Moderately Increased Albuminuria Is an Independent Risk Factor of Cardiovascular Events in the General Japanese Population under 75 Years of Age: The Watari Study

Background Moderately increased albuminuria (formerly called microalbuminuria) is widely recognized as a predictor of cardiovascular disease. However, it is not clear whether this observation is applicable to the Asian population, as studies leading to this conclusion were conducted on Western populations. The aim of this study was to examine the hypothesis if moderately increased albuminuria could be an independent predictor of cardiovascular mortality and morbidity in the Japanese population. Methods and Results The study population consisted of 3093 inhabitants of Watari, Miyagi Prefecture, who participated in an annual health check-up in 2009. We examined anthropometry, sitting blood pressure, fasting blood sample, and urine albumin-to-creatinine ratio (UACR). After baseline assessment, subjects were followed prospectively for up to 60 months. The incidence of major cardiovascular events (stroke, myocardial infarction, revascularization, and cardiovascular death) was determined based on death certificate records or medical claims sent to the National Health Insurance of Japan. Follow-up was discontinued for those who reached 75 years of age because they were moved to a different medical insurance system. We observed 57 cardiovascular events during a mean follow-up period of 47.8 months. The cumulative incidence rate for major cardiovascular events was significantly higher in patients with moderately increased albuminuria (UACR 30-299 mg/gCr) than in those with normoalbuminuria (UACR < 30 mg/gCr) (6.4% vs. 2.2%, p = 0.0002 by log-rank test). Multivariate Cox proportional hazards analyses have revealed that moderately increased albuminuria is an independent predictor of cardiovascular events (HR 2.386, 95% CI: 1.120-4.390). Conclusions Moderately increased albuminuria is an independent predictor of cardiovascular events in the general Japanese population under 75 years of age.