Obesity paradox: conditioning on disease enhances biases in estimating the mortality risks of obesity.
Obesity paradox: conditioning on disease enhances biases in estimating the mortality risks of obesity.
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DOI：
10.1097/ede.0000000000000075
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发表时间：
2014-05
期刊：
影响因子：
--
通讯作者：
Stokes A
中科院分区：
文献类型：
--
作者：
Preston SH;Stokes A
补充数字内容可在文本中找到。许多研究已经证明了一个肥胖的悖论--肥胖的生存优势--在被诊断患有某种疾病的人群中。肥胖是否与这些情况下死亡率的提高有因果关系尚不清楚。我们发展了对撞机偏见的逻辑，因为它涉及到吸烟和肥胖之间的关联在患病人群。来自国家健康和营养检查调查（NHANES）的数据被用来调查糖尿病和糖尿病前期（dysplasia）人群中的经验性偏差。我们还使用NHANES来调查是否反向因果通路在精神障碍患者中比在源人群中更突出。考克斯回归分析被用来检查在那些患有精神障碍的人中肥胖悖论的程度。在回归分析中，我们探讨了肥胖和吸烟之间的相互作用，并实施了各种数据限制，旨在减少反向因果关系的程度。我们在精神障碍患者中发现了一个肥胖悖论。在这一人群中，肥胖和吸烟之间的负相关性比源人群强得多，疾病和体重减轻的程度也更大。肥胖悖论在从不吸烟者中并不存在。在吸烟者中，通过不断努力减少反向因果关系的程度，消除了悖论。正常体重的精神障碍患者死亡率较高不是因果关系，而是肥胖和吸烟之间更密切的负相关的产物。
Supplemental Digital Content is available in the text. Many studies have documented an obesity paradox—a survival advantage of being obese—in populations diagnosed with a medical condition. Whether obesity is causally associated with improved mortality in these conditions is unresolved. We develop the logic of collider bias as it pertains to the association between smoking and obesity in a diseased population. Data from the National Health and Nutrition Examination Survey (NHANES) are used to investigate this bias empirically among persons with diabetes and prediabetes (dysglycemia). We also use NHANES to investigate whether reverse causal pathways are more prominent among people with dysglycemia than in the source population. Cox regression analysis is used to examine the extent of the obesity paradox among those with dysglycemia. In the regression analysis, we explore interactions between obesity and smoking, and we implement a variety of data restrictions designed to reduce the extent of reverse causality. We find an obesity paradox among persons with dysglycemia. In this population, the inverse association between obesity and smoking is much stronger than in the source population, and the extent of illness and weight loss is greater. The obesity paradox is absent among never-smokers. Among smokers, the paradox is eliminated through successive efforts to reduce the extent of reverse causality. Higher mortality among normal-weight people with dysglycemia is not causal but is rather a product of the closer inverse association between obesity and smoking in this subpopulation.