Coronary Artery Calcium for the Prediction of Mortality in Young Adults 75 Years Old
Does coronary artery calcium (CAC) scoring predict mortality among asymptomatic young adults and elderly adults?
Data from three centers (in Torrance, CA; Columbus, OH; Nashville, TN) were included in this analysis. All scans were completed between 1991 and 2004, and used a common scanning protocol. Patients were asymptomatic and without apparent cardiovascular disease (CVD) at the time of the CAC scans, which were ordered for CV risk stratification by their primary care providers. All-cause mortality rates were calculated after stratifying by age groups (<45, 45–54, 55–64, 65–74, and ≥75 years) and CAC score (0, 1–100, 100–400, and >400). Multivariable Cox regression models were constructed to assess the independent value of CAC for predicting all-cause mortality in the <45- and ≥75-year-old age groups.
A total of 44,052 patients were included in this analysis. The mean age of the study population was 54.4 ± 10.7 years. Males comprised 54% of the study population, 37% of patients had a family history of premature coronary heart disease (CHD), and 14% were smokers. Diabetes mellitus, hypertension, and dyslipidemia were present in 5%, 24%, and 30% of the study population, respectively. The proportion of patients with hypertension, diabetes mellitus, and dyslipidemia increased significantly with the increasing age group, whereas the prevalence of tobacco use or a positive family history of CHD decreased with increasing age. The mortality rates increased in both the <45- and ≥75-year-old age groups with an increasing CAC group. After multivariable adjustment, increasing CAC was independently predictive of increased mortality compared with CAC = 0. For those <45 years, the hazard ratios were 2.3 (95% confidence interval [CI], 1.2-4.2) for CAC scores between 0 and 100; hazard ratio (HR), 7.4 (95% CI, 3.3-16.6) for CAC scores between 100 and 400; and HR, 34.6 (95% CI, 15.5-77.4) for CAC scores >400. For those patients ages 75 years or older, the HRs were 7.0 (95% CI, 2.4-20.8) for CAC scores between 0 and 100; HR, 9.2 (95% CI, 3.2-26.5) for CAC scores between 100 and 400; and HR, 16.1 (95% CI, 5.8-45.1) for CAC scores >400. Persons <45 years old with a CAC score between 100 and 400 had a twofold increase in mortality rates compared to persons ≥75 years with no CAC. For the same age group, those with a CAC score >400 had a 10-fold increase in mortality compared to those ≥75 years with no CAC. Individuals ≥75 years old with CAC = 0 had a 5.6-year survival rate of 98%, similar to those in other age groups with CAC = 0 (5.6-year survival, 99%).
The investigators concluded that CAC is associated with risk of mortality for elderly patients and patients 45 years of age. Elderly patients with no CAC have a lower risk for mortality compared to younger patients with high levels of CAC.
These data suggest that CAC may be a predictor of mortality among young adults as well as those over 75 years of age. As the authors state, these data are subject to referral bias. Understanding how CAC may add to current risk prediction, which is based on age and CVD risk factors, is warranted.
Keywords: Pyrenes, Incidence, Coronary Artery Disease, Survival Rate, Cardiovascular Diseases, Calcinosis, Coronary Disease, Risk Factors, Hypertension, Primary Health Care, Diabetes Mellitus
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