The association of coronary artery calcium score and mortality risk among smokers: The coronary artery calcium consortium

Background and aims: Cardiovascular disease (CVD) and cancer are the two leading causes of death in smokers. Lung cancer screening is recommended in a large proportion of smokers. We examined the implication of coronary artery calcium (CAC) score (quantitative and qualitative) for cardiovascular disease (CVD), coronary heart disease (CHD), and cancer mortality risk prediction among current smokers. Methods: We included current smokers without known heart disease from the CAC Consortium. Cox regression (for all-cause mortality) and Fine-and-Gray competing-risk regression (for CVD, CHD, and cancer mortality) models, adjusted for traditional CVD risk factors, were used to assess the association between CAC and each mortality outcome, with CAC as a continuous (log2-transformed) or categorical variable (CAC = 0, CAC = 1-99, CAC = 100-399, and CAC 400). We used number of vessels with CAC as a surrogate for the qualitative measure of CAC and mortality outcomes. Analyses were repeated for lung cancer screening-eligible population (defined as ever smokers with > 30 pack years smoking history) (n = 1,149). Hazard ratios (HR) for all-cause mortality and Subdistribution HRs (sHR) with 95% confidence intervals (CI) were reported. Results: Over a median of 11.9 years (25th-75th percentile: 10.2-13.3) of follow-up, of 5,147 current smokers (mean age 52.5 +/- 9.4, 32.4% women) 337 died (102 of CVD, 54 of CHD, and 123 of cancer). A doubling of CAC score was associated with increased HRs of all-cause mortality (1.10 (1.06-1.14)), and sHRs for CVD (1.15 (1.07-1.24)), CHD (1.26 (1.11-1.42)) and cancer mortality (1.06 (1.00-1.13)). Those with CAC >= 400 had increased sHR of CVD (3.55 (1.70-7.41)), CHD (8.80 (2.41-32.10)), and cancer mortality (1.85 (1.07-3.22)), compared with those with CAC = 0. A diffuse CAC pattern significantly increased the risk of all-cause, CVD, and CHD mortality among smokers. Results were consistent for the lung cancer screening-eligible population. Conclusions: Qualitative and quantitative CAC scores can prognosticate risk of all-cause, CVD, CHD, and cancer mortality beyond traditional risk factors among all smokers as well as those eligible for lung cancer screening.