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Impact of obesity on incident hypertension independent of weight gain among nonhypertensive Japanese: the Ibaraki Prefectural Health Study (IPHS)

Tsujimoto, Takehikoa,b; Sairenchi, Toshimia,c; Iso, Hiroyasud; Irie, Fujikoe; Yamagishi, Kazumasaa,b; Tanaka, Kiyojib; Muto, Takashic; Ota, Hitoshia

doi: 10.1097/HJH.0b013e328352b879

Objective: The aim of this study was to examine the association between BMI and risk of incident hypertension among Japanese men and women who are middle-aged and older.

Design: Prospective, population-based cohort study.

Patients: A total of 68 205 nonhypertensive adults (18 336 men and 49 869 women) aged 40–79 years who completed health check-ups in the Ibaraki prefecture, Japan, in 1993 were followed up through 2006. To exclude the impact of BMI change during the follow-up period, a time-dependent covariate Cox proportional hazards model was used to compute the hazard ratios of incident hypertension according to BMI categories. Incident hypertension was defined as a SBP of at least 140 mmHg, a diastolic BP of at least 90 mmHg, and/or hypertensive medication use.

Results: A total of 30 982 adults (45.4%) developed hypertension (9331 men and 21 651 women) during a mean of 3.9 years of follow-up. Compared with a BMI of less than 19.0, time-dependent covariates adjusted hazard ratios [95% confidence interval (CI)] for hypertension among participants with a BMI of at least 25.0 were 1.42 (1.17–1.73) for men aged 40–59 years, 1.34 (1.19–1.51) for men aged 60–79 years, 1.47 (1.33–1.62) for women aged 40–59 years, and 1.29 (1.18–1.41) for women aged 60–79 years.

Conclusion: The baseline BMI is associated with future risk for incident hypertension even after accounting for weight change during the follow-up period. Weight loss may be recommended to nonhypertensive obese adults to prevent the development of hypertension.

aIbaraki Health Plaza, Ibaraki Health Service Association

bGraduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki

cDepartment of Public Health, Dokkyo Medical University School of Medicine, Tochigi

dDepartment of Social and Environmental Medicine, Graduate School of Medicine, Osaka University, Osaka

eDepartment of Health and Welfare, Ibaraki Prefectural Office, Ibaraki, Japan

Correspondence to Toshimi Sairenchi, PhD, Department of Public Health, Dokkyo Medical University School of Medicine, 880 Kita-kobayashi, Mibu, Tochigi 321-0293, Japan. Tel: +81 282 87 2133; fax: +81 282 86 2935; e-mail:

Abbreviations: BP, blood pressure; CI, confidence interval; HDL, high-density lipoprotein

Received 27 September, 2011

Revised 11 February, 2012

Accepted 17 February, 2012

© 2012 Lippincott Williams & Wilkins, Inc.