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Value of EBT in Assessing Cardiovascular Risk

Am Fam Physician. 2004 Jan 1;69(1):192-193.

Electron beam tomography (EBT) is a validated tool for predicting cardiovascular risk and may be useful, as one retrospective survey showed, in motivating patients to modify unhealthy lifestyle behaviors. O'Malley and colleagues performed a randomized controlled trial to determine whether showing patients an image of their coronary anatomy would be more motivating than intensive case management or usual care.

Among 39- to 45-year-old eligible active-duty U.S. Army personnel, 450 patients were randomized to four study arms—those who were shown their EBT results and received intensive case management or usual care, and those who were not shown their results and had intensive case management or usual care. All patients received cardiovascular risk assessment to predict 10-year cardiovascular risk, using the Framingham risk score, at baseline and after one year.

Patients who were shown their EBT results received a standardized explanation of the relationship between calcification and atherosclerotic disease and resulting coronary heart disease risk, with counseling adapted to the presence or absence of calcifications. Usual care risk-factor modification involved general counseling about diet, smoking, and exercise, with referrals given to the patient's primary care physician, a dietitian, or a smoking cessation program, as appropriate. Intensive case management involved frequent nurse and dietitian contact tailored to each patient's stage of behavior change. In this program, mail, telephone, and visit follow-up were frequent. The primary outcome variable was change in the 10-year predicted event rate (Framingham risk score at one year).

The mean age of the 406 participants who completed the study was 42 years, 79 percent were men, and 15 percent had coronary calcifications. The mean 10-year predicted coronary heart disease risk was 5.85 percent, but at least 75 percent of the cohort had one or more modifiable heart disease risk factor. The group that received EBT results had a mean risk score change of 0.30 percent after one year; in the group that did not receive EBT results, the mean risk score change was 0.36 percent (P = .81). In the group that received intensive case management, the mean risk score change was –0.06 percent versus 0.74 percent in those who did not receive intensive case management (P = .003). Those who received informed EBT with intensive case management had a mean change of –0.057 percent; the EBT group without intensive case management had a mean change of 0.63 percent. The intensive case management group without information had a change of –0.058 percent, and the usual care group without EBT had a change of 0.86 percent (P = .03).

There was no difference in Framingham risk score improvement in the 157 patients who improved their risk status after one year when the EBT-informed group was compared with the noninformed group. More of the patients receiving intensive case management improved than those who did not.

The results of this study suggest that adding EBT to counseling efforts does not change coronary heart disease risk. These findings refute the idea that demonstrated proof of risk would provide an emotionally motivating component to counseling, the so-called teachable moment. The absolute risk reduction in projected 10-year risk for intensive case management was 0.8 percent, or a relative risk reduction of 17 percent, and the number needed to treat for one year equaled 125. The authors speculate that imaging tests might have greater motivational impact in a higher-risk population.

O'Malley PG, et al. Impact of electron beam tomography, with or without case management, on motivation, behavioral change, and cardiovascular risk profile. A randomized controlled trial. JAMA. May 7, 2003;289:2215–23.

editor's note: This article returns risk-factor management to the arena of primary care. It is true that methods of calculating risk factors show considerable variation.1 EBT may be a more direct measure of coronary artery disease than age, but patients may perceive it to be less directly modifiable than obesity, hyperlipidemia, and elevated blood pressure, just as age is not modifiable. Whatever the reason, EBT was not additionally effective in motivating patients, so it does not warrant the additional cost. To the extent that EBT is offered and patients request it, it will continue to play a role in risk-factor assessment in some settings. In particular, patients may ask for it to be given a clean bill of health. A negative result might in fact encourage continuation of unhealthy dietary and other lifestyle behaviors.—C.W.

 

REFERENCE

1. Broedl UC, Geiss HC, Parhofer KG. Comparison of current guidelines for primary prevention of coronary heart disease. J Gen Intern Med. 2003;18:140–5.


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