Albuminuria is an independent predictor of all-cause and cardiovascular mortality in the Japanese population: the Takahata study

Abstract

Albuminuria is a known risk factor for cardiovascular events and premature deaths. However, the association between urinary albumin excretion and mortality is unknown in the Japanese population. To clarify this, we conducted a community-based longitudinal study. This study included 3,445 registered Japanese subjects (mean age 62.6years), with a 7-year follow-up. Albuminuria was defined as a urine albumin-creatinine ratio (ACR)≥30mg/g in the morning spot urine. Subjects with albuminuria (n=514, 14.9%) were older and showed a higher prevalence of hypertension, obesity, and diabetes and lower values of estimated glomerular filtration rate (eGFR) than those without albuminuria (n=2931, 85.1%). During the follow-up, 138 subjects died. A Kaplan-Meier analysis showed that all-cause mortality significantly increased along with the increase in urine albumin excretion (log-rank test, P<0.001). The subjects with albuminuria showed a significantly higher mortality rate than those without albuminuria (7.4 vs. 3.4%; log-rank test, P<0.001). A Cox proportional hazard model analysis after adjusting for possible confounders showed that albuminuria was an independent risk factor for all-cause and cardiovascular mortality (hazard ratio [HR] 1.69, 95% confidence interval [CI] 1.12-2.56 and HR 2.27, 95% CI 1.10-4.70, respectively) but not for noncardiovascular mortality. These associations were preserved after excluding subjects with high ACR (≥300mg/g). Albuminuria was a risk factor for all-cause and cardiovascular mortality in the Japanese population. To detect subjects with a high risk for premature death, measuring urinary albumin excretion might be useful.