March 4th, 2011

Legislating CVD Screening Tests in Texas

Imaging tests for cardiovascular risk assessment hold great promise.  Both coronary artery calcium (CAC) scanning and carotid intima-media thickness (CIMT) testing have been shown in multiple prospective studies to predict cardiovascular outcomes and, more recently, to improve risk reclassification based upon the Framingham Risk Score.  Coupled with frustrations about the performance of the Framingham Risk Score as well as the movement towards personalized medicine, it is understandable why there is great enthusiasm for broader implementation of these tests.  This enthusiasm has taken tangible form in the Texas Atherosclerosis Imaging Bill, HB 1290, which was passed by the Texas Legislature in 2009 mandating insurance coverage for CAC scanning or CIMT testing every 5 years in an accredited laboratory for men aged between 45 and 75 years and women aged between 55 and 75 years who also have diabetes or “a risk of developing coronary heart disease, based on a score derived using the Framingham Heart Study coronary prediction algorithm, that is intermediate or higher.”

The question is: in our intention to do something, are we sure we know what it is we are doing?  And more importantly, is our understanding of these tests and their full implications for population level implementation at a stage where legislative action is warranted? In a recent editorial, I tried to address these issues by taking a closer look at Texas HB 1290.

While some have argued that legislative coverage mandates are never warranted, there are some prerequisite questions that should reasonably be asked before considering such tools: How many people will this affect?  What are the costs?  What are the risks?  How many lives can we save or CVD events can we prevent?  Is there agreement on how to use these tests and interpret the results?  What do the experts say about how we should use these tests? What do patients think? Insurers? Public health officials?

To the extent that these data are available in public testimony and records, it seems that most of these questions were either not addressed or not in sufficient detail commensurate with such a novel bill with broad implications.  In my calculations, if all people in the designated age range and risk category specified by the bill were scanned, this group would comprise 2.4 million individuals with an initial cost of $480 million.  Those are astounding figures that alone should give us pause to ask “what are we getting in return?” To be sure, there would almost certainly be a large number of patients at high risk for CVD events who would be detected (~285,000 by my calculations), and intensifying preventive therapies in this group may globally improve cardiovascular outcomes.

However, this later point has several caveats.  First of all, the majority of patients in age and risk category would already have an indication for statin therapy, and it is unclear what additional benefit is gained from intensification of statins in primary prevention.  In addition, as we move closer to “treat all” (as we are likely to see additional groups recommended for lipid lowering therapy in the upcoming ATP IV), the utility of these tests from a population level are diminished. Finally, the reduction in CV events would have to be balanced against the radiation risks and incidental findings in this asymptomatic population.  It is possible (or even probable) that these atherosclerosis imaging tests would still end up favorable, but these calculations were certainly warranted before seeking a legislative mandate.

Many detractors of atherosclerosis imaging tests have focused on the lack of randomized clinical trials evaluating the impact of these tests on improving clinical outcomes.  While a critical point, there are several other more proximal issues that need to be clarified before pondering a legislative mandate.  For example, the “intermediate risk” group is a very logical target based upon a Bayesian approach, but this group can be defined in many different ways.  Just shifting this group from 10-20% 10-year risk to 6-20% 10-year risk would add several hundred thousand additional Texans for screening eligibility.  In addition, focusing on the 10-20% risk group would shortchange the potential utility of these scans in women as there are few “intermediate risk” women in the population, and more than four times as many men compared with women are eligible for atherosclerosis imaging under HB 1290.  In addition, there is still no universal consensus on the appropriate interpretation of and response to specific test results.  In my personal practice, I have assumed the care of patients that were previously treated as if they have a “disease” when they have small amounts of coronary calcium at a younger age, and others who were told they were just fine with the same findings.

I have two disclosures for this blog: 1) I am a Texan 2) I order coronary artery calcium scans.  For the former, I felt the need to look closely at this legislation to evaluate its global ramifications for people in this state.  For the latter, I have detailed discussions with each patient about the risks and benefits and how we may change our management based upon the results before we order these tests. But the leaps of evidence and understanding required for individual patient-doctor decisions, to population screening, to legislative mandates are vast and we must tread carefully before we invoke legislative action.

3 Responses to “Legislating CVD Screening Tests in Texas”

  1. William Burke, MD says:

    Screening in general is a tricky business. You need to consider false positives and negatives in anddition to the true tests. It is important to consider the negative consequences of the test itself. The radiation burden from CAC is not insignificant.Are there other tests alone or in combination that have a predictive value that is comparable or better than these tests. Who gets the bill? In the total health system does this expenditure take resources from other proven tests, treatments or prevention measures. I think theTexas legislators have acted prematurely.

  2. The radiation burn from CAC is insignificant. At 0.7 msv for EBT-CC and 3-5 msv for helical CAC, it in inconsequential compared to a nuclear stress test or PET stress. Mammography is 0.7 msv. If we can justify this for breast cancer, how can we not justify it for coronary disease detection which kills 6 times more women than breast cancer.

  3. Fahim H Jafary, MD, FACC, FSCAI says:


    Actually with modern scanners like the Seimens 256 slice dual source, the radiation dose for a FULL cardiac CTA (not just a calcium score) is < 1 msv. The lowest I've done is 0.2 msv although admittedly you have to be quite thin for that. Bulkier patients may push the dose to < 2 msv – still very low.

    I fully favor screening for CAD – as you said, we screen for many other diseases so why not the top killer of all. The reason why CTA based screening gets such a bad rap is because of what happens AFTER the test if disease is found – inevitably a cath and a stent in an asymptomatic patient WITHOUT any objective assessment of ischemic burden. What SHOULD follow is a functional study and medical therapy for the majority who'll have either no ischemia or mild-moderate medically treatable silent ischemia, reserving cath and revasc. for those with a high ischemic burdens. Where's the evidence? No direct trials (I suspect there probably never will be one because of lack of clinical equipoise ….. would you randomize your patient with substantial plaque to no therapy?) but evidence from the primary preventive literature suggests that high risk individuals benefit from statin therapy – so by extension so should those with subclinical atherosclerosis.

    Calcium scoring is a great tool, though now that radiation exposures are so low, one can also do a full CTA. We see many patients with significant atherosclerosis yet astounding calcium scores of zero. There is a bit of a dye exposure though, plus the inconvenience so as a mass screening program full CTA might be difficult. Cost effectiveness will remain a separate question as is the question of whether or not people will change habits after knowing that they have CAD.

    Competing interests pertaining specifically to this post, comment, or both:
    I’m an interventional cardiologist and turn down caths in asymptomatic folks referred to the lab after CTA without functional testing.