Hypertension. 2005;45:240.

Masahiro Kikuya; Takayoshi Ohkubo; Kei Asayama; Hirohito Metoki; Taku Obara; Shin Saito; Junichiro Hashimoto; Kazuhito Totsune; Haruhisa Hoshi; Hiroshi Satoh; Yutaka Imai From the Department of Planning for Drug Development and Clinical Evaluation (K.M.， T.O.， J.H.)， Tohoku University 21st Century COE Program Comprehensive Research and Education Center for Planning of Drug Development and Clinical Evaluation (T.O.， J.H.， K.T.， H.S.， Y.I.)， Clinical Pharmacology and Therapeutics (K.A.， H.M.， T.O.， S.S.， K.T.， Y.I.)， Environmental Health Science (H.S.)， Tohoku University Graduate School of Medicine and Pharmaceutical Science， Sendai， Japan; and Ohasama Hospital (H.H.)， Iwate， Japan.

The objective of this study was to elucidate the long-term prognostic significance of ambulatory blood pressure. Ambulatory and casual blood pressure values were obtained from 1332 subjects (872 women and 460 men) aged 40 years from the general population of a rural Japanese community. Survival was then followed for 14 370 patient years and analyzed by a Cox hazard model adjusted for possible confounding factors. There were 72 cardiovascular deaths during the 10.8-year follow-up. The relationship between 24-hour systolic blood pressure and the cardiovascular mortality risk was U-shaped in the first 5 years， then changed to J-shaped over the rest of the 10.8-year follow-up. After censoring the first 2 years of data， the risk flattened until it again increased for the fifth quintile of 24-hour systolic blood pressure for the 10.8-year follow-up period. For 24-hour diastolic blood pressure， the J-shaped relationship remained unchanged， regardless of follow-up duration and censoring. Ambulatory systolic blood pressure values consistently showed stronger predictive power for cardiovascular mortality risk than did casual systolic blood pressure in the 10.8-year follow-up data， whereas such relationships became more marked after censoring the first 2 years. When nighttime and daytime systolic blood pressure values were simultaneously included in the same Cox model， only nighttime blood pressure significantly predicted the cardiovascular mortality risk for the 10.8-year follow-up data. We conclude that the relationship between ambulatory systolic blood pressure and cardiovascular mortality is not U-shaped or J-shaped， and that nighttime blood pressure has better prognostic value than daytime blood pressure.