Is the effect of body mass index on hypertension modified by the elevation? A cross-sectional study of rural areas in Japan

Obesity is an established independent risk factor for developing hypertension. A recent study showed that the effect of obesity on hypertension varies by the elevation of the residence area. Thus, we hypothesized that the interaction effect of body mass index (BMI) and elevation has a significant association with hypertension. The first aim of this cross-sectional study was to examine whether BMI was associated with hypertension, after adjustment for covariates. The second aim was to examine whether the interaction term between BMI and elevation was associated with hypertension, after adjustment for covariates. Data were collected from a cross-sectional study conducted in a rural area of Japan in 2016. After excluding participants with missing data (n = 2), data from 729 participants were analyzed. We found that BMI was significantly associated with hypertension. In addition, the interaction term between BMI and elevation had a significant association with hypertension. The findings of the present study support the recent evidence that high BMI is an independent risk factor for hypertension, but its effect varies by elevation. Thus, context-specific interventions could be an effective approach to prevent hypertension in this area.