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Prognostic significance of night-time, early morning, and daytime blood pressures on the risk of cerebrovascular and cardiovascular mortality: the Ohasama Study

Metoki, Hirohitoa,b; Ohkubo, Takayoshib,c; Kikuya, Masahiroa; Asayama, Keic; Obara, Takua,b; Hara, Azusaa,b; Hirose, Takuoa,b; Hashimoto, Junichirob,c; Totsune, Kazuhitoa,b; Hoshi, Haruhisad; Satoh, Hiroshib,e; Imai, Yutakaa,b

doi: 10.1097/01.hjh.0000242409.65783.fb
Original papers: Stroke

Objective To clarify whether high blood pressure (BP) at a particular time of day is associated with cerebrovascular and cardiovascular mortality risk.

Methods Cerebrovascular and cardiovascular mortality in 1360 individuals aged 40 years and older in Ohasama, Japan, was followed for an average of 10.6 years. We used 2-h moving averages of the BP (a total of 24 average BP measurements for two consecutive hours based on four BP readings taken every 30 min) to compare the predictive power of BP taken during a 24-h period given the same number of measurements. The associations between cerebrovascular and cardiovascular mortality risk and the 2-h moving averages of systolic blood pressure (2 h-SBP) recorded over 24 h were analysed using a Cox proportional hazards model after adjusting for possible confounding factors.

Results The total cerebrovascular and cardiovascular mortality risk was significantly associated with elevated 2 h-SBP recorded during the night and early morning periods. Haemorrhagic stroke mortality was significantly associated with elevated daytime 2 h-SBP. Cerebral infarction mortality and heart disease mortality were significantly associated with elevated night-time 2 h-SBP.

Conclusion High BP at different times of day were associated with different subtypes of cerebrovascular and cardiovascular mortality risk.

aDepartments of Clinical Pharmacology and Therapeutics, Japan

bPlanning for Drug Development and Clinical Evaluation, Japan

cEnvironmental Health Sciences, Japan

dTohoku University 21st Century COE Program Comprehensive Research and Education Center for Planning of Drug Development and Clinical Evaluation, Tohoku University Graduate School of Pharmaceutical Sciences and Medicine, Sendai, Japan

eOhasama Hospital, Iwate, Japan

Received 24 February, 2006

Revised 6 April, 2006

Accepted 18 April, 2006

Correspondence to Takayoshi Ohkubo, MD, PhD, Department of Planning for Drug Development and Clinical Evaluation, Clinical Pharmacology and Therapeutics, Tohoku University Hospital, 1-1, Seiryo-cho, Aoba-ku, Sendai, Miyagi 980-8574, Japan Tel: +81 22 717 8590; fax: +81 22 717 8591; e-mail:

Sponsorship: This work was supported by grants for scientific research (nos. 14657600, 14370217, 15790293, and 1654041) from the Ministry of Education, Culture, Sports, Science, and Technology; and health science research grants and medical technology evaluation research grants from the Ministry of Health, Labor and Welfare, Japan; Japan Atherosclerosis Prevention Fund; Uehara Memorial Foundation; and Takeda Medical Research Foundation.

© 2006 Lippincott Williams & Wilkins, Inc.