title: Modeling obesity histories in cohort analyses of health and mortality.
abstract: There is great interest in understanding the role of weight dynamics over the life cycle in predicting the incidence of disease and death. Beginning with a Medline search, we identify, classify, and evaluate the major approaches that have been used to study these dynamics. We identify four types of models: additive models, duration-of-obesity models, additive-weight-change models, and interactive models. We develop a framework that integrates the major approaches and shows that they are often nested in one another, a property that facilitates statistical comparisons. Our criteria for evaluating models are two-fold: the model's interpretability and its ability to account for observed variation in health outcomes. We apply two sets of nested models to data on adults age 50-74 years at baseline in two national probability samples drawn from National Health and Nutrition Examination Survey. One set of models treats obesity as a dichotomous variable and the other treats it as a continuous variable. In three of four applications, a fully interactive model does not add significant explanatory power to the simple additive model. In all four applications, little explanatory power is lost by simplifying the additive model to a duration model in which the coefficients of weight at different ages are set equal to one another. Other versions of a duration-of-obesity model also perform well, underscoring the importance of obesity at early adult ages for mortality at older ages.
authors.affiliation: Population Studies Center, University of Pennsylvania, Philadelphia, PA 19103, USA. spreston@sas.upenn.edu
authors.forename: Samuel H
authors.initials: SH
authors.lastname: Preston
authors.forename: Neil K
authors.initials: NK
authors.lastname: Mehta
authors.forename: Andrew
authors.initials: A
authors.lastname: Stokes
mesh_terms: D000367:Age Factors; D000368:Aged; D015992:Body Mass Index; D005500:Follow-Up Studies; D006304:Health Status; D006801:Humans; D008875:Middle Aged; D008954:Models, Biological; D015233:Models, Statistical; D009749:Nutrition Surveys; D009765:Obesity / Q000150:complications / Q000401:mortality*; D012189:Retrospective Studies; D013997:Time Factors; D014481:United States / Q000453:epidemiology