Agreement Between Ambulatory and Home Blood Pressure Monitoring in Detecting Nighttime Hypertension and Nondipping Patterns in the General Population

Abstract

Background: Nighttime blood pressure (BP) and nondipping pattern are strongly associated with hypertensive end-organ damage. However, no previous studies have compared the diagnostic agreement between ambulatory and home monitoring in detecting these BP patterns in the general population.

Methods: We studied a population-based sample of 180 persons aged 32-80 years. The study protocol included 24-hour ambulatory BP monitoring, home daytime measurements over 7 days, home nighttime measurements (6 measurements over 2 consecutive nights using a timer-equipped home device), and ultrasound measurements for left ventricular mass index (LVMI) and carotid intima-media thickness (IMT). We defined nondipping as a <10% reduction in nighttime BP compared with daytime BP, and nighttime hypertension as BP ≥ 120/70 mm Hg.

Results: The agreement between ambulatory and home monitoring for detecting nighttime hypertension was good (80%, κ = 0.56, P < 0.001). However, their agreement in detecting nondipping status was poor (54%, κ = 0.12, P = 0.09). The magnitude of ambulatory systolic BP dipping percent was 1.7% higher than on home monitoring (P = 0.004), whereas no difference was observed for diastolic BP dipping (difference: 0.7%, P = 0.33). LVMI and IMT were significantly greater among individuals with nighttime hypertension than in normotensive individuals, irrespective of the measurement method. However, only ambulatory nondippers, but not home nondippers, had more advanced end-organ damage than dippers.

Conclusion: We observed a good agreement between ambulatory and home BP monitoring in detecting nighttime hypertension in the general population. Two-night home monitoring could offer an inexpensive and feasible method for the diagnosis of nighttime hypertension.

Keywords: ambulatory blood pressure; blood pressure; carotid intima-media thickness; diagnosis; home blood pressure; hypertension; hypertensive end-organ damage; left ventricular hypertrophy; nighttime hypertension; nondipping.