ABSTRACT

A key uncertainty in the obesity-mortality association continues to be how this association changes over the life course. Prior studies tend to rely on cross-sectional design with static weight status taken at the time of the survey. This study tracks a cohort of individuals and employs lifelong body mass index information from the Framingham Heart Study original cohort (1948–2010). We focus on respondents who were younger than age 45 at time of their first survey (n = 2,176) and evaluate how the mortality risk associated with obesity changes over three age groups (below 45, 45–59, and 60 and above) and how population compositions may contribute to this pattern. We find the hazard ratio associated with obesity compared to normal weight decreases over three age groups, but this pattern is influenced by different ages of onset of obesity, inconsistency in the reference group (normal weight) over ages, and mortality selection effects. These factors explain away the decreasing effect of obesity (with onset before age 45) on mortality up to age 60; after age 60, the detrimental effect still declines, but to a much less degree. Later onset of obesity, however, is not significantly associated with excess mortality risks after age 60.

摘要

肥胖与死亡率关联的一个关键不确定性仍然是这种关联在整个生命过程中如何变化。先前的研究往往依赖于在调查时采用静态重量状态的横截面设计。该研究跟踪一组个体，并使用来自弗雷明汉心脏研究原始队列（1948-2010）的终生体重指数信息。我们关注第一次调查时年龄小于 45 岁的受访者 ( n= 2,176) 并评估与肥胖相关的死亡风险如何在三个年龄组（45 岁以下、45-59 岁和 60 岁及以上）中发生变化，以及人口构成如何促成这种模式。我们发现与肥胖相关的风险比在三个年龄组中与正常体重相比有所降低，但这种模式受到不同肥胖发病年龄、参考组（正常体重）随年龄的不一致以及死亡率选择效应的影响。这些因素解释了肥胖（在 45 岁之前发病）对 60 岁以下死亡率降低的影响；60 岁以后，不利影响仍在下降，但程度要小得多。然而，较晚发生的肥胖与 60 岁以后的额外死亡风险没有显着相关性。