Objective: In Western populations, blood pressure (BP) measured at baseline has been reported to predict long-term (over 20 years) risk of mortality from cardiovascular diseases (CVDs). However, corresponding evidence is scarce in Asia where stroke is dominant. We investigated the association between baseline BP and 24-year mortality risk due to CVD, in a representative Japanese general population.
Methods: We followed up a nationwide sample of 8592 Japanese, aged 30 years or above without a history of CVD and antihypertensive medication at baseline, for 24 years. Hazard ratios for CVD mortality in BP categories defined according to JCN7 criteria were estimated using Cox model adjusted for potential confounding factors with normal BP treated as the reference category.
Results: We observed 689 CVD deaths. Hazard ratios for CVD mortality were progressively and significantly increased from the category of prehypertension. Population-attributable fraction (PAF) demonstrated that 43 and 48% of CVD and stroke deaths were explained by non-normal BP at baseline. Hazard ratios and PAF were remarkably higher in younger participants (aged 30–59 years) than those in the elderly (aged 60 years or above). Particularly, in younger men, 81% of CVD deaths were explained by non-normal BP. In sensitivity analysis, participants with antihypertensive medication showed the highest hazard ratio for CVD morality compared with the other categories.
Conclusions: BP levels above normal at baseline retained significant relative and absolute risks of CVD and stroke mortality during 24 years. Long-lasting burden of non-normal BP particularly in younger individuals suggests the importance of primary prevention of high BP from younger generation.
aDepartment of Health Science
bLifestyle-Related Disease Prevention Center, Shiga University of Medical Science, Shiga
cDepartment of Preventive Medicine and Public Health, School of Medicine, Keio University, Tokyo
dDepartment of Medical Statistics, Shiga University of Medical Science, Shiga
eDepartment of Epidemiology and Public Health, Kanazawa Medical University, Ishikawa
fDepartment of Hygiene and Preventive Medicine, Fukushima Medical University, Fukushima
gThe First Institute for Health Promotion and Healthcare, Japanese Anti-Tuberculosis Association, Tokyo, Japan
Correspondence to Naoyuki Takashima, MD, PhD, Department of Health Science, Shiga University of Medical Science, Seta Tsukinowa-cho, Otsu, Shiga 520-2192, Japan. Tel: +81 77 548 2191; fax: +81 77 543 9732; e-mail: email@example.com
Abbreviations: BP, blood pressure; CHD, coronary heart disease; CI, confidence interval; CVD, cardiovascular disease; ICD-10, 10th International Classification of Disease; ICD-9, 9th International Classification of Disease; PAF, population-attributable fraction
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Received 4 January, 2012
Revised 6 August, 2012
Accepted 23 August, 2012