From Leicester Cardiovascular Biomedical Research Unit and Department of Cardiovascular Sciences, University of Leicester, Glenfield Hospital, UK (G.M., M.J.W., A.G.D., G.F.S., M.N., T.K., G.J.M.); Department of Anaesthesia and Critical Care, Glenfield Hospital, University Hospitals of Leicester NHS Trust, UK (R.P.); and Service of Biometry and Clinical Epidemiology, IRCCS Policlinico San Matteo Foundation, Pavia, Italy (C.K.).
Circulation. 2017 Feb 28;135(9):850-863. doi: 10.1161/CIRCULATIONAHA.116.022840. Epub 2016 Dec 28.
In an apparent paradox, morbidity and mortality are lower in obese patients undergoing cardiac surgery, although the nature of this association is unclear. We sought to determine whether the obesity paradox observed in cardiac surgery is attributable to reverse epidemiology, bias, or confounding.
Data from the National Adult Cardiac Surgery registry for all cardiac surgical procedures performed between April 2002 and March 2013 were extracted. A parallel systematic review and meta-analysis (MEDLINE, Embase, SCOPUS, Cochrane Library) through June 2015 were also accomplished. Exposure of interest was body mass index categorized into 6 groups according to the World Health Organization classification.
A total of 401 227 adult patients in the cohort study and 557 720 patients in the systematic review were included. A U-shaped association between mortality and body mass index classes was observed in both studies, with lower mortality in overweight (adjusted odds ratio, 0.79; 95% confidence interval, 0.76-0.83) and obese class I and II (odds ratio, 0.81; 95% confidence interval, 0.76-0.86; and odds ratio, 0.83; 95% confidence interval, 0.74-0.94) patients relative to normal-weight patients and increased mortality in underweight individuals (odds ratio, 1.51; 95% confidence interval, 1.41-1.62). In the cohort study, a U-shaped relationship was observed for stroke and low cardiac output syndrome but not for renal replacement therapy or deep sternal wound infection. Counter to the reverse epidemiology hypotheses, the protective effects of obesity were less in patients with severe chronic renal, lung, or cardiac disease and greater in older patients and in those with complications of obesity, including the metabolic syndrome and atherosclerosis. Adjustments for important confounders did not alter our results.
Obesity is associated with lower risks after cardiac surgery, with consistent effects noted in multiple analyses attempting to address residual confounding and reverse causation.
在一个明显的悖论中，接受心脏手术的肥胖患者的发病率和死亡率较低，尽管这种关联的性质尚不清楚。我们试图确定心脏手术中观察到的肥胖悖论是否归因于反向流行病学、偏倚或混杂因素。
从 2002 年 4 月至 2013 年 3 月期间进行的所有心脏手术的国家成人心脏手术登记处提取数据。还通过 2015 年 6 月完成了平行的系统评价和荟萃分析（MEDLINE、Embase、SCOPUS、Cochrane 图书馆）。感兴趣的暴露是体重指数（BMI），根据世界卫生组织的分类分为 6 组。
队列研究中共有 401227 名成年患者和系统评价中 557720 名患者纳入研究。在两项研究中，死亡率与 BMI 类别之间均呈 U 形关联，超重（校正比值比，0.79；95%置信区间，0.76-0.83）和 I 级和 II 级肥胖（比值比，0.81；95%置信区间，0.76-0.86；比值比，0.83；95%置信区间，0.74-0.94）患者的死亡率低于正常体重患者，而体重不足患者的死亡率升高（比值比，1.51；95%置信区间，1.41-1.62）。在队列研究中，脑卒中及低心排综合征呈 U 形关系，但肾替代治疗或深部胸骨伤口感染则没有。与反向流行病学假说相反，肥胖的保护作用在患有严重慢性肾、肺或心脏疾病的患者中较小，而在老年患者中和存在肥胖并发症（包括代谢综合征和动脉粥样硬化）的患者中较大。对重要混杂因素进行调整并未改变我们的结果。
肥胖与心脏手术后的低风险相关，多项分析试图解决残留混杂因素和反向因果关系，结果一致。
