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Updated: May 18, 2026

Identifying Coronary Artery Calcification on Non-gated Computed Tomography Scans
Published on: August 28, 2018
Coronary artery calcium distributions in older persons in the AGES-Reykjavik study
Elias Freyr Gudmundsson1, Vilmundur Gudnason, Sigurdur Sigurdsson
1Icelandic Heart Association, Research Institute, Kopavogur, Iceland.
Insights
Coronary Artery Calcium (CAC) distribution in older adults varies by sex and age. The Zero-Inflated Negative Binomial (ZINB) model best characterized CAC data, outperforming other statistical methods.
Area of Science:
- Cardiology
- Biostatistics
- Epidemiology
Background:
- Coronary Artery Calcium (CAC) indicates advanced atherosclerosis and predicts cardiac events.
- CAC distribution is complex, featuring skewness, zero-inflation, and over-dispersion, posing modeling challenges.
- Understanding CAC distribution is crucial for accurate risk assessment in aging populations.
Purpose of the Study:
- To describe Coronary Artery Calcium (CAC) distributions in an unselected elderly population.
- To compare different statistical modeling methods for characterizing CAC distribution.
- To identify factors associated with CAC in an aging Icelandic cohort.
Main Methods:
- Utilized data from the AGES-Reykjavik study (n=5,764, ages 66-96).
- Applied linear regression (logarithmic and Box-Cox transformations), quantile regression, and a Zero-Inflated Negative Binomial (ZINB) model.
- Compared models using PRESS-statistic, R-squared, and number of detected associations.
Main Results:
- Significant differences in CAC were observed based on sex, age, prior coronary events, and carotid plaque presence.
- Associations between CAC and traditional coronary artery disease (CAD) risk factors differed between sexes.
- The ZINB model demonstrated superior performance in PRESS-statistic, R-squared, and predicting zero scores.
Conclusions:
- The ZINB model is recommended for accurately modeling complex CAC distributions.
- CAC patterns and their associations with risk factors show significant variation within the elderly population.
- Accurate CAC modeling is essential for understanding atherosclerosis progression and cardiac risk.
Abstract:
Coronary Artery Calcium (CAC) is a sign of advanced atherosclerosis and an independent risk factor for cardiac events. Here, we describe CAC-distributions in an unselected aged population and compare modelling methods to characterize CAC-distribution. CAC is difficult to model because it has a skewed and zero inflated distribution with over-dispersion. Data are from the AGES-Reykjavik sample, a large population based study [2002-2006] in Iceland of 5,764 persons aged 66-96 years. Linear regressions using logarithmic- and Box-Cox transformations on CAC+1, quantile regression and a Zero-Inflated Negative Binomial model (ZINB) were applied. Methods were compared visually and with the PRESS-statistic, R(2) and number of detected associations with concurrently measured variables. There were pronounced differences in CAC according to sex, age, history of coronary events and presence of plaque in the carotid artery. Associations with conventional coronary artery disease (CAD) risk factors varied between the sexes. The ZINB model provided the best results with respect to the PRESS-statistic, R(2), and predicted proportion of zero scores. The ZINB model detected similar numbers of associations as the linear regression on ln(CAC+1) and usually with the same risk factors.
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