Relationship between Increased Urinary Albumin Excretion and Cardiovascular Mortality Risk in the General Population

Background: Albuminuria and reduced GFR are well-known risk factors for cardiovascular disease in diabetic patients, as well as in the general population. However, there are limited studies investigating the relationship between the increase in urinary albumin excretion and cardiovascular mortality in Asian population. The aim of this study was to examine if increased urinary albumin excretion is associated with cardiovascular mortality in the Japanese general population.
Methods: The study population consisted of 3093 inhabitants of Watari town, Miyagi prefecture, Japan, who participated in an annual health check-up in 2009. We measured anthropometric variables and sitting blood pressures. Fasting blood samples for lipids/glucose measurements, and morning spot urine samples for albumin-creatinine ratio (ACR) were obtained. We excluded subjects with overt albuminuria (ACR ≥300mg/gCr), or missing data at baseline. The subjects were divided into 3 groups according to the baseline ACR (<15, 15-29.9, and 30≤ mg/gCr), and followed prospectively for up to 7 years.
Results: We observed 123 deaths during a mean follow-up period of 69.7 months. Multivariate Cox proportional hazards analysis demonstrated that subjects with ACR of 15-29.9mg/gCr and ≥30mg/gCr had a significantly increased risks for cardiovascular mortality (hazards ratio, 3.314 and 7.328, respectively) compared with the lowest ACR (<15mg/gCr) group after adjustment for possible confounding factors including baseline eGFR levels.
Conclusion: An increased urinary albumin excretion, even within the normal range (<30mg/gCr), was associated with cardiovascular mortality in the Japanese general population.