Is Isolated Nocturnal Hypertension a Novel Clinical Entity? Findings From a Chinese Population Study.

Hypertension. 2007 Jun 18;
Li Y, Staessen JA, Lu L, Li LH, Wang GL, Wang JG.
Centre for Epidemiological Studies and Clinical Trials, Ruijin Hospital, Shanghai Jiaotong University Medical School, Shanghai, China; and the Studies Coordinating Centre, Division of Hypertension and Cardiovascular Rehabilitation, Department of Cardiovascular Diseases, University of Leuven, Leuven, Belgium.

We reported previously that normotensive Chinese had higher nighttime diastolic blood pressure compared with non-Chinese. We, therefore, studied the prevalence and characteristics of isolated nocturnal hypertension (HT) and its association with arterial stiffness, an intermediate sign of target organ damage.

We recorded ambulatory blood pressure, the central and peripheral systolic augmentation indexes, the ambulatory arterial stiffness index, and brachial-ankle pulse wave velocity in 677 Chinese enrolled in the JingNing population study (53.6% women; mean age: 47.6 years). Prevalence was 10.9% for isolated nocturnal HT (>/=120/70 mm Hg from 10:00 PM to 4:00 AM), 4.9% for isolated daytime HT (>/=135/85 mm Hg from 8:00 AM to 6:00 PM), and 38.4% for day-night HT. Patients with isolated nocturnal HT, compared with subjects with ambulatory normotension (45.8%), were older (53.7 versus 40.7 years), more often reported alcohol intake (68.9% versus 51.0%), had faster nighttime pulse rate (62.8 versus 60.7 bpm), had higher serum cholesterol (5.12 versus 4.77 mmol/L), and had higher blood glucose (4.84 versus 4.38 mmol/L).

Similar to patients with isolated daytime HT or day-night HT, patients with isolated nocturnal HT had higher indexes of arterial stiffness (P<0.05) than subjects with ambulatory normotension (central augmentation index: 140% versus 134%; peripheral augmentation index: 82.6% versus 76.5%; ambulatory arterial stiffness index: 0.40 versus 0.35 U; brachial-ankle pulse wave velocity: 16.2 versus 14.7 m/s). Of 74 patients with isolated nocturnal HT, only 4 (5.4%) had hypertension on conventional office blood pressure measurement (>/=140/90 mm Hg).

In conclusion, isolated nocturnal HT can only be diagnosed by ambulatory blood pressure monitoring, is prevalent among Chinese, and is associated with increased arterial stiffness.




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