JACC Feature: Seeing calcium scans leads to better health
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| Coronary calcium is visible as white spots. Image source: Ann Rheum Dis 2003;62:846-850 |
Coronary artery calcium (CAC) scanning has been shown to predict adverse clinical events, but its direct impact on future coronary artery disease (CAD) risk and downstream medical costs, relative to that of conventional medical practice, has not been studied, according to the researchers, led by Alan Rozanski, MD, from St. Luke's Roosevelt Hospital in New York City.
To gather the necessary data, Rozanski and colleagues initiated the EISNER (Early Identification of Subclinical Atherosclerosis by Noninvasive Imaging Research) trial.
Researchers assigned 2,137 volunteers in a 2:1 ratio to groups that either underwent or did not undergo CAC scanning before risk factor counseling. The primary endpoint was four-year change in CAD risk factors and Framingham risk score (FRS). They also compared the groups for differences in downstream medical resource utilization. The estimated radiation dose of the noncontrast CT calcium scan ranged from 1 to 2 mSv.
At the baseline examination, a nurse practitioner conducted a private risk factor counseling session, explaining the results of subjects' seven modifiable risk factors: blood pressure, cholesterol and triglyceride profiles, blood sugar, weight, waist circumference, exercise and smoking.
Participants also received information on how to improve their risk profiles. In addition, the nurse practitioner reviewed the CAC images, and CAC score and percentile score with subjects in the scanned group. Subjects were instructed that the presence of any calcium constituted evidence of atherosclerosis.
Compared with the no-scan group, the scanned group showed a net favorable change in systolic blood pressure, low-density lipoprotein cholesterol and waist circumference for those with increased abdominal girth. The scanned group also lost more weight among the overweight subjects.
Patients who had normal baseline scans had fewer tests and procedures in the subsequent four years, compared to patients who did not have scans. Drug costs were 7 percent higher in the scanned group because more of these patients started taking blood pressure and cholesterol medications.
In addition, the FRS in the scanned group remained unchanged, but increased in the no-scan group. "The Framingham risk score goes up with age. The fact that it didn't in the scanned group means that they must have taken better care of their health in terms of blood pressure and lipid level control," senior author Daniel S. Berman, MD, chief of cardiac imaging and nuclear cardiology at the Cedars-Sinai Heart Institute in Los Angeles, said in an interview.
"People who were scanned were more motivated to improve their health," Berman said.
Within the scanned group, increasing baseline CAC score was associated with a proportionally greater improvement in most CAD risk factors at follow-up.
There was no significant difference between the two groups with respect to levels of HDL cholesterol, triglycerides and glucose, as well as in smoking cessation and new exercise activity.
"Changing lifestyle is more difficult," Berman said. "We were happy to see a decrease in waist circumference in the scanned group, even though there was no change in their exercise activity."
Many people are unaware of how much they can improve their health simply through treatment, Berman said. In fact, 90 percent of MIs can be avoided by modifying risk factors.
"The goal is for people to receive treatment when it can make a difference. We want to prescribe the right medications, help them implement steps that will change their lifestyle. We think calcium scoring testing could save thousands of lives."