Albuminuria, metabolic syndrome and the risk of mortality and cardiovascular events

Abstract

Aim: Increased urinary albumin-excretion is a cardiovascular risk-factor. The cardiovascular risk of the metabolic syndrome (MetS) is debated. The aim of the present prospective, population-based study of non-diabetic individuals was to examine the association between low-grade urinary albumin-excretion, MetS, and cardiovascular morbidity and all-cause mortality.

Methods: 5215 non-diabetic, non-proteinuric men and women participating in the Tromsø Study 1994-1995 were included. Urinary albumin-creatinine ratio (ACR) was measured in three urine samples. The participants were categorized into four groups by the presence/absence of MetS (the International Diabetes Federation definition) and ACR in the upper tertile (>or=0.75 mg/mmol).

Results: Median follow-up time was 9.6 years for first ever myocardial infarction, 9.7 years for ischemic stroke and 12.4 years for mortality. High ACR (upper tertile)/MetS was associated with increased risk of myocardial infarction (hazard ratio (HR) 1.75; 95% confidence interval (CI): 1.30-2.37, p<0.001), stroke (HR 2.48; 95% CI: 1.66-3.71, p<0.001), and all-cause mortality (HR 1.63; 95% CI: 1.32-2.01, p<0.001) compared to reference (low ACR/no MetS). Similar associations were found for the high ACR/no MetS group. Low ACR/MetS was associated with myocardial infarction only (HR 1.82; 95% CI: 1.39-2.37, p<0.001). MetS predicted neither stroke nor mortality. Adjusted for its individual components, MetS was not associated with any end-point.

Conclusions: ACR>or=0.75 mg/mmol was associated with cardiovascular morbidity and all-cause mortality independently of MetS. MetS was not associated with any end-point beyond what was predicted from its components. Thus, low-grade albuminuria, but not MetS, may be used for risk stratification in non-diabetic subjects.