Mazimba S, Holland E, Nagarajan V, Mihalek A D, Kennedy J L W, Bilchick K C
Department of Medicine, University of Virginia, Charlottesville, VA, USA.
Department of Medicine, University of Texas Medical Branch, Galveston, TX, USA.
Int J Obes (Lond). 2017 Aug;41(8):1164-1168. doi: 10.1038/ijo.2017.45. Epub 2017 Feb 17.
The 'obesity paradox' refers to the fact that obese patients have better outcomes than normal weight patients. This has been observed in multiple cardiovascular conditions, but evidence for obesity paradox in pulmonary hypertension (PH) remains sparse.
We categorized 267 patients from the National Institute of Health-PH registry into five groups based on body mass index (BMI): underweight, normal weight, overweight, obese and morbidly obese. Mortality was compared in BMI groups using the χ statistic. Five-year probability of death using the PH connection (PHC) risk equation was calculated, and the model was compared with BMI groups using Cox proportional hazards regression and Kaplan-Meier (KM) survival curves.
Patients had a median age of 39 years (interquartile range 30-50 years), a median BMI of 23.4 kg m (21.0-26.8 kg m) and an overall mortality at 5 years of 50.2%. We found a U-shaped relationship between survival and 1-year mortality with the best 1-year survival in overweight patients. KM curves showed the best survival in the overweight, followed by obese and morbidly obese patients, and the worst survival in normal weight and underweight patients (log-rank P=0.0008). In a Cox proportional hazards analysis, increasing BMI was a highly significant predictor of improved survival even after adjustment for the PHC risk equation with a hazard ratio for death of 0.921 per kg m (95% confidence interval: 0.886-0.954) (P<0.0001).
We observed that the best survival was in the overweight patients, making this more of an 'overweight paradox' than an 'obesity paradox'. This has implications for risk stratification and prognosis in group 1 PH patients.
“肥胖悖论”指的是肥胖患者比正常体重患者预后更好这一事实。这一现象已在多种心血管疾病中被观察到，但肺动脉高压（PH）中肥胖悖论的证据仍然稀少。
我们根据体重指数（BMI）将来自美国国立卫生研究院肺动脉高压注册中心的267例患者分为五组：体重过轻、正常体重、超重、肥胖和病态肥胖。使用χ²统计量比较各BMI组的死亡率。使用肺动脉高压关联（PHC）风险方程计算5年死亡概率，并使用Cox比例风险回归和Kaplan-Meier（KM）生存曲线将该模型与BMI组进行比较。
患者的中位年龄为39岁（四分位间距30 - 50岁），中位BMI为23.4kg/m²（21.0 - 26.8kg/m²），5年总死亡率为50.2%。我们发现生存与1年死亡率之间呈U形关系，超重患者1年生存率最佳。KM曲线显示超重患者生存率最佳，其次是肥胖和病态肥胖患者，正常体重和体重过轻患者生存率最差（对数秩检验P = 0.0008）。在Cox比例风险分析中，即使在调整PHC风险方程后，BMI增加仍是生存改善的高度显著预测因素，每kg/m²死亡风险比为0.921（95%置信区间：0.886 - 0.954）（P < 0.0001）。
我们观察到超重患者生存率最佳，这更像是“超重悖论”而非“肥胖悖论”。这对1组肺动脉高压患者的风险分层和预后具有启示意义。
