[Clinical significance of proteinuria and renal function: findings from a population-based cohort, the Takahata study].

Proteinuria/albuminuria and renal insufficiency are major components of chronic kidney disease (CKD), and are strongly associated with end-stage renal disease, cardiovascular events and premature death. To clarify the prevalence of these renal disorders and the association between renal disorders and mortality in the Japanese population, we conducted a community-based longitudinal study. This study included 3,445 registered Japanese subjects, with a 7-year follow-up. Proteinuria/albuminuria was evaluated using dipstick strips and the urinary protein/albumin creatinine ratio (PCR/ACR). Glomerular filtration rate (GFR) was estimated using the equation for Japanese subjects. The prevalence of dipstick proteinuria, proteinuria (PCR > or = 0.15 g/gCr), albuminuria(ACR > or =30 mg/gCr) and renal insufficiency(estimated GFR< 60 ml/min/1.73m2) were 5%, 8%, 15% and 7%, respectively. The overlap between urinary abnormality and renal insufficiency was small. The prevalence of proteinuria/albuminuria increased along with the increase of blood pressure, 24-hour urinary sodium excretion, HbAlc and the number of components of metabolic syndrome. Kaplan Meier analysis showed that all-cause mortality was significantly increased along with the increase in urinary albumin excretion and the subjects with albuminuria showed a significantly higher mortality rate than those without albuminuria. Cox proportional hazard analysis after adjusting for possible confounders showed that albuminuria was an independent risk for all-cause and cardiovascular mortality. In conclusion, proteinuria/albuminuria and renal insufficiency are prevalent and were independently associated with mortality in the Japanese general population. The detection of renal disorders at the earliest opportunity is important to prevent premature death.