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Characteristics of blood pressure measured at home in the morning and in the evening: the Ohasama study

Imai, Yutaka1,5; Nishiyama, Akimitsu1; Sekino, Makoto1; Aihara, Akiko1; Kikuya, Masahiro1; Ohkubo, Takayoshi2; Matsubara, Mistunobu1; Hozawa, Atsushi1,2; Tsuji, Ichiro2; Ito, Sadayoshi1; Satoh, Hiroshi3; Nagai, Kenichi4; Hisamichi, Shigeru2

Original article

Objective To determine the qualitative and quantitative differences of blood pressure measured at home (home measurement) in the morning versus the evening.

Methods Of 3744 participants, aged 20 years or older in the Ohasama population, more than 14 home measurements in the morning and in the evening, respectively, were obtained in each of 1207 individuals (881 untreated, 56.1 ± 11.4 years and 326 treated, 66.0 ± 9.2 years). A casual/screening measurement was also obtained in these individuals.

Results The home measurements in the morning were significantly higher than those in the evening. The bivariate linear regression analysis demonstrated that the difference between diastolic home measurement in the morning and that in the evening increased with an increase in diastolic home measurements. The multiple step-wise linear regression analysis, however, demonstrated that male sex, the use of antihypertensive medication, and SD of home measurements in individuals (blood pressure variability), but not level of home measurements, were positively associated with the difference between home measurement in the morning and that in the evening. The SD of home measurement in the evening in individuals was significantly larger than that in the morning, and the SD in treated individuals was significantly larger than that in untreated individuals. The correlations between casual and home measurements were moderate in untreated individuals (r = 0.509–0.567) but poor in treated subjects (r = 0.223–0.384). The correlations between home systolic measurements in the morning and in the evening were very close in both treated and untreated subjects (r = 0.814–0.902). The correlations between the SD of home measurements in the morning and in the evening were moderate in both treated and untreated individuals (r = 0.585–0.657).

Conclusions Qualitative and quantitative differences in home blood pressure measurement, due to the differential time of measurement, should be taken into consideration in clinical use of home blood pressure measurements.

1Department of Medicine, Tohoku University School of Medicine, Sendai, Japan

2Department of Public Health, Tohoku University School of Medicine, Sendai, Japan

3Department of Environmental Health Science, Tohoku University School of Medicine, Sendai, Japan

4Ohasama Hospital, Iwate, Japan.

5Correspondence and requests for reprints to: Yutaka Imai, Second Department of Medicine, Tohoku University School of Medicine, Sendai 980–8574, Japan.

Tel: +81 22 717 7167; fax: +81 22 717 7168; e-mail: imai@tinet-i.ne.jp

Sponsorship: This work was supported by research grants from the Miyagi Prefectural Kidney Association, by Research Grants from Takeda Medical Foundation (1997), and Mitsui Life Social Welfare Foundation (1998), by Research Grants entitled ‘Evaluation of the effect of drug treatment on hypertension and other chronic disease conditions in the elderly’, Kenko-Kagaku Chosa Kenkyuhi (1996 and 1997), Health Science Research Grant on Health Services, and Rojin Hoken Jigyo (1998) from the Ministry of Health and Welfare, and by a Research Grants for Scientific Research (10470102) and Research Grant for JSPS Research Fellow (T.D.) from the Ministry of Education, Science and Culture of Japan.

Received 9 Novermber 1998 Revised 10 March 1999 Accepted 22 March 1999

© 1999 Lippincott Williams & Wilkins, Inc.