Inrig Jula K, Sun Jie L, Yang Qinghong, Briley Libbie P, Szczech Lynda A
Department of Medicine, Division of Nephrology, Duke University Medical Center, Durham, NC 27705, USA.
Clin J Am Soc Nephrol. 2006 Jul;1(4):774-9. doi: 10.2215/CJN.00580705. Epub 2006 May 3.
Comparing outcomes related to dialysis modality is complicated by selection bias introduced by patients and physicians. To address the impact of selection bias, this study compared mortality by initial dialysis modality among patients who had ESRD and were placed on the transplant waiting list. This study was a historical prospective cohort of 12,568 patients in the United States who initiated dialysis between May 1, 1995, and October 31, 1998, and were placed on the transplant waiting list before dialysis initiation. Two-year mortality was compared using Kaplan-Meier curves and Cox proportional hazards models that analyzed patients primarily using an intention-to-treat approach and separately censored patients on a modality switch. At 2 yr, the unadjusted mortality rate was 6.6% among peritoneal dialysis (PD) patients compared with 6.9% among hemodialysis (HD) patients (hazard ratio [HR] 1.01; 95% confidence interval [CI] 0.82 to 1.23). After controlling for differences in baseline characteristics, comorbidities, and laboratory variables, the selection of PD versus HD remained associated with a similar 2-yr mortality risk (HR 1.03; 95% CI 0.83 to 1.28). In separate models, 2-yr mortality associated with PD versus HD was significant among patients with body mass index (BMI) > or = 26 kg/m2 (HR 1.37; 95% CI 1.01 to 1.83) but not among patients with BMI < 26 kg/m2 (HR 0.81; 95% CI 0.61 to 1.07). Results were similar after censoring on a modality switch. In conclusion, although choice of initial dialysis modality seems to be associated with equivalent outcomes among patients who have ESRD and are placed on the transplant waiting list, patients with BMI > or = 26 kg/m2 have increased 2-yr mortality associated with the selection of PD versus HD. Because the interpretation of observational data is highly affected by residual confounding and selection bias, further efforts should focus on the formation and testing of hypotheses to improve dialysis delivery.
患者和医生引入的选择偏倚使与透析方式相关的结果比较变得复杂。为了应对选择偏倚的影响，本研究比较了终末期肾病（ESRD）患者且已列入移植等待名单者按初始透析方式分组的死亡率。本研究是一项针对美国12568例患者的历史性前瞻性队列研究，这些患者于1995年5月1日至1998年10月31日开始透析，并在透析开始前被列入移植等待名单。使用Kaplan-Meier曲线和Cox比例风险模型比较两年死亡率，这些模型主要采用意向性分析方法对患者进行分析，并对转为其他透析方式的患者进行单独截尾分析。在2年时，腹膜透析（PD）患者的未调整死亡率为6.6%，而血液透析（HD）患者为6.9%（风险比[HR]1.01；95%置信区间[CI]0.82至1.23）。在控制了基线特征、合并症和实验室变量的差异后，选择PD与HD相比，两年死亡风险仍然相似（HR 1.03；95%CI 0.83至1.28）。在单独的模型中，体重指数（BMI）≥26 kg/m²的患者中，与HD相比，PD相关的两年死亡率显著（HR 1.37；95%CI 1.01至1.83），而BMI<26 kg/m²的患者中则不显著（HR 0.81；95%CI 0.61至1.07）。在对透析方式转换进行截尾分析后，结果相似。总之，虽然对于ESRD患者且已列入移植等待名单者，初始透析方式的选择似乎与等效结局相关，但BMI≥26 kg/m²的患者中，选择PD与HD相比，两年死亡率增加。由于观察性数据的解释受残余混杂和选择偏倚的影响很大，应进一步努力聚焦于假设的形成和检验，以改善透析治疗。
