Abstract
Background/ObjectivesThe relationship between body mass index (BMI) and mortality remains controversial. Furthermore, the association between BMI and cardiovascular events (CVE) is not conclusive and may differ by ethnicity. We aimed to estimate the associations between the BMI and mortality or cardiovascular disease in a general Korean population.Subjects/MethodsThis study was based on a sample cohort database released by the Korean National Health Insurance Service. We analyzed a total of 415,796 adults older than 30 years of age who had undergone a national health examination at least once from 2002 to 2012. Hazard ratios for death and cardiovascular events were calculated using Cox proportional hazards models.ResultsFor both men and women, BMI and overall mortality showed a U-shaped association, with the lowest mortality rate among those with a BMI of 25–27.4 kg/m2. Compared with them, subjects with a BMI ≥ 30kg/m2, men with a BMI < 25 kg/m2, and women with a BMI < 22.5 kg/m2 showed significantly higher overall mortality. Additionally, men with a BMI < 22.5 kg/m2 and women with a BMI < 20 kg/m2 displayed an increased risk of cardiovascular mortality. Unlike the mortality trend, the CVD events trend showed a linearly positive association. The risk of a CVE was the lowest in men with a BMI ranging from 20 to 22.4 kg/m2 and in women with a BMI < 20 kg/m2.ConclusionsThe BMI showed a U-shaped association with overall mortality, where slightly obese subjects showed the lowest rate of mortality. The CVE exhibited a linear association with the BMI, where the lowest risk was observed for normal weight subjects in a general Korean population.
Highlights
The prevalence of individuals who are overweight or obese has increased worldwide
The body mass index (BMI) showed a U-shaped association with overall mortality, where slightly obese subjects showed the lowest rate of mortality
BMI, where the lowest risk was observed for normal weight subjects in a general Korean population
Summary
The prevalence of individuals who are overweight or obese has increased worldwide. Obesity is closely associated with metabolic diseases, including type 2 diabetes mellitus (DM), hypertension (HTN), and cardiovascular diseases (CVD), which are the leading causes of death [1]. In contrast to conventional beliefs that obesity and overweight status are associated with increased mortality, a previous study showed that overweight status could decrease all-cause mortality [2]. In studies of East Asian populations, a U-shaped relationship between BMI and mortality was reported, and individuals with a BMI ranging from 18.5 to 27.5 kg/m2 displayed the lowest risk of overall mortality [3,4,5,6]. In a large meta-analysis study, mild obesity was not associated with higher mortality rates, and overweight status was associated with a significantly lower risk of all-cause mortality [7]. In Korea, subjects who were overweight or mildly obese showed the lowest risk of all-cause mortality [3, 8]. When considering the relationship between BMI and mortality, the reverse causality could be a significant limitation. To reduce the reverse causality, previous studies suggested the possible solution such as the exclusion of smokers, subjects who already have some chronic disease, and participants dying within five years of recruitment. [9]
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