Abstract 3210: Lp(a) is Strongly Associated with Coronary Artery Calcification in Type 2 Diabetic Women
Introduction Lipoprotein (a) [Lp(a)] is a controversial risk factor for coronary heart disease (CHD) implicated in both atherogenesis and inhibition of fibrinolytic pathways. Previous studies show Lp(a) levels vary significantly by race, gender and presence of diabetes, making it difficult to determine in which populations Lp(a) measurement has use for CHD risk prediction.
Hypothesis We hypothesized that Lp(a) would be associated with coronary artery calcium (CAC), a measure of subclinical atherosclerosis, in type 2 diabetes to a greater extent than in non-diabetics, and that this relationship would be modified in race and gender subgroups with higher Lp(a) values.
Methods We performed cross-sectional analyses in two community based studies (19.7% Black): the Penn Diabetes Heart Study [(PDHS) N=1299 type 2 diabetics, 63% men] and the Study of Inherited Risk of Coronary Atherosclerosis [(SIRCA) N= 896 non diabetics, 53% men)] using multivariate analysis of Lp(a) association with CAC stratified by gender, race, and diabetes status.
Results Blacks had 2–3 fold higher Lp(a) levels than whites in both diabetic and non diabetic cohorts. Diabetic women had higher mean Lp(a) levels than diabetic men (48.2 vs. 31.9 mg/dl, p<0.001). There was significant interaction by gender (p<0.001) but not race in the association of Lp(a) with CAC in type 2 diabetics. In age and race adjusted models, Lp(a) in diabetic women was associated with CAC [tobit regression ratio 2.76 (95% CI 1.73– 4.40), p<0.001] with roughly similar effects in black women [3.67 (1.45–9.32), p=0.006] and white women [2.25 (1.31–3.87), p=0.003], and a race interaction p=0.5. This relationship in women was not attenuated in models further adjusted for exercise, medications, Framingham Risk Score, metabolic syndrome, BMI, CRP and hemoglobin A1c [2.25, (1.34 –3.79), p=0.002]. In contrast, Lp(a) was not associated with CAC in diabetic men, nor in non-diabetic men and women.
Conclusions Lp(a) is a strong independent predictor of CAC in type 2 diabetic women, regardless of race, but not in men. It does not relate to CAC in men or women without type 2 diabetes. Further investigation is needed to examine gender differences in the relationship to clinical CHD in diabetes and to explore potential mechanisms.