Racial and Ethnic Variation in Lipoprotein (a) Levels among Asian Indian and Chinese Patients

Background. Lipoprotein (a) [Lp(a)] is an independent risk factor for cardiovascular disease (CVD) in Non-Hispanic Whites (NHW). There are known racial/ethnic differences in Lp(a) levels, and the association of Lp(a) with CVD outcomes has not been examined in Asian Americans in the USA. Objective. We hypothesized that Lp(a) levels would differ in Asian Indians and Chinese Americans when compared to NHW and that the relationship between Lp(a) and CVD outcomes would be different in these Asian racial/ethnic subgroups when compared to NHW. Methods. We studied the outpatient electronic health records of 2022 NHW, 295 Asian Indians, and 151 Chinese adults age ≥18 y in Northern California in whom Lp(a) levels were assessed during routine clinical care from 2001 to 2008, excluding those who had received prescriptions for niacin (14.6%). Nonparametric methods were used to compare median Lp(a) levels. Significance was assessed at the P < .0001 level to account for multiple comparisons. CVD outcomes were defined as ischemic heart disease (IHD) (265 events), stroke (122), or peripheral vascular disease (PVD) (87). We used logistic regression to determine the relationship between Lp(a) and CVD outcomes. Results. Both Asian Indians (36 nmol/L) and NHW (29 nmol/L) had higher median Lp(a) levels than Chinese (22 nmol/L, P ≤ .0001 and P = .0032). When stratified by sex, the differences in median Lp(a) between these groups persisted in the 1761 men (AI v CH: P = .001, NHW v CH: P = .0018) but were not statistically significant in the 1130 women (AI v CH: P = .0402, NHW v CH: P = .0761). Asian Indians (OR = 2.0) and Chinese (OR = 4.8) exhibited a trend towards greater risk of IHD with high Lp(a) levels than NHW (OR = 1.4), but no relationship was statistically significant. Conclusion. Asian Indian and NHW men have higher Lp(a) values than Chinese men, with a trend toward, similar associations in women. High Lp(a) may be more strongly associated with IHD in Asian Indians and Chinese, although we did not have a sufficient number of outcomes to confirm this. Further studies should strive to elucidate the relationship between Lp(a) levels, CVD, and race/ethnicity among Asian subgroups in the USA.