title: Relationship of Coronary Calcium on Standard Chest CT Scans With Mortality.
abstract: OBJECTIVE
  The aim of this study was to determine the correlation between coronary artery calcium (CAC) scores on 3 mm electrocardiography (ECG)-gated computed tomography (CT) scans and standard 6 mm chest CT scans, and to compare relative strength of associations of CAC on each scan type with mortality risk.
  
  
  BACKGROUND
  Coronary artery calcification predicts cardiovascular disease (CVD) and all-cause mortality, and is typically measured on ECG-gated 3 mm CT scans. Patients undergo standard 6 mm chest CTs for various clinical indications much more frequently, but CAC is not usually quantified. To better understand the usefulness of standard chest CTs to quantify CAC, we conducted a case-control study among persons who had both scan types.
  
  
  METHODS
  Between 2000 and 2003, 4,544 community-living individuals self- or physician-referred for "whole-body" CT scans, had 3 mm ECG-gated CTs and standard 6 mm chest CTs, and were followed for mortality through 2009. In this nested case-control study, we identified 157 deaths and 494 controls frequency matched (1:3) on age and sex. The Agatston method quantified CAC on both scan types. Unconditional logistic regression determined associations with mortality, accounting for CVD risk factors.
  
  
  RESULTS
  Participants were 68 ± 11 years of age and 63% male. The Spearman correlation of CAC scores between the 2 scan types was 0.93 (p < 0.001); median CAC scores were lower on 6 mm CTs compared to 3 mm CTs (22 vs.104 Agatston units, p < 0.001). Adjusted for traditional CVD risk factors, each standard deviation higher CAC score on 6 mm CTs was associated with 50% higher odds of death (odds ratio: 1.5; 95% confidence interval: 1.2 to 1.9), similar to 50% higher odds on the 3 mm ECG-gated CTs (odds ratio: 1.5; 95% confidence interval: 1.1 to 1.9).
  
  
  CONCLUSIONS
  CAC scores on standard 6 mm chest CTs are strongly correlated with 3 mm ECG-gated CTs and similarly predict mortality in community-living individuals. Chest CTs performed for other clinical indications may provide an untapped resource to garner CVD risk information without additional radiation exposure or expense.
authors.affiliation: Department of Orthopaedic Surgery, School of Medicine, University of California, San Diego, California; Department of Family Medicine and Public Health, School of Medicine, University of California, San Diego, California.
authors.forename: Jan M
authors.initials: JM
authors.lastname: Hughes-Austin
authors.affiliation: Department of Medicine, School of Medicine, University of California, San Diego, California.
authors.forename: Arturo
authors.initials: A
authors.lastname: Dominguez
authors.affiliation: Department of Family Medicine and Public Health, School of Medicine, University of California, San Diego, California; Department of Medicine, School of Medicine, University of California, San Diego, California; Veterans Affairs San Diego Healthcare System, San Diego, California.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Allison
authors.affiliation: Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Christina L
authors.initials: CL
authors.lastname: Wassel
authors.affiliation: Department of Family Medicine and Public Health, School of Medicine, University of California, San Diego, California; Department of Medicine, School of Medicine, University of California, San Diego, California; Veterans Affairs San Diego Healthcare System, San Diego, California.
authors.forename: Dena E
authors.initials: DE
authors.lastname: Rifkin
authors.affiliation: Department of Family Medicine and Public Health, School of Medicine, University of California, San Diego, California.
authors.forename: Cindy G
authors.initials: CG
authors.lastname: Morgan
authors.affiliation: Department of Family Medicine and Public Health, School of Medicine, University of California, San Diego, California.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Daniels
authors.affiliation: Department of Family Medicine and Public Health, School of Medicine, University of California, San Diego, California.
authors.forename: Umaira
authors.initials: U
authors.lastname: Ikram
authors.affiliation: Department of Family Medicine and Public Health, School of Medicine, University of California, San Diego, California.
authors.forename: Jessica B
authors.initials: JB
authors.lastname: Knox
authors.affiliation: Scripps Health, La Jolla, California.
authors.forename: C Michael
authors.initials: CM
authors.lastname: Wright
authors.affiliation: Department of Family Medicine and Public Health, School of Medicine, University of California, San Diego, California.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Criqui
authors.affiliation: Department of Family Medicine and Public Health, School of Medicine, University of California, San Diego, California; Department of Medicine, School of Medicine, University of California, San Diego, California; Veterans Affairs San Diego Healthcare System, San Diego, California. Electronic address: joix@ucsd.edu.
authors.forename: Joachim H
authors.initials: JH
authors.lastname: Ix
mesh_terms: D000368:Aged; D055424:Cardiac-Gated Imaging Techniques; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000401:mortality*; D003331:Coronary Vessels / Q000000981:diagnostic imaging*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011379:Prognosis; D013902:Radiography, Thoracic; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D061205:Vascular Calcification / Q000000981:diagnostic imaging* / Q000401:mortality*
keywords: chest computed tomography; coronary artery calcium; epidemiology; mortality