17 February 2010; accepted 4 May 2010. published online 14 July 2010.

    Background

    Abdominal aortic aneurysm (AAA) disease is an insidious condition with an 85% chance of death after rupture. Ultrasound screening can reduce mortality, but its use is advocated only for a limited subset of the population at risk.

    Methods

    We used data from a retrospective cohort of 3.1 million patients who completed a medical and lifestyle questionnaire and were evaluated by ultrasound imaging for the presence of AAA by Life Line Screening in 2003 to 2008. Risk factors associated with AAA were identified using multivariable logistic regression analysis.

    Results

    We observed a positive association with increasing years of smoking and cigarettes smoked and a negative association with smoking cessation. Excess weight was associated with increased risk, whereas exercise and consumption of nuts, vegetables, and fruits were associated with reduced risk. Blacks, Hispanics, and Asians had lower risk of AAA than whites and Native Americans. Well-known risk factors were reaffirmed, including male gender, age, family history, and cardiovascular disease. A predictive scoring system was created that identifies aneurysms more efficiently than current criteria and includes women, nonsmokers, and individuals aged <65 years. Using this model on national statistics of risk factors prevalence, we estimated 1.1 million AAAs in the United States, of which 569,000 are among women, nonsmokers, and individuals aged <65 years.

    Conclusions

    Smoking cessation and a healthy lifestyle are associated with lower risk of AAA. We estimated that about half of the patients with AAA disease are not eligible for screening under current guidelines. We have created a high-yield screening algorithm that expands the target population for screening by including at-risk individuals not identified with existing screening criteria.

  2. Thanks, Dan. I’ve forwarded the note to Joe. I also found a nice article in Heartwire on the paper. In truth, I am completely in favor of more and better data to improve screening. What I’m completely opposed to is when a company or other interested group or groups hijacks the process.

  3. Larry, I have found many AAA in patients who would never be candidates based on the USPSTF criteria. I can understand the wariness among many about industry pushing a screening test (kind of like how drug companies advertise on TV for lipitor, huh?). But if it leads to increased detection of a potentially preventable adverse event, together with increased referrals (and therefore better risk factor modification, something that has been documented once AAA has been detected and referred), then I am all for it. Patients should not get stenting or surgery for AAA<5.5 cm unless they have other risk factors for rupture (such as rapid growth in the past year of serial scanning, a family history of rupture, and possibly women and smokers). In most hands they wouldn't. If this leads to harms (and AAA surgery does carry a 5% risk of mortality in good hands), then it's a shame. But compared to the massive underdiagnosis of AAA (ie most ruptured AAA occur in patients with unknown disease who could have been scanned/studied, and most ruptured AAA 85-90% are fatal), I don't think it's such a bad thing. If Pfizer set up a cholesterol-screening tent in K-mart, I don't think people would complain. Erectile dysfunction drug makers are all over questionnaires for detecting ED; Sanofi-Aventis flogs peripheral arterial disease on commercials because clopidogrel was proven beneficial in PAD in the CAPRIE study. etc. etc.

  4. Dan, thanks for passing along. While the study uses a unique data source and is definitely hypothesis generating, in my opinion, the analysis is very limited.
    It’s a retrospective analysis of a cohort of self-referred individuals who paid for the test out of pocket and AAAs were defined as aneurysms ≥ 3cm. To be convincing, the study needs to be prospectively conducted to identify patient characteristics that are associated with AAA, or at least a good retrospective case-control study.
    And even in this analysis, age and smoking status were by far the most important predictors of AAA.
    The purpose of screening is not to identify AAAs; the purpose of screening is to identify AAAs that are likely to have a clinical impact on the patient and are at a stage where they can be intervened upon successfully.
    This study doesn’t get us there.
    Also, my point to Larry was about considering what happens in terms of false-positives when a screening strategy is adopted that includes a lower risk population.
    I only read this article quickly, but these authors’ numbers bear this out as well. In the heart.org story its clarified:
    “Therefore, the authors point out that a decision on which number to use as a threshold score may come down to cost, because a lower threshold score for screening would identify more aneurysms but also require more ultrasound studies as well as follow-up testing. For example, focusing only on the cost of the initial screening test, setting the cutoff at 42 would lead to the identification of 680 000 aneurysms in the population aged 50 to 75, but at the expense of 24 907 000 ultrasound studies. Raising the cutoff to 65 would yield half as many aneurysms but will require only one-fifth as many ultrasound studies.”
    And the numbers would look even worse if they were calculated for a AAA as defined as 5 or 5.5cm, instead of 3cm.

  5. Pingback: Red light or green light for AAA screening? « CardioBrief

  6. Dan Hackman – thank you for your insights!

    A close friend (50 years old) who lives in Northern California suffered a burst aorta last year while on a business trip to New Zealand. Luckily he survived. Recently, Richard Holbrooke was not so lucky.

    The simple truth is that both these men might have benefitted greatly from an advanced AAA screening. The risk of them not getting screened proved fatal or nearly fatal.

    The medical profession’s “Recommended Guidelines” are ALWAYS being revised based on new studies – nothing is ever final or 100% conclusive.

    Thank God! Otherwise, the medical profession would still be recommending leeches!

    Ultrasound is popular with the general public because it is safe and non intrusive.

    Can we have a little more open mindedness on this issue?

    • Agreed. The US screening trials clearly demonstrate reductions in morbidity and mortality. There has not been broad uptake of this evidence even in the groups for whom it has been recommended. Stretching the coverage to capture younger people with smoking histories will detect more cases prior to rupture (now the tenth leading cause of death in the U.S.).

What do you think?

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s