Correspondence
Coronary Calcium Screening
N Engl J Med 2009; 361:2490-2492December 17, 2009
- Article
To the Editor:
Bonow (Sept. 3 issue)1 discusses the potential benefits and disadvantages of coronary calcium screening in an asymptomatic population. He highlights his discussion with an example of a patient in whom the calculated Framingham risk score is low (i.e., <10% risk of a coronary event over 10 years). If one applies a more comprehensive risk calculator such as QRISK2,2 the patient's calculated 10-year risk would be approximately 15%. The patient would therefore be in the intermediate-risk group — exactly the sort of patient in whom there may be the greatest benefit from coronary calcium screening. Physicians should be careful when using risk scores that omit important cardiac risk factors such as family history.
2 ReferencesAndrew R.J. Mitchell, M.D.
Jersey General Hospital, Jersey, Channel Islands
an.mitchell@health. gov. je 1
Bonow RO . Should coronary calcium screening be used in cardiovascular prevention strategies? N Engl J Med 2009;361:990-997
Full Text | Web of Science | Medline2
Hippisley-Cox J ,Coupland C ,Vinogradova Y , et al. Predicting cardiovascular risk in England and Wales: prospective derivation and validation of QRISK2. BMJ 2008;336:1475-1482
CrossRef | Web of Science | Medline
To the Editor:
Bonow does not address two issues that make the vignette in his article more challenging: the patient requested a coronary-artery calcium (CAC) scan, and CAC scans are expensive.
Unfortunately, patients' requests for expensive tests have become more common,1 and building long-term, trusting relationships with patients has become more difficult.2 Bonow recommends aspirin, a statin, and exercise, but he advises against a CAC scan. What if the patient responds, “Thanks, Doc, but I'm not worried about radiation and I really don't want to take those drugs or exercise if my coronaries are clean”? Should his doctor order a scan? Bonow does not discuss the cost of CAC scanning, nor who would pay for it; he only discusses the medical risks and benefits. But surely the cost of the test must enter into any rational decision about whether to recommend it.3 As long as that topic remains taboo, we ignore a proverbial elephant in the examination room.
3 ReferencesThomas B. Newman, M.D., M.P.H.
Mark J. Pletcher, M.D., M.P.H.
University of California, San Francisco, San Francisco, CA
newman@epi.ucsf. edu 1
Lee TH ,Brennan TA . Direct-to-consumer marketing of high-technology screening tests. N Engl J Med 2002;346:529-531
Full Text | Web of Science | Medline2
Treadway K . The future of primary care: sustaining relationships. N Engl J Med 2008;359:2086-2088
Full Text | Web of Science | Medline3
Newman TB, Kohn MA. Evidence-based diagnosis. Cambridge, United Kingdom: Cambridge University Press, 2009:52-67.
Author/Editor Response
Mitchell points out that there are methods other than the Framingham risk score for assessing the risk of coronary events, including comprehensive scoring systems that incorporate family history. The Framingham investigators determined that family history did not yield sufficient incremental risk to be included in the Framingham risk score. However, the importance of family history is supported by a number of prospective studies summarized in the report by the Adult Treatment Panel III (ATP III) of the National Cholesterol Education Program,1 which concluded that a family history of premature coronary heart disease is an independent risk factor even when other established risk factors are considered. The ATP III guidelines recommend the use of family history as one of the four risk factors (along with cigarette smoking, low levels of high-density lipoprotein cholesterol, and hypertension) in the initial evaluation to identify persons with multiple risk factors. When a person has two or more of these factors, an estimation of the 10-year risk based on the Framingham risk score is then recommended. Thus, current national guidelines do use the family history.
The patient in the case vignette had a questionable familial predisposition to premature coronary heart disease, since his father, who died at 45 years of age, was a heavy smoker. Nonetheless, in view of the family history and his hypercholesterolemia, treatment with aspirin and a statin was initiated. How would coronary calcium imaging provide additional information that would change this recommendation? Even a coronary calcium score of zero would not completely eliminate the risk of future events.2 Among the subjects in the Multi-Ethnic Study of Atherosclerosis (ClinicalTrials.gov number, NCT00005487) who ultimately underwent coronary angiography for clinical indications,2 11 of 176 subjects (6.2%) with at least one coronary artery with more than 50% stenosis had a calcium score of zero. Up to 17.9% of individual coronary arteries with a significant plaque burden (>50% stenosis) had calcium scores of zero.
Newman and Pletcher are correct that the cost of testing (and the related downstream costs) is another consideration that needs to be brought into the discussion. However, since even “clean coronaries” on a calcium scan would not change the recommendations in this patient, the test would not be cost-effective at any level of cost.
It is uncertain whether coronary calcium imaging is warranted based on either a positive family history of premature coronary heart disease or an intermittent level of risk based on risk scores, as suggested by Mitchell. There are no data showing improved health outcomes or cost-effectiveness with this approach. This represents a hypothesis worth testing, but it should be tested before it becomes a matter of public health policy.
2 ReferencesRobert O. Bonow, M.D.
Northwestern University Feinberg School of Medicine, Chicago, IL
r-bonow@northwestern.edu 1
Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults
CrossRef | Web of Science2
Rosen BD ,Fernandes V ,McClelland RL , et al. Relationship between baseline coronary calcium score and demonstration of coronary artery stenosis during follow-up MESA (Multi-Ethnic Study of Atherosclerosis). JACC Cardiovasc Imaging 2009;2:1175-1183
CrossRef | Web of Science
