Weight cycling and mortality in women

描述(由申请者提供)：我们将在护士健康研究中评估成年女性体重循环与死亡率之间的关系。在过去的二十年里，一些研究报告称，体重减轻、体重变异性和体重骑行与增加健康风险有关。这些与体重循环或减肥相关的不良健康后果的报告让一些人质疑，建议超重的成年人尝试减肥是否明智。尽管大多数早期研究发现死亡或发病风险增加，但后来的研究并不一致。结果的差异可能反映了这样一个事实，即已经使用了各种体重循环或体重变异性的衡量标准，一些研究未能区分有意和无意的减肥。如果无意减肥带来的风险与自愿减肥无关，未能解释减肥的故意可能会导致错误的推断。我们将评估护士健康研究中77021名中老年女性体重循环与死亡率的关系，这些女性在成年后提供了有意减肥的信息，并在完成问题后存活了至少两年。我们将评估是否独立于成年期的净体重增加(众所周知，这会增加死亡风险)，负重循环是否与死亡风险的增加有关。我们将评估因故意减肥而骑自行车和因无意减肥而骑自行车的关联。我们还将评估体重变异性，包括有意和无意的体重减轻和增加，是否会增加死亡风险。在符合分析条件的77021名女性中，4,057人在随访期间死亡，这给了我们极大的力量来检测体重循环和死亡率之间的联系。我们将研究体重状况(即超重或肥胖)或吸烟状况是否会改变这些关联中的任何一个。如果有任何影响修改的证据，我们将进行分层分析。自1976年以来，作为正在进行的队列研究的一部分，前瞻性地跟踪了大量成年女性样本，关于减肥意向的信息，以及足够多的死亡人数，能够很好地确定死亡率的预测因素，这为我们提供了一种独特而有价值的研究设计，将有助于澄清体重循环、体重变异性和死亡率之间的真实本质。

DESCRIPTION (provided by applicant): We will assess the association between weight cycling and mortality among adult women in the Nurses' Health Study. During the past two decades some studies have reported that weight loss, weight variability, and weight cycling are associated with increased health risks. These reports of adverse health outcomes associated with weight cycling or loss have led some to question whether it is prudent to recommend that overweight adults should try to lose weight. Although most of the early studies found an increased risk of mortality or morbidity, the later studies have not been consistent. The discrepancy in results may reflect the fact that a variety of measures of weight cycling or weight variability have been used and some studies failed to differentiate intentional from unintentional weight loss. If unintentional weight loss carries a risk not associated with voluntary weight loss, a failure to account for the intentionality of the weight loss could potentially lead to faulty inference. We will assess the relationship between weight cycling and mortality among 77021 middle-aged and older women in the Nurses' Health Study who provided information on intentional weight losses in their adult life and survived for at least 2 years after completing the questions. We will evaluate whether independent of net weight gain during adulthood, which is known to increase risk of death, weight cycling is associated with an increased risk of mortality. We will assess the association of weight cycling due to intentional weight losses, as well as cycling due to unintentional weight losses. We will also assess whether weight variability, which includes both intentional and unintentional weight losses and gains, increase the mortality risk. Among the 77021 women eligible for the analysis, 4057 died during the following up, giving us excellent power to detect an association between weight cycling and mortality. We will examine whether weight status (i.e., being overweight or obese) or smoking status modifies any of these associations. If there is any evidence of effect modification, we will conduct stratified analyses. The combination of having large sample of adult women followed prospectively since 1976 as part of an ongoing cohort study, information on the intentionality of weight losses, and a sufficient number of deaths to have good power to identify predictors of mortality, provides us with a unique and valuable study design that will help to clarify the true nature of the association of weight cycling, weight variability, and mortality.