Abstract 10371: Body Composition and Mortality in a Large Cohort With Preserved Ejection Fraction- Untangling the "Obesity Paradox"
Background: In several cardiac diseases and in the elderly population, an inverse relationship between obesity, as determined by body mass index (BMI) , and subsequent prognosis has been demonstrated (the “obesity paradox”). However, some have postulated that it is the lean mass index (LMI) component that is beneficial, and that body fat (BF) is, in fact, detrimental. In addition, the mortality-BMI curve is U shaped, where the subjects with very high BMI seem to have a higher mortality.
Patients and Methods: We retrospectively assessed 47866 patients with a preserved left ventricular ejection fraction (LVEF; ≥50%). We calculated BF as determined by the Jackson Pollock equation and LMI as (1-BF) x BMI. The population was divided based on gender adjusted BMI and LMI classifications and gender adjusted BF tertiles. The population was analyzed by total mortality over average 3.1-year follow-up by National Death Index.
Results: In the entire population, higher BMI was narrowly associated (HR 0.99; p<0.0001) with lower mortality. Higher LMI group was clearly protective (HR 0.71; p<0.0001), while BF tertile was only associated with lower mortality if no adjustment was made for LMI group (HR BF tertile 0.87 (p<0.0001) without LMI group; HR 0.97 (p 0.23) after adjustment). Similarly in the lean subjects, low BMI was clearly associated with higher mortality (HR 0.92;p<0.0001), and lower BF tertile was associated with lower mortality only if no adjustment was made for LMI (HR BF tertile 0.80 (p<0.0001) without LMI group; HR 1.01 (p 0.83) after adjustment). The underweight by BF seemed to have an increased mortality (HR 1.91 CI 1.56-2.34) that was independent of LMI. In the obese, however, both BMI (HR 1.03; p<0.0001) and BF (HR 1.18;p 0.0025) were associated with higher mortality, even after adjusting for LMI, which remained protective (HR 0.57;p<0.0001) independently of BF.
Conclusions: Body composition could explain the U shape of the mortality curve seen with increasing BMI. BF seems to be protective in this cohort only when not adjusting for LMI, although being underweight by BF seems to be an independent risk factor. LMI seems to remain protective in the obese even when BMI is not.
- © 2013 by American Heart Association, Inc.