C-Reactive Protein and Soluble Vascular Cell Adhesion Molecule-1 Are Associated With Elevated Urinary Albumin Excretion but Do Not Explain Its Link With Cardiovascular Risk

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Abstract
An elevated urinary albumin excretion rate (UAER) is associated with an increased risk of cardiovascular mortality, but the pathophysiological mechanism underlying this association is poorly understood. To investigate the role of endothelial dysfunction, leukocyte adhesion, and low-grade inflammation (1) in the development of elevated UAER (study I) and (2) in linking elevated UAER with risk of cardiovascular mortality (study II), we performed a prospective study in an age–, sex–, and glucose tolerance– stratified sample of a population-based cohort aged 50 to 75 years. High levels of von Willebrand factor, soluble vascular cell adhesion molecule-1 (sVCAM-1), and C-reactive protein (CRP) were used as markers of endothelial dysfunction, leukocyte adhesion, and low-grade inflammation, respectively. For study I, subjects who had normal UAER at baseline (n=316 subjects, 66 with type 2 diabetes) were reexamined after a mean follow-up of 6.1 years. The development of elevated UAER was defined as a mean albumin-to-creatinine ratio >2.0 mg/mmol at follow-up. Age–, sex–, and glucose tolerance– adjusted logistic regression analyses showed the development of elevated UAER to be significantly associated with levels of sVCAM-1 and CRP (odds ratio 1.14 [95% CI 1.02 to 1.27] per 10% increase of sVCAM-1 and odds ratio 1.17 [95% CI 1.04 to 1.32] per 50% increase of CRP). The results were not materially different after additional adjustment for hypertension, body mass index, cardiovascular disease, and creatinine clearance or stratification by the presence of diabetes. For study II, the vital status of all subjects (n= 575) was determined after a mean follow-up of 6.6 years. Eighty-one of 575 subjects died (30 died of cardiovascular disease). The presence of elevated UAER at baseline was associated with a 4.1-fold (1.94 to 8.73) increased risk of cardiovascular death after adjustment for age, sex, and glucose tolerance status. Adjustment for levels of von Willebrand factor, sVCAM-1, or CRP did not materially affect the results, nor did additional adjustment for the presence of hypertension, retinopathy, and cardiovascular disease and for levels of homocysteine, triglycerides, and high density lipoprotein cholesterol. Leukocyte adhesion (sVCAM-1) and low-grade inflammation (CRP) are determinants of the development of elevated UAER. However, these determinants do not explain the association between elevated UAER and cardiovascular mortality.