Lipoprotein(a) and its correlates in Japanese and U.S. population samples

To examine whether serum levels of lipoprotein(a) [Lp(a)], a potential coronary risk factor, are higher in Caucasian-Americans than in Japanese, a circumstance that would correspond to the higher mortality from coronary heart disease in the United States than in Japan, we analyzed serum Lp(a) levels in 300 nonsmoking men and women aged 47-69 years. Participants were drawn from two population-based samples: rural Japanese living in Akita and Caucasians living in Minneapolis-St. Paul, MN. Geometric mean and median serum Lp(a) concentrations were higher (P < 0.05) in Japanese than in Caucasians for both men (difference in geometric mean = 3.2 mg/dL) and women (difference = 5.3 mg/dL). There was however, no racial difference in the proportion of elevated Lp(a) concentrations (i.e., > or = 30 mg/dL) in either sex. Alcohol intake was inversely correlated with Lp(a) levels in Japanese men, who had a high average alcohol intake, but not in other sex and racial groups. Serum Lp(a) was nonsignificantly but consistently correlated with plasma fibrinogen and LDL-cholesterol for all sex and racial groups. With adjustment for alcohol intake, LDL-cholesterol, and plasma fibrinogen, the Japanese-Caucasian difference in geometric mean Lp(a) values was even larger for men and was not changed for women. Results of the present study do not support the hypothesis that racial differences in Lp(a) concentrations contribute to the higher mortality rate from coronary heart disease in the United States than in Japan.