Slight increase in urinary albumin excretion within the normal range predicts incident hypertension in a community-based Japanese population: The Takahata study

Recent studies have suggested that urine albumin excretion in the high normal range predicts hypertension. However, the relationship between urinary albumin excretion in spot urine and incident hypertension remains unclear in the general Japanese population. To clarify this relationship, we conducted a cohort study in a community-based population of 412 normotensive individuals without diabetes and renal insufficiency and examined the incidence of hypertension using the urinary albumin-to-creatinine ratio (UACR) at baseline. Incident hypertension was defined as new-onset systolic blood pressure ≥140 mm Hg and/or diastolic blood pressure ≥90 mm Hg and/or the use of anti-hypertensive drugs. During the follow-up period (median, 6.7 years), 133 subjects (32.3%) newly developed hypertension. The incidence of hypertension increased with an increase in baseline UACR (20.4% for UACR <5 mg g -1, 34.0% for 5-9.9 mg g -1 UACR and 40.4% for 10-29.9 mg g -1, P=0.002). Multivariate logistic regression analysis, after adjustment for possible confounders, showed that UACR 5-9.9 mg g -1 and 10-29.9 mg g -1 were independent risks for incident hypertension compared with UACR <5 mg g -1 (odds ratio (OR) 2.15, 95% confidence interval (CI) 1.16-4.10 and OR 2.67, 95% CI 1.36-5.38, respectively). Subgroup analysis revealed that subjects with increased UACR (≥5 mg g -1) had a higher risk of incident hypertension than did those with low UACR (<5 mg g -1), irrespective of their backgrounds (age, sex, smoking, alcohol consumption, obesity and urinary sodium excretion). In conclusion, this study showed that a slight increase in urinary albumin excretion might predict incident hypertension in a community-based Japanese population.