Normal-Weight Central Obesity: Implications for Total and Cardiovascular Mortality

Background: The relationship between central obesity and survival in community-dwelling adults with normal body mass index (BMI) is not well-known. Objective: To examine total and cardiovascular mortality risks associated with central obesity and normal BMI. Design: Stratified multistage probability design. Setting: NHANES III (Third National Health and Nutrition Examination Survey). Participants: 15 184 adults (52.3% women) aged 18 to 90 years. Measurements: Multivariable Cox proportional hazards models were used to evaluate the relationship of obesity patterns defined by BMI and waist-to-hip ratio (WHR) and total and cardiovascular mortality risk after adjustment for confounding factors. Results: Persons with normal-weight central obesity had the worst long-term survival. For example, a man with a normal BMI (22 kg/m(2)) and central obesity had greater total mortality risk than one with similar BMI but no central obesity (hazard ratio [HR], 1.87 [95% CI, 1.53 to 2.29]), and this man had twice the mortality risk of participants who were overweight or obese according to BMI only (HR, 2.24 [CI, 1.52 to 3.32] and 2.42 [CI, 1.30 to 4.53], respectively). Women with normal-weight central obesity also had a higher mortality risk than those with similar BMI but no central obesity (HR, 1.48 [CI, 1.35 to 1.62]) and those who were obese according to BMI only (HR, 1.32 [CI, 1.15 to 1.51]). Expected survival estimates were consistently lower for those with central obesity when age and BMI were controlled for. Limitations: Body fat distribution was assessed based on anthropometric indicators alone. Information on comorbidities was collected by self-report. Conclusion: Normal-weight central obesity defined by WHR is associated with higher mortality than BMI-defined obesity, particularly in the absence of central fat distribution.