Threshold of BMI for the Development of Hypertension among Japanese Adults

Abstract

Background: The optimal value of BMI for the development of hypertension and the influence of BMI on the development of stage 1 or stage 2 hypertension remain unclear.

Objectives: We sought to identify the BMI threshold for the prevention of hypertension and how changes in BMI would influence the risk of developing hypertension.

Methods: We analyzed 1,262,356 participants (median age: 43 y; 50.9% men) with normal blood pressure [BP; systolic BP (SBP) <120 mmHg and diastolic BP (DBP) <80 mmHg] or elevated BP (SBP: 120-129 mmHg and DBP <80 mmHg). The primary outcome was stage 1 (SBP 130-139 mmHg or DBP 80-89 mmHg) or stage 2 hypertension (SBP ≥140 mmHg or DBP ≥90 mmHg). We analyzed the relation between baseline BMI, change in BMI, and the risk of developing hypertension using generalized additive models with a smoothing spline.

Results: During the median follow-up of 851 d, 341,212 cases of stage 1 hypertension and 70,968 cases of stage 2 hypertension were detected. The risk of developing stage 1 or stage 2 hypertension increased steeply after BMI (kg/m²) exceeded 20. The annual change in BMI was positively correlated with the risk of developing stage 1 or 2 hypertension. Contour mapping using generalized additive models demonstrated an additive increase in the risk of developing hypertension with higher baseline BMI and increases in BMI over 1 y. Body-weight gain increases the risk of developing hypertension even in underweight or normal-weight individuals based on the WHO classification.

Conclusions: In Japanese adults with normal or elevated BP, the risk of developing hypertension increased with BMI when baseline BMI was >20. Body-weight gain additively interacted with baseline BMI during hypertension development. Our results underscore the importance of maintaining body weight in preventing the development of hypertension.

Keywords: BMI; body mass index; body weight change; hypertension; prevention.