Metabolically Healthy Obesity and the Risk of Cardiovascular Disease in the General Population ― Analysis of a Nationwide Epidemiological Database ―

Background Obesity and metabolic disorders frequently coexist, and both are established risk factors for cardiovascular disease (CVD). Although the phenotype of obesity without metabolic disorders, referred to as metabolically healthy obesity (MHO), is attracting clinical interest, the pathophysiological impact of MHO remains unclear.Methods and Results:Using the Japan Medical Data Center database, we studied 802,288 subjects aged ≥20 years without any metabolic disorders or a prior history of CVD. MHO, defined as obesity (body mass index ≥25 kg/m2) with no metabolic disorders, was observed in 9.8% of the study population. The subjects' mean (±SD) age was 42.8±9.4 years and 44.7% were men. The mean follow-up period was 1,126±849 days. Multivariable Cox regression analysis showed that MHO alone did not significantly increase the risk of any CVD. However, abdominal obesity alone increased the risk of heart failure and atrial fibrillation. Moreover, the coexistence of MHO and abdominal obesity increased the risk of myocardial infarction, angina pectoris, heart failure, and atrial fibrillation. The incidence of stroke was not associated with the presence of MHO and abdominal obesity. Conclusions Among individuals with no metabolic disorders, MHO alone did not significantly increase the subsequent CVD risk. However, individuals with comorbid MHO and abdominal obesity had a higher risk of myocardial infarction, angina pectoris, heart failure, and atrial fibrillation, suggesting the prognostic importance of abdominal obesity in subjects with MHO.