Relationship of advanced atherosclerosis lesions to fibrous plaques in 19 location-race groups

Aortas and coronary arteries from 23,000 autopsies of 19 location-race groups (L/R) were graded for % surface fatty streaks (FS), fibrous plaques (FP) and advanced lesions (AL = calcified, hemorrhagic, ulcerated, or thrombotic). Cases were classed by age (24-34, 35-44, 45-54, 55-64, and 65-69), sex, L/R, broad cause of death category (C/D; athero = related to atherosclerosis; basal = all other), and % surface raised lesions (RL = FP + AL). AL was converted to "advanced among lesions" (AaR = AL divided RL) because AaR was found on the average within each subgroup of subjects to hold a nearly constant ratio to RL (i.e. AaR : RL = K, an empirical constant). This ratio was different for each age (older greater than younger), C/D (athero greater than basal), and sex (M greater than F) subgroup and for coronary vs. aorta, thus requiring 5 X 2 X 2 X 2 = 40 values of K to describe the pools of subjects. The values of K were essentially same for all 19 location-race groups. If it be assumed that advanced lesions arise only be evolution from fibrous plaques, then the speed of this evolution up to each specified age is measured by K, in the sense that at a particular age larger K implies faster evolution. On the average, the rate of evolution in this sense was found to be the same in all location-race groups. Within groups a large variability of K among individuals was found, and this variation remains unexplained. However, across location-race boundaries no such variability was found, and this implies that the magnitude of K is not under control of geographically variable factors.