Abstract 17863: Is Isolated Nocturnal Hypertension a Reproducible Ambulatory Blood Pressure Phenotype?
Background: Isolated nocturnal hypertension (INH), defined as nocturnal without daytime hypertension, assessed using ambulatory blood pressure (ABP) monitoring (ABPM), is associated with increased risk of cardiovascular (CVD) events and mortality, compared to day and night normotension (DNN). The study aim was to determine the reproducibility of INH.
Methods: The Improving the Detection of Hypertension Study is a community-based study of adults in upper Manhattan without CVD, renal failure, or treated hypertension (HT). Clinic BP (CBP) and 24-hr ABP were assessed in 283 participants (42% male, mean ± SD age and body mass index were 39.4 ± 12.9 years and 27.0 ± 4.9 kg/m2 respectively). Manual CBP measurements (n=3) were obtained, and ABPM measurements were taken at 30-min intervals. 24-hour ABPM was performed twice over a 3-week period using a Spacelabs 90207 monitor (Snoqualmie, WA). Daytime HT was defined as mean awake ≥ 135/85 mmHg and nocturnal HT as mean sleep ≥ 120/70 mmHg. INH was as defined as nocturnal without daytime HT, isolated daytime HT (IDH) as daytime without nocturnal HT, day and night HT (DNH) as daytime and nocturnal HT, and DNN as absence of daytime and nocturnal HT.
Results: Mean ± SD systolic/diastolic CBP, awake systolic/diastolic ABP, and sleep systolic/diastolic ABP were 116 ± 16 /76 ± 10 mmHg, 125 ± 12 /78 ± 8 mmHg, and 109 ± 12 /64 ± 9 mmHg respectively. The Table shows the cross-classification of ABP HT categories across the two ABPM recordings. The kappa statistics for daytime HT, nocturnal HT, INH, IDH, and DNH were 0.66 (95% CI 0.55-0.76), 0.65 (95% CI 0.55-0.75), 0.20 (95% CI -0.04-0.44), 0.24 (-0.02-0.50), and 0.65 (95% CI 0.53-0.77) respectively.
Conclusions: Daytime HT, nocturnal HT, and DNH were reproducible phenotypes. In contrast, INH and IDH were poorly reproducible. These findings suggest that INH may not be a stable phenomenon, which has important implications for the risk stratification of individuals using ABPM.
Author Disclosures: M. Abdalla: None. J. Goldsmith: None. K.M. Diaz: None. P. Muntner: Research Grant; Significant; Amgen, Inc. Consultant/Advisory Board; Modest; Amgen, Inc. J.E. Schwartz: None. D. Shimbo: None.
- © 2014 by American Heart Association, Inc.