Hypertension risk among individuals living in rural areas may depend on the distance of their residence from population centers, according to a study conducted in Japan.

The study included 1,348 individuals in a rural mountainous region in the eastern part of Shimane prefecture who were interviewed face to face by trained staff and had sitting blood pressure measurements taken at a public center. Individuals who lived a moderate and far distance from a population center (Matsue city) had a significant 44% and 78% increased risk of self-reported hypertension (patients reporting that they were taking antihypertensive medication or were under treatment for hypertension without medication) compared with those who lived close to the population center, after adjusting for potential confounders.

However, the association between distance and hypertension risk became nonsignificant when hypertension defined by BP measurement (140/90 mm Hg or higher) was taken into account, Tsuyoshi Hamano, MA, an Associate Professor at Shimane University in Izumo, and colleagues reported online ahead of print in the American Journal of Hypertension.

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For the study, the researchers estimated distance from subjects’ actual home addresses to the population center based on road network data and did not use straight-line distance. “This is because a road network is more complicated in a mountainous region compared with an urban region; therefore, the straight-line distance might be less effective in this kind of research design,” the authors noted.

The researchers noted that they used self-reported hypertension to define the presence of the condition because a BP measurement taken at a public center might increase bias towards a higher BP.

As for why remoteness from a population center might increase hypertension risk, the authors noted that Japanese living in rural areas might consume more traditional Japanese food, which has a higher salt content than the food of people living in urban areas.