Obesity in Older Adults and Associations with Cardiovascular Structure and Function

Introduction: Body mass index (BMI), despite being widely used as a marker of obesity, fails to fully capture cardiovascular risks as it is an insufficient biomarker of abdominal adiposity, unlike waist circumference (WC). We aimed to characterize associations between BMI and WC with cardiovascular structure and function in older adults. Methods: Among an observational cohort study of a community of older adults, transthoracic echocardiography determined cardiovascular structure and function, while aerobic capacity was determined by peak oxygen uptake (VO2) metrics. The cut-offs for obesity were 27.5 kg/m(2) for BMI, and >90 cm for males and >80 cm for females for WC. Results: Of 970 older adults without cardiovascular disease (mean age 73 +/- 4 years, 432 [44%] males), 124 (12.8%) were obese by BMI definition while 347 (35.7%) were obese by WC definition. Inter-definitional agreement was fair (Cohen's kappa = 0.345). Unlike the BMI definition, participants defined as obese by WC were more likely to be women (65% vs. 50%, p < 0.001), older (65 +/- 11 vs. 63 +/- 14 years, p = 0.007), and had lower handgrip strength (24 +/- 0.6 vs. 26 +/- 0.4 kg, p = 0.022). Across BMI categories, high WC was associated with more impaired myocardial relaxation (E/A), and VO2 measurements (all p < 0.05). Among those with low BMI, high WC was associated with larger left atrial (LA) volumes (p = 0.003). WC, but not BMI, was independently associated with E/A (beta = -0.114, SE -0.114 +/- 0.024, p < 0.001) in regression analysis. Conclusion: WC identified a higher prevalence of obesity, possibly related to central adiposity. Across BMI categories, WC identified more adverse measurements in E/A, aerobic capacity, and LA structure.