Editorials
Is There Benefit to Coronary Calcium Screening?
See related article on page 1219.
Risk assessment and targeted risk factor modification are critical to the disease prevention paradigm in family medicine. Because coronary artery disease (CAD) represents the leading cause of death in the United States, prevention efforts have tremendous potential to reduce disease morbidity and mortality on a population scale.
In this issue of AFP, Mieres and colleagues1 discuss the potential role of noninvasive cardiac imaging technologies in estimating a patient's risk of a future myocardial infarction. In symptomatic patients, single-photon emission computed tomography myocardial perfusion scans and stress tests have a fairly high sensitivity and specificity and have proven to be useful in clinical decision making. In asymptomatic patients, however, the role of these tests is much more complicated. Currently, there is no evidence that electrocardiography, stress echocardiography, or cardiac computed tomography (CT) improves health outcomes in low-, intermediate-, or high-risk persons; application of such screening to the general, low-risk population may be harmful.2
The Framingham risk calculator is useful for stratifying patients into low-, intermediate-, and high-risk categories based on age, sex, lipid levels, presence of hypertension, and smoking status.
Unfortunately, a large group of asymptomatic patients falls into the intermediate-risk category (10 to 20 percent 10-year risk of CAD). It would be useful if these patients could be "bumped down" into the low-risk category to be reassured, or "bumped up" into the high-risk category to be prescribed more aggressive medical management (e.g., treatment to reduce a low-density lipoprotein or blood pressure goal, chemoprophylactic aspirin administration) or possibly have invasive interventions (e.g., coronary catheterization, bypass) if such interventions were to prove beneficial. For this to happen, there needs to be either a more refined understanding of the meaning of the intermediate-risk category or new methods of risk assessment, beyond what is already included in the Framingham calculator, that can more definitively sort persons into the "reassure" or "vigorous risk reduction" treatment categories.
For CAD risk stratification or a screening test to aid in the evaluation of asymptomatic, intermediate-risk patients, it must answer the following three questions. Does the test independently predict coronary events beyond Framingham risk scoring alone? Does a positive test occur often enough in those at highest risk of CAD to make mass application worth it (i.e., sufficient yield)? Do patients identified as high risk by the test stand to benefit from therapy? If the answer to any of these questions is uncertain, there is no way to know if applying such a test to large populations of asymptomatic patients would be beneficial. Even with adequate data to answer these questions, the test actually could be harmful by causing false-positive results, providing false reassurance, or by labeling persons with a disease when interventions are not effective.
Cardiac CT (or electron beam CT) is one of the most promising noninvasive technologies for screening asymptomatic, intermediate-risk patients. Coronary calcium scores are independent predictors of CAD (especially at values over 400), reliability is good, and population-based studies have shown that high scores are seen in a large proportion of intermediate-risk patients.3-6 However, it remains uncertain whether changes in the treatment of patients restratified as high risk based on coronary calcium scores improve clinical outcomes. For example, statins have not been shown to decrease mortality in patients screened with cardiac CT, and there is even conflicting evidence about whether they produce the intermediate outcome of reduction in coronary calcium scores.7,8
In October 2006, the American Heart Association (AHA) released a scientific statement encouraging Framingham risk assessment in asymptomatic persons and advising against the use of coronary calcium assessment in asymptomatic persons at low risk (less than 10 percent 10-year risk) and high risk (over 20 percent 10-year risk). It also states that in clinically selected intermediate-risk patients, it may be reasonable to measure the atherosclerotic burden using electron beam CT or multidetector CT to refine clinical risk prediction and to select patients for more aggressive target values for lipid-lowering therapies.9 Although some may interpret this to be a green light for cardiac CT in the intermediate-risk group, the recommendation is a class IIb recommendation, which means that there is conflicting evidence or a divergence of opinion about the usefulness or effectiveness of a procedure or treatment where usefulness or effectiveness is less well established by evidence or opinion. The AHA acknowledges in this statement that there are no outcome studies demonstrating that measurement of coronary calcium leads to improved outcomes.9
The U.S. Preventive Services Task Force is currently developing its recommendation statement for the use of nontraditional risk factors in intermediate-risk persons. It will include a review of coronary calcium assessment, as well as other risk factors (e.g., high-sensitivity C-reactive protein, ankle-brachial index, white blood cell count, fasting blood glucose, periodontal disease, carotid intimal thickness, homocysteine, lipoprotein [a]).
The bottom line is that the jury is still out on how noninvasive testing could or should be used to restratify asymptomatic patients at intermediate risk of CAD. Cardiac CT is expensive ($400 to $500 per scan) and thus far has not been proven to affect patient-oriented outcomes. Until further research is available, current evidence indicates that physicians should not order cardiac CT as a screening test in asymptomatic patients.
The authors of this article are responsible for its contents, including any clinical or treatment recommendations. No statement in this article should be construed as an official position of the Agency for Healthcare Research and Quality or the U.S. Department of Health and Human Services.
Address correspondence to Janelle Guirguis-Blake, M.D., at jguirgui@u.washington.edu. Reprints are not available from the authors.
Author disclosure: Nothing to disclose.
