3.4. Canonical Correlation Analysis between Blood Lipids and Inflammation
inflammation
CVD, INFLAMMATION, BLOOD
To determine whether inflammatory, antioxidant, and blood lipid markers were associated in participants with CVD during the clinical trial, canonical correlation analysis was used. Canonical correlation analysis is a multivariate analysis of associations between two sets of variables, where each set consists of multiple related outcomes. It determines linear combinations of variables (called canonical variates) from each set that maximize the correlations among all possible linear combinations.In the current study, inflammation was represented by a set of inflammatory and oxidation markers composed of hsCRP, IL-1, IL1Ra, IL-6, TNF-α, haptoglobin, TAS, and TBARS, all of which were log-transformed prior to analysis. Blood lipids were represented by LDL-C, HDL-C, and triglycerides. The loading coefficient of a canonical variate represents the contribution of each variable to the canonical variate. The 1st and 2nd canonical variates between blood lipids and the inflammation–oxidation markers are shown in The 1st canonical variate for lipids was highly correlated with LDL-C (r = 0.715); thus, this variate was most represented by LDL-C. The 2nd canonical variate is most represented by triglycerides (r = 0.971) and both variates were negatively correlated with HDL (r = −0.605 and −0.674, respectively). For inflammation, the 1st canonical variate was represented by hsCRP and IL-1Ra, and the 2nd variate is represented by IL-1, haptoglobin, and, to a lesser degree, IL-6, and TBARS. Helioplots showing correlations between canonical variates and their components are shown in The 1st correlation coefficient between the two sets of variables was r = 0.72 and the corresponding pair of canonical variates explained 62% of the variability between the biomarkers. The 2nd canonical correlation coefficient was r = 0.60 and the corresponding pair of canonical variates explained 32% of the variability. This implies that hsCRP and IL1-Ra appear to be positively associated with LDL-C and negatively with HDL-C and IL-6 and haptoglobin appears to be positively correlated with triglycerides and negatively with HDL-C.