Department of Social and Behavioral Sciences, College of Global Public Health, New York University, New York, New York, United States of America.
Department of Population Health, School of Medicine, New York University, New York, New York, United States of America.
PLoS One. 2017 Dec 7;12(12):e0188636. doi: 10.1371/journal.pone.0188636. eCollection 2017.
Prior work suggests that obesity may confer a survival advantage among persons with cardiovascular disease (CVD). This obesity "paradox" is frequently studied in the context of prevalent disease, a stage in the disease process when confounding from illness-related weight loss and selective survival are especially problematic. Our objective was to examine the association of obesity with mortality among persons with incident CVD, where biases are potentially reduced, and to compare these findings with those based on prevalent disease.
We used data from the Health and Retirement Study, an ongoing, nationally representative longitudinal survey of U.S. adults age 50 years and older initiated in 1992 and linked to Medicare claims. Cox proportional hazard models were used to estimate the association between weight status and mortality among persons with specific CVD diagnoses. CVD diagnoses were established by self-reported survey data as well as Medicare claims. Prevalent disease models used concurrent weight status, and incident disease models used pre-diagnosis weight status.
We examined myocardial infarction, congestive heart failure, stroke, and ischemic heart disease. A strong and significant obesity paradox was consistently observed in prevalent disease models (hazard of death 18-36% lower for obese class I relative to normal weight), replicating prior findings. However, in incident disease models of the same conditions in the same dataset, there was no evidence of this survival benefit. Findings from models using survey- vs. claims-based diagnoses were largely consistent.
We observed an obesity paradox in prevalent CVD, replicating prior findings in a population-based sample with longer-term follow-up. In incident CVD, however, we did not find evidence of a survival advantage for obesity. Our findings do not offer support for reevaluating clinical and public health guidelines in pursuit of a potential obesity paradox.
先前的研究表明，肥胖可能为心血管疾病（CVD）患者带来生存优势。这种肥胖“悖论”在流行疾病的背景下经常被研究，这是疾病过程中的一个阶段，此时与疾病相关的体重减轻和选择性生存相关的混杂因素特别成问题。我们的目的是研究肥胖与 CVD 患者死亡率之间的关系，在这种情况下，偏倚可能会降低，并将这些发现与基于流行疾病的研究进行比较。
我们使用了来自健康与退休研究（Health and Retirement Study）的数据，这是一项正在进行的、对美国 50 岁及以上成年人进行的全国代表性纵向调查，于 1992 年启动，并与医疗保险索赔数据相链接。Cox 比例风险模型用于估计特定 CVD 诊断患者的体重状况与死亡率之间的关系。CVD 诊断是通过自我报告的调查数据以及医疗保险索赔来确定的。流行疾病模型使用同期体重状况，而新发疾病模型使用发病前的体重状况。
我们研究了心肌梗死、充血性心力衰竭、中风和缺血性心脏病。在流行疾病模型中，始终观察到强烈而显著的肥胖悖论（肥胖 I 级相对于正常体重的死亡风险降低 18-36%），这与之前的研究结果一致。然而，在同一数据集相同条件下的新发疾病模型中，没有证据表明这种生存获益。基于调查诊断与基于索赔诊断的模型的结果基本一致。
我们在流行的 CVD 中观察到肥胖悖论，在基于人群的具有更长随访时间的样本中复制了先前的发现。然而，在新发 CVD 中，我们没有发现肥胖对生存的优势。我们的发现不支持为追求潜在的肥胖悖论而重新评估临床和公共卫生指南。
