Factor analysis of risk variables associated with iron status in patients with coronary artery disease.

OBJECTIVES: Epidemiological evidence concerning the role of iron, a lipid peroxidation catalyst, in atherosclerosis and coronary artery disease (CAD) is inconsistent.

DESIGN AND METHODS: Exploratory factor analysis was used to examine the potential clustering of variables known to be associated with CAD using data from 188 patients with angiographically-approved disease. The resulting factors were then tested for their association with serum ferritin and soluble transferrin receptor (sTfR) as indicators of body iron status.

RESULTS: Factor analysis resulted in a reduction of a variable number from the original 15 to 5 composite clusters. These factors were interpreted as (1) "proatherogenic factor" with positive loadings of TC, LDL-C, apoB and TG; (2) "inflammatory factor" with positive loadings of hsCRP, fibrinogen and MDA; (3) "antiatherogenic factor" with positive loadings of HDL-C and apoA-I; (4) "obesity factor" with positive loadings of weight and waist; and (5) "antioxidative status factor" with positive loadings of SOD and age and negative loading of superoxide anion. "Inflammatory", "obesity" and "antiatherogenic" factors predicted high ferritin values and the "proatherogenic factor" predicted high sTfR values. We compared the ability of the "proatherogenic factor" with that of a multivariable logistic model that included the "proatherogenic factor" and sTfR values in predicting significant stenosis in patients. The area under the ROC curve was 0.692 vs. 0.821, respectively.

CONCLUSIONS: "Inflammatory", "obesity", "antiatherogenic" and "proatherogenic" factors were associated with increased parameters of body iron status. The measurement of sTfR improves the prediction of CAD based on clustered cardiovascular risk factors.