Student's t test and Wilcoxon rank sum test were employed to compare group means62–63. Pearson correlation, Spearman rank correlation and Somers' Dxy correlation were used to investigate the correlation between two variables64–65. Comparison of categorical measures between independent groups was done using χ2 tests66. Odds ratios and 95% confidence intervals (CI) for cardiovascular phenotypes (history of MI, CAD, PAD, CVD and CAD+PAD) were calculated with R, Version 2.10.1 (www.r-project.org), using logistic regression67 with case status as the dependent variable and plasma analyte as independent variable. Trend tests in frequencies across quartiles were done using Cochran-Armitage Trend tests68. Levels of analytes were adjusted for traditional CAD risk factors in a multivariate logistic regression model including individual traditional cardiac risk factors (age, gender, diabetes, smoking, hypertension, lipids, CRP and estimated creatinine clearance) and medication usage (statin or other lipid lowering agents, antihypertensive agents including angiotensin-converting enzyme inhibitor, angiotensin receptor blocking agent, diuretic, calcium channel blocker or beta blocker, and aspirin or other platelet inhibitors).