Radiology: Volume 257: Number 2-November 2010
Joseph Shemesh, MD Claudia I. Henschke, PhD, MD Dorith Shaham, MD Rowena Yip, MPH Ali 0. Farooqi, MD Matthew D. Cham, MD Dorothy I. McCauley, MD Mildred Chen, MD James P. Smith, MD Daniel M. Libby, MD Mark W. Pasmantier, MD David F. Yankelevitz, MD
Purpose: To assess the usefulness of ordinal scoring of the visual assessment of coronary artery calcification (CAC) on low-dose computed tomographic (CT) scans of the chest in the prediction of cardiovascular death.
Materials and methods: All participants consented to low-dose CT screening ac¬cording to an institutional review board-approved proto¬col. The amount of CAC was assessed on ungated low-dose CT scans of the chest obtained between June 2000 and December 2005 in a cohort of 8782 smokers aged 40-85 years. The four main coronary arteries were visu¬ally scored, and each participant received a CAC score of 0-12. The date and cause of death was obtained by using the National Death Index. Follow-up time (median, 72.3 months; range, 0.3-91.9 months) was calculated as the time between CT and death, loss to follow-up, or December 31, 2007, whichever came first. Logistic regres¬sion analysis was used to determine the risk of mortality according to CAC category adjusted for age, pack-years of cigarette smoking, and sex. The same analysis to deter¬mine the hazard ratio for survival from cardiac death was performed by using Cox regression analysis.
Results: The rate of cardiovascular deaths increased with an in-creasing CAC score and was 1.2% (43 of 3573 subjects) for a score of 0, 1.8% (66 of 3569 subjects) for a score of 1-3, 5.0% (51 of 1015 subjects) for a score of 4-6, and 5.3% (33 of 625 subjects) for a score of 7-12. With use of subjects with a CAC score of 0 as the reference group, a CAC score of at least 4 was a significant predic¬tor of cardiovascular death (odds ratio [OR], 4.7; 95% confidence interval: 3.3, 6.8; P < .0001); when adjusted for sex, age, and pack-years of smoking, the CAC score remained significant (OR, 2.1; 95% confidence interval: 1.4, 3.1; P = .0002).
Conclusion: Visual assessment of CAC on low-dose CT scans provides clinically relevant quantitative information as to cardiovascular death.