Histometric components of aortic atherosclerosis which vary or remain constant among eight populations.

In the objective examination of aortic histology, each position observed in a sample can be classed as having or not having atheronecrosis, and each aorta can be scored as affected in a measured percentage of the sample. Positions not having necrosis can be measured for intimal thickness and the mean of those measurements is an estimate of the quantity of intimal fibroplasia. Both atheronecrosis and fibroplasia, measured in these ways, increase with age. Within age groups these two variables are correlated with each other. By multivariate statistical methods, independent variation of the two variables among populations was assessed. Populations compared were from Bogota, Durban (Bantu and Indian), Manila, Mexico, New Orleans (Negro and White) and Sao Paulo. Manila ranked highest on the quantity of fibroplasia and Durban Bantu lowest. Sao Paulo ranked highest on the extent of atheronecrosis and New Orleans Negro was lowest. The two variables assorted among the eight populations independently of each other to a large degree, suggesting that fibroplasia and atheronecrosis are at least in part subject to separate and independent causes. The numbers of smooth muscle cells and the extent of foam cell infiltration did not differ significantly between atherosclerosis related and basal cause of death groups. These cellularity measures were, with minor exceptions, not significantly different among populations, suggesting that they are inherent human characteristics largely unaffected by environmental circumstances.