Association Between Nocturnal Blood Pressure Dipping and Chronic Kidney Disease Among Patients With Controlled Office Blood Pressure

Abstract

BACKGROUND Although abnormal blood pressure (BP) patterns are associated with adverse cardiorenal outcomes, their associations are yet unquantified by nocturnal dipping status. We examined the association of nocturnal BP dipping pattern with albuminuria and kidney function among participants with controlled hypertension without prior advanced kidney disease. METHODS Ambulatory BP (ABP) measurements were collected from 995 middle-aged, cardiology clinic patients with controlled office BP (OBP) (<140/90 mm Hg). The magnitude of dipping was calculated as the difference between daytime and nighttime systolic BP (SBP) divided by daytime SBP. Accordingly, the participants were categorized as extreme-dipper (>= 20%), dipper (10% to <20%), non-dipper (0% to <10%), or reverse-dipper (<0%). We analyzed the cross-sectional associations of dipping with albuminuria (urine albumin-to-creatinine ratio >= 30 mg/g) and decreased estimated glomerular filtration rate (<60 ml/min/1.73 m(2)), adjusting for OBP/ABP, antihypertensive class, body mass index, total cholesterol, fasting glucose, socioeconomic status, and health behavior. RESULTS The participants (mean age 60.2 years; 52.9% male) consisted of 13.5% extreme-dippers, 43.1% dippers, 34.7% non-dippers, and 8.7% reverse-dippers. In reference to dippers, odds ratios [95% confidence interval] for albuminuria were 1.73 [1.04-2.60] in reverse-dippers, 1.67 [1.20-2.32] in non-dippers, and 0.62 [0.38-1.04] in extreme-dippers. Likewise, abnormal dipping profile was associated with decreased kidney function: reverse-dipping, 2.02 [1.06-3.84]; non-dipping, 1.98 [1.07-3.08]; extreme-dipping, 0.69 [0.20-1.17]. The associations persisted among participants with more conservatively controlled OBP (<130/80 mm Hg). CONCLUSIONS Monitoring diurnal and nocturnal BP may identify chronic kidney disease otherwise overlooked based on OBP.