Blood Pressure and the Risk of Stroke, Cardiovascular Disease, and All-cause Mortality Among Japanese: the JPHC Study

Background: Little is known about the influence of blood pressure (BP) on cardiovascular disease (CVD) outcomes among Asian populations.

Methods: We examined population attributable fractions (PAFs) and hazard ratios (HRs) associated with BP in relation to stroke and coronary heart disease (CHD) incident and mortality within a cohort of 33,372 Japanese men and women aged 40-69 years, free of prior diagnosis of cancer and CVD. The BP was classified based on modified criteria of the 2003 European Society of Hypertension-European Society of Cardiology guidelines. A total of 943 stroke events, 182 CHD events, 262 stroke deaths, and 120 CHD deaths occurred between the baseline questionnaire (1990-1994) and the end of follow-up in 31 December 2003.

Results: BP levels were linearly associated with incidence and mortality of CVD in men and women. According to the PAF estimation, the elimination of normal to severe hypertension would prevent 64% of stroke incidence in men and 50% in women; 67% of stroke mortality in men and 29% in women; and 38% of total CVD mortality in men and 36% in women. The PAF estimate for total stroke incidence was the highest for mild hypertension, and lower for moderate to severe hypertension in both sexes.

Conclusions: The contributions of normal BP, high normal BP, and mild hypertension to the occurrence of stroke events were greater than those made by moderate and severe hypertension, highlighting the importance of primary prevention and of treatment for low-to-moderate degrees of hypertension.