Abstract 14321: Comparing Zero Coronary Artery Calcium With Other Negative Risk Factors for Coronary Heart Disease - Multi-Ethnic Study of Atherosclerosis (MESA)
Background: Less attention is paid to negative coronary heart disease (CHD) risk factors despite their potential public health importance. With emphasis on imaging tests, whose high sensitivity makes them most valuable for “ruling out” disease, we compared Framingham-adjusted negative likelihood ratios (NLRs) for tests commonly used for refining traditional risk estimates.
Methods: MESA is a longitudinal, population-based study of 6,814 men and women aged 45-84 free of clinical cardiovascular disease at enrollment. Median follow-up of the cohort is 5.8 years. According to the method of Gu and Pepe (2009), we calculated multivariable-adjusted NLRs by comparing model coefficients from Framingham Risk Score (FRS)-adjusted logistic regression models before and after the addition of an additional prognostic test. The FRS was calculated using the equation published in Circulation 1998.
Results: A total of 278 participants (4.1%) experienced a CHD event during follow-up. As shown in the figure, a coronary artery calcium (CAC) score of zero is associated with the most reassuring NLR of any test, with a significantly lower NLR than that associated with low hsCRP (p<0.001). The NLR for CAC=0 was remarkably stable across diverse clinical situations, ranging from 0.29 for low risk patients (FRS 0-6%) to 0.24 for intermediate risk individuals (FRS 10-20%). Age was the most significant modifier of the NLR, ranging from 0.41 for intermediate-risk individuals age 45-55 to 0.23 for age >65. Importantly, a finding of CAC=0 is common, with ∼50% of all MESA participants having zero CAC.
Conclusion: FRS-adjusted likelihood ratios represent an intriguing methodology for expressing the strength of negative CHD risk factors. Of the available tests, zero CAC has superior test characteristics, with negative likelihood ratios consistently in the clinically helpful range. Other tests, particularly hsCRP, provide significantly less reassurance when negative.
- © 2011 by American Heart Association, Inc.