Body Weight Trajectories and Mortality among Older Adults

Anna Zajacova, University of Wyoming
Jennifer A. Ailshire, University of Southern California

Extensive literature has documented a U-shaped association between BMI and mortality. This association is interpreted causally despite well-known methodological problems including 'reverse causality' whereby a low body weight is the result of a disease process ending in death. We address shortcomings of the BMI-mortality literature by exploring long-term changes in body weight and subsequent mortality among older adults. Using the 1992-2008 Health and Retirement Survey data with BMI and mortality information, we employ generalized growth mixture models to identify the optimal number of classes of body weight trajectories. We then examine how they relate to mortality in discrete-time survival models. Preliminary results show two classes of body weight trajectories among men and women, one with a declining and one with an increasing body weight. We expect that mortality of the former group will be significantly higher than that of the latter. This study will advance knowledge of the BMI-mortality association.