Lipoprotein(a)-cholesterol and coronary heart disease in the Framingham Heart Study

Background: Increased plasma lipoprotein(a) [Lp(a)] concentrations have bee n reported to be an independent risk factor for coronary heart disease (CHD ) in some prospective studies, but not in others. These inconsistencies may relate to a lack of standardization and the failure of some immunoassays t o measure all apolipoprotein(a) isoforms equally. Methods: We measured plasma Lp(a)-cholesterol [Lp(a)C] in a Caucasian popul ation of offspring and spouses of the Framingham Heart Study participants, using a lectin-based assay (Lipopro(TM)). We compared the prevalence of inc reased Lp(a)-C to the presence of sinking pre-beta-lipoprotein (SPB). We al so related Lp(a)-C concentrations to the prevalence of CHD risk in the enti re population. Results: The mean (+/- SD) Lp(a)-C concentration in the Framingham populati on (n = 3121) was 0.186 +/- 0.160 mmol/L, with no significant gender or age differences. The mean Lp(a)-C concentrations in the absence or presence of SPB were 0.158 +/- 0.132 mmol/L and 0.453 +/- 0.220 mmol/L, respectively ( P <0.0001). The mean Lp(a)C concentration in men with CHD (n = 156) was 0.2 41 +/- 0.204 mmol/L, which was significantly (P <0.001) higher, by 34%, tha n in controls. The odds ratio for CHD risk in men with Lp(a)-C greater than or equal to 0.259 mmol/L (greater than or equal to 10 mg/dL), after adjust ing for age, HDL-cholesterol, LDL-cholesterol, smoking, diabetes, blood pre ssure, and body mass index, was 2.293 (confidence interval, 1.55-3.94; P <0 .0005). Lp(a)-C values correlated highly with a Lp(a)mass immunoassay [Apot ek(TM) Lp(a); r = 0.832; P <0.0001; n = 1000]. Conclusions: An increased Lp(a)-C value greater than or equal to 0.259 mmol /L (greater than or equal to 10 mg/dL) is an independent CHD risk factor in men with a relative risk of more than 2, but was inconclusive in women. Lp (a)-C measurements offer an alternative to Lp(a)-mass immunoassays and can be performed on automated analyzers. (C) 1999 American Association for Clin ical Chemistry.