REFERENCES
1. Mieres JH, Redberg RF, Shaw LJ. Noninvasive coronary imaging. Am Fam Physician 2007;75:1219-28.
2. U.S. Preventive Services Task Force. Screening for coronary heart disease: recommendation statement. Ann Intern Med 2004;140:569-72.
3. Pletcher MJ, Tice JA, Pignone M, Browner WS. Using the coronary artery calcium score to predict coronary heart disease events: a systematic review and meta-analysis. Arch Intern Med 2004;164:1285-92.
4. Greenland P, LaBree L, Azen SP, Doherty TM, Detrano RC. Coronary artery calcium score combined with Framingham score for risk prediction in asymptomatic individuals [Published correction appears in JAMA. 2004;291:563]. JAMA 2004;291:210-5.
5. Vliegenthart R, Oudkerk M, Hofman A, Oei HH, van Dijck W, van Rooij FJ, et al. Coronary calcification improves cardiovascular risk prediction in the elderly. Circulation 2005;112:572-7.
6. Arad Y, Goodman KJ, Roth M, Newstein D, Guerci AD. Coronary calcification, coronary disease risk factors, C-reactive protein, and atherosclerotic cardiovascular disease events: the St. Francis Heart Study. J Am Coll Cardiol 2005;46:158-65.
7. Achenbach S, Ropers D, Pohle K, Leber A, Thilo C, Knez A, et al. Influence of lipid-lowering therapy on the progression of coronary artery calcification: a prospective evaluation. Circulation 2002;106:1077-82.
8. Arad Y, Spadaro LA, Roth M, Newstein D, Guerci AD. Treatment of asymptomatic adults with elevated coronary calcium scores with atorvastatin, vitamin C, and vitamin E: the St. Francis Heart Study randomized clinical trial. J Am Coll Cardiol 2005;46:166-72.
9. Budoff MJ, Achenbach S, Blumenthal RS, Carr JJ, Goldin JG, Greenland P, et al. Assessment of coronary artery disease by cardiac computed tomography: a scientific statement from the American Heart Association Committee on Cardiovascular Imaging and Intervention, Council on Cardiovascular Radiology and Intervention, and Committee on Cardiac Imaging, Council on Clinical Cardiology. Circulation 2006;114:1761-91.
Close-ups: Introducing a New Feature
See related department on p. 1177.
In this issue we introduce "Close-ups: A Patient's Perspective," a feature that focuses on the personal side of medicine. The major component of this feature is a patient's story, told in his or her own words. In these stories, patients speak about the challenges they face in illness and recovery, and reflect on the support they have received along the way. Eighty-three-year-old E.S. in this issue, for example, tells of the difficulties he and his wife have encountered since she was paralyzed by a stroke.1
Because family physicians often closely participate in the process of illness and recovery, the feature will include, when possible, a section with the physician's thoughts and comments. A third component of the new feature is an image; this may be a photograph of the patient or of something meaningful to him or her, such as a favorite animal or garden scene. Finally, as practice pointers, the feature lists possible resources such as Web sites or organizations.
Why have such a feature? A recent study of general practitioners in the United Kingdom found that the most satisfying aspect of their work was using their knowledge of individual patients to achieve the most successful outcomes.2 The basis of this knowledge goes beyond the factual to include an understanding of the patients' behavior and psychosocial context. Ultimately, the study showed that satisfaction was most closely related to the perceived quality of the physicians' personal relationships with their patients. The need to connect with patients may be more important than ever in an age that presents so many challenges to meaningful practice.
Another study showed that physician dissatisfaction was associated with the day-to-day challenges of running a business, keeping up with technologic advances, protecting the scope of practice, and managing precious time.3 In addition to these office-based challenges, physicians live in a health care environment that continually raises difficult issues, many of them of a magnitude that transcends our personal practices: uninsured patients, a fragmented health care system, epidemics of obesity and lung disease, the threat of bioterrorism, contentious issues such as abortion, and rising health care costs. For anyone overwhelmed by contemporary health care developments, going back to our roots-meaningful, healing relationships with the people and communities we care for-might put our daily practice into perspective. Close-ups offers an intimate, personal reminder of this most important task.
Close-ups is a collective enterprise. Our readers are encouraged to speak with their patients and submit their stories and photographs. By adding their own reflections, physicians can share the countless ways in which these patients have inspired them. Patients can provide a recorded or written story, which will have a final length of about 250 words. Photographs can be obtained in the office or patients can select their own, but they must be of sufficient quality for publication (i.e., a resolution of at least 300 dpi).
We look forward to sharing these vignettes with our readers, reminding us that our patients are the heart of what we do.
EDITOR'S NOTE: Physicians interested in submitting a story for the Close-ups department should contact the author at the address below.
Address correspondence to Caroline Wellbery, M.D., at wellberc@georgetown.edu. Reprints are not available from the author.
REFERENCES
1. A fall in the dark. Am Fam Physician 2007;75:1177.
2. Fairhurst K, May C. What general practitioners find satisfying in their work: implications for health care system reform. Ann Fam Med 2006;4:500-5.
3. Van Ham I, Verhoeven AA, Groenier KH, Groothoff JW, De Haan J. Job satisfaction among general practitioners: a systematic literature review. Eur J Gen Pract 2006;12:174-80.
| Copyright © 2007 by the American
Academy of Family Physicians. |
