Naik Abhijit S, Sakhuja Ankit, Cibrik Diane M, Ojo Akinlolu O, Samaniego-Picota Milagros D, Lentine Krista L
1 Section of Nephrology, University of Michigan, Ann Arbor, MI. 2 Center for Outcomes Research and Division of Abdominal Transplantation, Saint Louis University, St. Louis, MO.
Transplantation. 2016 Sep;100(9):1963-9. doi: 10.1097/TP.0000000000000983.
The impact of pretransplant body mass index (BMI) on long-term allograft outcomes after kidney transplantation remains controversial. The conventional approach of using Kaplan-Meier method to calculate the cumulative risk of death-censored allograft failure may overestimate the risk of failure especially when competing failure risks are present.
A retrospective cohort of adult first-time kidney transplant recipients was drawn from the Organ Procurement and Transplantation Network database (2001 to 2009). Based on World Health Organization obesity classification, BMI was categorized as: less than 18.5, 18.5 to <25, 25 to < 30, 30 to < 35, 35 to <40 and ≥40 kg/m. Both unadjusted and adjusted risk models were used to assess for risk of allograft failure in the presence of death as a competing event.
A total of 108 654 recipients were studied. In both unadjusted and adjusted models, increasing BMI level was associated with increased risk of long-term allograft failure. In the adjusted model with BMI 18.5 to less than 25 as the reference, the subhazards ratios (SHRs) for BMI were: less than 18.5: SHR, 0.96; P = 0.41; 25 to less than 30: SHR, 1.05; P = 0.01; 30 to less than 35: SHR, 1.15; P = <0.001; 35 to less than 40: SHR, 1.21; P < 0.001; and greater than 40: SHR, 1.13; P = 0.002.
Handling of death as a competing event demonstrates a graded, detrimental impact of increasing pretransplant BMI on the risk of graft failure after kidney transplantation in both unadjusted and adjusted models. Compared with previous studies, a lower BMI was not associated with an increased risk of graft loss in a competing risk model.
肾移植前体重指数（BMI）对肾移植后长期移植物结局的影响仍存在争议。使用Kaplan-Meier方法计算死亡删失的移植物失败累积风险的传统方法可能会高估失败风险，尤其是在存在竞争性失败风险时。
从器官获取与移植网络数据库（2001年至2009年）中选取成年首次肾移植受者的回顾性队列。根据世界卫生组织肥胖分类，BMI分为：小于18.5、18.5至<25、25至<30、30至<35、35至<40和≥40kg/m²。使用未调整和调整的风险模型来评估在存在死亡作为竞争事件的情况下移植物失败的风险。
共研究了108654名受者。在未调整和调整模型中，BMI水平升高均与长期移植物失败风险增加相关。在以BMI 18.5至小于25为参照的调整模型中，BMI的亚风险比（SHR）分别为：小于18.5：SHR，0.96；P = 0.41；25至小于30：SHR，1.05；P = 0.01；30至小于35：SHR，1.15；P =<0.001；35至小于40：SHR，1.21；P < 0.001；大于40：SHR，1.13；P = 0.002。
将死亡作为竞争事件处理表明，在未调整和调整模型中，移植前BMI升高对肾移植后移植物失败风险具有分级的有害影响。与先前的研究相比，在竞争风险模型中较低的BMI与移植物丢失风险增加无关。
