BACKGROUND: 

The rise in obesity in the United States, along with improvements in antiviral therapies, has led to an increase in the number of obese patients receiving liver transplants. Currently, obesity is a relative contraindication for liver transplant, although exact body mass index (BMI) limits continue to be debated. Studies conflict regarding outcomes in obese patients, while some argue that BMI should not be used as an exclusion criterion at all. Therefore, this retrospective study—utilizing a large national database—seeks to elucidate the association between recipient BMI and hospital length of stay and mortality following liver transplant.

METHODS: 

A retrospective study was conducted using the United Network for Organ Sharing Standard Transplant Analysis and Research database. Fine-Gray competing risk regressions were used to explore the association between BMI and rate of discharge, which varies inversely with length of stay. In our model, subdistribution hazard ratio (SHR) represented the relative change in discharge rate compared to normal BMI, with in-hospital death was considered as a competing event for live discharge. Cox proportional hazard models were built to assess the association of BMI category on all-cause mortality after liver transplantation. Cluster-robust standard errors were used in all analyses to construct confidence intervals.

RESULTS: 

Within the final sample (n = 47,038), overweight (≥25 and <30 kg/m²) patients comprised the largest BMI group (34.7%). The competing risk regression model showed an association for increased length of stay among underweight (SHR = 0.82, 95% confidence interval [CI], 0.77–0.89; P < .001) and class 3 obesity patients (SHR = 0.88, 95% CI, 0.83–0.94; P < .001), while overweight (SHR = 1.05, 95% CI, 1.03–1.08; P < .001) and class 1 obesity (SHR = 1.04, 95% CI, 1.01–1.07; P = .01) were associated with decreased length of stay. When the sample excluded patients with low pretransplant functional status, however, length of stay was not significantly shorter for overweight and obesity class 1 patients. Cox proportional hazard models demonstrated increased survival among overweight, class 1 and class 2 obesity patients and decreased survival among underweight patients.

CONCLUSIONS: 

Our results provide evidence that overweight and obesity class 1 are associated with decreased length of stay and mortality following liver transplant, while underweight and obesity class 3 are associated with prolonged length of stay. Pretransplant functional status may contribute to outcomes for overweight and class 1 obese patients, which necessitates continued investigation of the isolated impact of BMI in those who have had a liver transplant.

中文翻译：

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肥胖与更好的肝移植结果有关吗？肝移植术后住院时间和死亡率的回顾性研究

背景： 

美国肥胖率的上升以及抗病毒疗法的改进导致接受肝移植的肥胖患者数量增加。目前，肥胖是肝移植的相对禁忌症，尽管确切的体重指数（BMI）限制仍然存在争议。关于肥胖患者的结果的研究存在冲突，而一些人认为 BMI 根本不应该用作排除标准。因此，这项回顾性研究利用大型国家数据库，旨在阐明受者 BMI 与肝移植后住院时间和死亡率之间的关系。

方法： 

使用器官共享标准移植分析和研究联合网络数据库进行了一项回顾性研究。Fine-Gray 竞争风险回归用于探索 BMI 与出院率之间的关联，出院率与住院时间成反比。在我们的模型中，次分布风险比（SHR）代表出院率与正常体重指数相比的相对变化，院内死亡被认为是实时出院的竞争事件。建立 Cox 比例风险模型来评估 BMI 类别与肝移植后全因死亡率的关联。所有分析中均使用聚类稳健标准误来构建置信区间。

结果： 

在最终样本中（n = 47,038），超重（≥25 且<30 kg/m ²）患者构成了最大的BMI 组（34.7%）。竞争风险回归模型显示，体重不足（SHR = 0.82，95% 置信区间 [CI]，0.77–0.89； P < .001）和 3 级肥胖患者（SHR = 0.88，95% CI）与住院时间延长存在关联。，0.83–0.94；P < .001），而超重（SHR = 1.05，95% CI，1.03–1.08；P < .001）和 1 级肥胖（SHR = 1.04，95% CI，1.01–1.07；P = .01) 与住院时间缩短有关。然而，当样本排除移植前功能状态较低的患者时，超重和肥胖 1 级患者的住院时间并没有显着缩短。Cox比例风险模型表明，超重、1级和2级肥胖患者的生存率增加，而体重不足的患者生存率下降。

结论： 

我们的研究结果提供证据表明，超重和肥胖 1 级与肝移植后住院时间和死亡率降低相关，而体重不足和肥胖 3 级与住院时间延长相关。移植前的功能状态可能会影响超重和 1 级肥胖患者的预后，因此有必要继续研究 BMI 对肝移植患者的单独影响。