Danish Cancer Society Research Center, Copenhagen, Denmark.
The Stroke Unit, Frederiksberg University Hospital, Frederiksberg, Denmark.
JAMA Neurol. 2014 Aug;71(8):978-84. doi: 10.1001/jamaneurol.2014.1017.
Reports of an obesity paradox have led to uncertainty about secondary prevention in obese patients with stroke. The paradox is disputed and has been claimed to be an artifact due to selection bias.
To determine whether the obesity paradox in stroke is real or an artificial finding due to selection bias.
DESIGN, SETTING, AND PARTICIPANTS: We studied survival after stroke in relation to body mass index (BMI, calculated as weight in kilograms divided by height in meters squared). To overcome selection bias, we studied only deaths caused by the index stroke on the assumption that death by stroke reported on a death certificate was due to the index stroke if death occurred within the first month poststroke. We used the Danish Stroke Register, containing information on all hospital admissions for stroke in Denmark from 2003 to 2012, and the Danish Registry of Causes of Death. The study included all registered Danes (n = 71 617) for whom information was available on BMI (n = 53 812), age, sex, civil status, stroke severity, stroke subtype, a predefined cardiovascular profile, and socioeconomic status.
The independent relation between BMI and death by the index stroke within the first week or month by calculating hazard ratios in multivariate Cox regression analysis and multiple imputation for cases for whom information on BMI was missing.
Of the 71 617 patients, 7878 (11%) had died within the first month; of these, stroke was the cause of death of 5512 (70%). Of the patients for whom information on BMI was available, 9.7% were underweight, 39.0% were of normal weight, 34.5% were overweight, and 16.8% were obese. Body mass index was inversely related to mean age at stroke onset (P < .001). There was no difference in the risk for death by stroke in the first month among patients who were normal weight (reference), overweight (hazard ratio, 0.96; 95% CI, 0.88-1.04), and obese (hazard ratio, 1.0; 95% CI, 0.88-1.13). Analysis of deaths within 1 week gave similar results.
We found no evidence of an obesity paradox in patients with stroke. Stroke occurred at a significantly younger age in patients with higher BMI. Hence, obese patients with stroke should continue to aim for normal weight.
肥胖悖论的报告导致人们对肥胖的中风患者的二级预防产生了不确定性。这种悖论存在争议，并且由于选择偏差而被认为是人为的。
确定中风患者的肥胖悖论是否是真实存在的，还是由于选择偏差而导致的人为发现。
设计、环境和参与者：我们研究了体重指数（BMI，体重除以身高的平方）与中风后生存之间的关系。为了克服选择偏差，我们仅研究了索引中风引起的死亡，假设死亡证明上报告的中风死亡是由于索引中风，如果在中风后第一个月内发生死亡。我们使用了丹麦中风登记处，该登记处包含了 2003 年至 2012 年丹麦所有医院因中风入院的信息，以及丹麦死因登记处。该研究包括所有注册的丹麦人（n=71617），他们的 BMI（n=53812）、年龄、性别、婚姻状况、中风严重程度、中风类型、预先定义的心血管特征和社会经济地位信息均可获得。
通过在多变量 Cox 回归分析中计算危险比，并对 BMI 信息缺失的病例进行多重插补，来确定 BMI 与索引中风在第一周或一个月内死亡的独立关系。
在 71617 名患者中，7878 人（11%）在第一个月内死亡；其中，5512 人（70%）的死亡原因是中风。在有 BMI 信息的患者中，9.7%体重不足，39.0%体重正常，34.5%超重，16.8%肥胖。BMI 与中风发病时的平均年龄呈负相关（P<0.001）。在体重正常（参考）、超重（危险比，0.96；95%置信区间，0.88-1.04）和肥胖（危险比，1.0；95%置信区间，0.88-1.13）的患者中，第一个月中风死亡的风险没有差异。分析一周内的死亡情况得到了类似的结果。
我们没有发现中风患者存在肥胖悖论的证据。BMI 较高的中风患者发病年龄明显较轻。因此，患有中风的肥胖患者应继续努力保持正常体重。
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