Associations of proteinuria and the estimated glomerular filtration rate with incident hypertension in young to middle-aged Japanese males

Objective: To investigate the independent associations of proteinuria and the estimated glomerular filtration rate (eGFR) with incident hypertension. Methods: We investigated 29,181 Japanese males 18-59years old without hypertension in 2000 and examined whether proteinuria and the eGFR predicted incident hypertension independently over 10years. Incident hypertension was defined as a newly detected blood pressure of≥140/90mmHg and/or the initiation of antihypertensive drugs. Proteinuria and the eGFR were categorized as dipstick negative (reference), trace or≥1+ and≥60 (reference), 50-59.9 or <50ml/min/1.73m², respectively. Cox proportional hazards models were used to estimate the hazard ratios (HRs) of incident hypertension. Results: At baseline, 236 (0.8%) and 477 (1.6%) participants had trace and≥1+ dipstick proteinuria, while 1416 (4.9%) and 129 (0.4%) participants had an eGFR of 50-59.9 and <50ml/min/1.73m², respectively. The adjusted HRs were significant for proteinuria≥1+ (HRs 1.20, 95% CI: 1.06-1.35) and an eGFR of <50ml/min/1.73m² (1.29, 1.03-1.61). When two non-referent categories were combined (dipstick≥trace vs. negative and eGFR<60 vs.≥60ml/min/1.73m²), the association was more significant for proteinuria (1.15, 1.04-1.27) than for eGFR (0.99, 0.92-1.07). Conclusions: Proteinuria and a reduced eGFR are independently associated with future hypertension in young to middle-aged Japanese males.