Effects of long- and short-term body mass index changes on incident hypertension are different

The aim of this study was to evaluate hypertension risk associated with long- and short-term body mass index (BMI) changes.

This prospective cohort study included four examinations: 2004 to 2006, 2008, 2010, and 2017. Adjusted Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of BMI changes on incident hypertension. The difference of β coefficients between long- and short-term BMI changes were examined using Fisher Z-test.

Relative to stable, normal BMI, both long- and short-term elevated BMI conferred an increased risk for hypertension, with HRs of 1.507 (95% CI, 1.286-1.767) and 1.197(95% CI, 1.019-1.405), respectively. In contrast, relative to stable overweight, both long- and short-term decreased BMI conferred a reduced risk for hypertension, with HRs of 0.651(95% CI, 0.536-0.789) and 0.775 (0.625-0.962), respectively. Additionally, for BMI changing from normal to overweight, long-term changes were relatively more strongly associated with increased risk for incident hypertension than short-term based on regression coefficients (β = 0.410 versus β = 0.179, P < 0.001). For BMI changing from overweight to normal, long-term changes were relatively more strongly associated with lower risk than short-term based on regression coefficients (β = -0.430 versus β = -0.254, P = 0.007). Additionally, there was no correlation between absolute changes in BMI and systolic blood pressure for long- (P = 0.744) and short-term (P = 0.097).

For participants with normal BMI, risk tended to be higher in adults whose elevated BMI occurred during the long-term. For those who are overweight, long-term decreased BMI can reduce the risk for incident hypertension to a greater extent. No correlation was found between absolute changes in BMI and systolic blood pressure.