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

AimIncreased 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.Methods5215 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 (≥0.75 mg/mmol).ResultsMedian 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.ConclusionsACR ≥ 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.