Observed relationship between ratios HDL-cholesterol/total cholesterol and apolipoprotein A1/apolipoprotein B

Epidemiological evidence suggests that the ratio HDL-cholesterol (HDL-C)/total cholesterol (TC) or apolipoprotein A1 (apo A1)/apolipoprotein B (apo B) are good indicators of coronary heart disease risk. In investigating the distribution of these ratios in the typical population served by our routine laboratory, we analysed the lipid results of 541 serum samples submitted over a 2-month period for TC, HDL-C, apo A1, and apo B. Good correlation was observed between HDL-C and apo A1 (r = 0.664), and between TC and apo B (r = 0.674). Surprisingly, the correlation between the ratios HDL-C/TC (range: 0.05-0.40) and apo A1/apo B (range: 0.27-3.71) was even higher (r = 0.822). Similar significant correlations were observed in 31 heterozygous and 20 homozygous familial hypercholesterolemic subjects, viz. the correlations between HDL-C/TC (ranges: 0.04-0.24 and 0.02-0.12, respectively) and apo A1/apo B (ranges: 0.47-1.84 and 0.15-1.12, respectively) were r = 0.951 and r = 0.972, respectively.