Understanding the decline of mean systolic blood pressure in Japan: an analysis of pooled data from the National Nutrition Survey, 1986-2002

Abstract

According to new research, declining mean systolic blood pressure (SBP) in Japan between 1986 and 2002 could be attributed to the increased use of antihypertensive medications, particularly among older adults, and lowered mean body mass index (BMI) in young women. The study, Understanding the decline of mean systolic blood pressure in Japan: an analysis of pooled data from the National Nutrition Survey, 1986-2002, is the first study to attempt to measure the contributions of relevant factors to the decline of mean SBP in Japan. The work was done in collaboration with scientists at the Nippon Medical School in Tokyo.

Research findings

The study identified two major contributors to the change of mean SBP in Japan from 1986 to 2002. First, the effect of antihypertensive medications was substantial in older adults. Second, the contribution of decreased mean BMI was substantial in women in their 30s and 40s, whereas increased mean BMI offset a large part of the decrease of mean SBP in men and elderly women. Lifestyle factors such as physical activity, alcohol drinking, and dietary salt intake made only limited contributions to the decline of mean SBP. The results of this study confirmed for the first time in the Japanese context the adverse effect of overweight and obesity on mean SBP.

Analytical approach

Researchers pooled data from the National Nutrition Survey, a nationally representative cross-sectional survey in Japan, collected between 1986 and 2002. The study researchers examined the association between SBP and antihypertensive medication and lifestyle factors such as BMI, physical activity, alcohol consumption, cigarette smoking, and dietary salt intake. All analyses were performed separately by sex due to different trends in the key variables.

Research objective

The objective of the study was to assess the relationships between the observed drop in mean SBP in Japan between 1986 and 2002 and the use of antihypertensive treatment and lifestyle factors. Prior to this study, the factors that contributed to the decline of mean SBP had not been investigated. Understanding why mean SBP has been decreasing is crucial for public health policy, and this study is part of ongoing work by IHME to better understand the current state of population health.

Recommendations for future work

The researchers suggest that formulating effective policies to stop the trend of overweight and obesity is urgent to further decrease mean SBP and the disease burden from cardiovascular disease, particularly in Japanese men. Continued efforts should be taken to encourage maintaining adequate body weight, keeping alcohol consumption and salt intake to a minimum, and improving the management of hypertension. Data on variables that were unavailable for this study (such as educational background, marital status, occupation, income, urban/rural dwelling, psychosocial factors, and birth weight) should be collected and incorporated into future research models.