CAC Assessment

At the MESA baseline exam, CAC was measured by electron‐beam computed tomography at 3 field centers and by multidetector computed tomography at the other 3 field centers,28, 29 and these scans were read independently at a centralized reading center. The methodology for acquisition and interpretation of the scans has been documented previously.30 Amount of CAC was quantified using the Agatston scoring method.31, 32 Interobserver agreement and intraobserver agreement were found to be very high (κ=0.93 and 0.90, respectively). Validation of phantom‐adjusted CAC measurement was made to adjust for attenuation differences.31, 32 At Exam 5, participants of the MESA Air ancillary study underwent repeat CT scanning, allowing for a 10‐year assessment of incident CAC and change in CAC.

At each visit (MESA baseline and Exam 5), each participant was scanned twice consecutively, and the average CAC from the 2 scans from that respective visit was used in the analysis.