Changes of Body Mass Index and the Incidence of Hypertension in Late Middle Age: A Nationwide Cohort Study in South Korea

Background: Previous studies revealed weight gain is an independent risk factor for hypertension. Hypertension in late middle age increases the risks of dementia and cardiovascular diseases. We aimed to analyze the difference in the risk of hypertension in the late middle age according to the change of body mass index (BMI) using nationwide cohort data of South Korea.Methods: We used 64,136 individuals from National Health Insurance Service-Health Screening Cohort in South Korea. The primary endpoint is newly diagnosed hypertension after observation start date, which was defined as the date of first examination after 50. BMI changes were measured between two consecutive health examinations before and after 50. Cox proportional hazard regression analysis was performed to evaluate the association between the change of BMI and the risk of hypertension.Results: During the mean follow-up period of 3.4±1.9 years, 8,676 individuals were diagnosed with hypertension. Both normal-to-obese group and obese-to-obese group had 19% higher risk for hypertension, and obese-to normal group had 10% higher risk for hypertension in late middle age, compared to normal-to-normal group.Conclusions: We confirmed becoming obese and maintaining obese increase the risk of hypertension in late middle age. Thus, clinicians need to assess obese patients regularly for the possibility of new onset hypertension and take preventive measure to reduce the risk by losing weights before late middle age.