Lipoprotein(a) and Cardiovascular Risk Prediction Among Women.

BACKGROUND: Although lipoprotein(a) [Lp(a)] is associated with incident cardiovascular disease (CVD), its contribution to prediction remains controversial.

OBJECTIVES: This study examined the association and clinical utility of Lp(a) with incident CVD in women.

METHODS: A turbidimetric assay assessed Lp(a) in 3 cohorts of women (the WHS [Women's Health Study] [N = 24,558], a case-cohort sample from the WHI [Women's Health Initiative] Observational Study [n = 1,815 cases, subcohort n = 1,989], and the JUPITER [Justification for Use of Statins in Prevention] trial [n = 2,569]) and in men from JUPITER (n = 5,161). A WHS derivation sample (n = 16,400) determined the form of association with incident CVD. This was tested in WHS validation data (n = 8,158) and the other study samples. Models including traditional CV risk factors but with and without Lp(a) were compared using risk reclassification.

RESULTS: In the WHS, there was a curvilinear association, with increased CVD risk among those with Lp(a) >50 mg/dl, but only among women with total cholesterol (TC) >220 mg/dl. In the WHS test sample, there was a small but significant change in the C-statistic (0.790 to 0.797; p = 0.035) but no improvement in measures of reclassification. This pattern was replicated among women in the WHI and JUPITER trial. In contrast, there was a strong association of Lp(a) with CVD among men with low TC levels in JUPITER.

CONCLUSIONS: In 3 cohorts of women, Lp(a) was associated with CVD only among those with high TC, and improvement in prediction was minimal. These data have implications for Lp(a) in clinical practice among women and for trials of Lp(a)-lowering agents.