Weight cycling and mortality in women

描述（由申请人提供）：我们将评估护士健康研究中成年女性体重循环与死亡率之间的关系。在过去的二十年中，一些研究报告称，体重减轻、体重变化和体重循环与健康风险增加有关。这些与体重循环或减肥相关的不良健康结果的报告导致一些人质疑，建议超重的成年人减肥是否明智。虽然大多数早期研究发现死亡率或发病率增加的风险，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，即使用了各种体重循环或体重变异性的测量方法，并且一些研究未能区分有意和无意的体重减轻。如果无意减肥带来了与自愿减肥无关的风险，那么未能解释减肥的故意性可能会导致错误的推断。我们将评估护士健康研究中77021名中老年妇女的体重循环与死亡率之间的关系，这些妇女提供了成年后有意减肥的信息，并在完成问题后存活了至少2年。我们将评估体重循环是否独立于成年期净体重增加（已知会增加死亡风险）与死亡风险增加相关。我们将评估由于有意减肥而引起的体重循环，以及由于无意减肥而引起的体重循环的关联。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，有4057人在随访期间死亡，这给了我们很好的能力来检测体重循环和死亡率之间的关联。我们将检查体重状况（即超重或肥胖）或吸烟状况是否会改变这些关联。如果有效果改变的证据，我们将进行分层分析。自1976年以来，作为一项正在进行的队列研究的一部分，对成年女性进行了大量的前瞻性随访，获得了有关体重减轻的意向性的信息，并获得了足够数量的死亡病例，这为我们提供了一种独特而有价值的研究设计，有助于阐明体重循环、体重变异性和死亡率之间关系的真实本质。

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.