Coronary Artery Calcium (CAC) Score for Cardiovascular Risk Stratification in a Thai Clinical Cohort: A Comparison of Absolute Scores and Age-Sex Specific Percentiles

Purpose This study aims to examine the prevalence and CAC distribution and to evaluate the association of each CAC classifications with major adverse cardiovascular event (MACE). Method This study was a retrospective observational cohort. We included patient aged above 35 years who underwent CAC testing. The absolute and age-sex specific percentile classification were categorized as 0, 1 to 10, 11 to 100, 101 to 400, and > 400 and 0, < 75th, 75th – 90th, and > 90th, respectively. The end point was MACE, including cardiovascular death, myocardial infarction, heart failure hospitalization, coronary artery revascularization procedures, and stroke. Multivariable Cox regression was used to estimate the hazard ratios. The discriminative performance between classification were compared using Harrell’s C-statistic. The agreement was assessed via Cohens’ Kappa. Result The study included 440 patients, with approximately 70% of Thai patients exhibiting a CAC score. CAC distributed higher in male than female and older than younger. Both CAC classification demonstrated the acceptable predictive performance. However, fair agreement was observed between classifications (Cohen’s kappa 0.51 95%CI 0.42–0.59). Within an absolute classification, the higher CAC could capture the higher hazard ratio more consistently across age-sex specific percentile level. In contrast, the association between MACE and the age-sex specific percentile classification was not consistent in all levels of the absolute CAC scale. Conclusion Both absolute and age-sex-specific percentile CAC scores showed acceptable performance in predicting MACE. However, it is likely that the classification of absolute CAC scores may be more appropriate for risk stratification in Thai clinical cohort.