Supplementary Material for: Association between timing of vascular access creation and mortality in patients initiating hemodialysis: A nationwide cohort study in Japan

Introduction: The optimal time for vascular access (VA) creation remains controversial. Methods: We conducted a cohort study using data from the Japanese Society for Dialysis Therapy Renal Data Registry. Adult patients who started receiving hemodialysis in 2007 and had a permanent VA created were included. The exposure of interest was the timing of VA creation, categorized into three groups: early VA creation (defined as creation at least 4 months before hemodialysis initiation), just prior VA creation (creation between 1 and 3 months before hemodialysis initiation), and late VA creation (creation within 1 month of or after hemodialysis initiation). Cox regression analyses were used to compare 1-year all-cause mortality, with late VA creation as the reference group. Owing to the violations of the proportional hazards assumptions, the follow-up period was divided into ‘early’ (1–4 months follow-up) and ‘late’ (5–12 months follow-up) periods. Results: Overall, 1,280 (15.4%) of 8,322 patients died. Both early creation and just prior creation were associated with lower all-cause mortality in the early period compared with late creation. In the late period, the hazard ratios (HRs) for all-cause mortality decreased with earlier VA creation (adjusted HRs [95% confidence intervals]: 0.49 [0.35–0.67] for the early creation group and 0.63 [0.51–0.79] for the just prior creation group). Conclusion: Our study suggests that VA creation at least 1 month before hemodialysis initiation is associated with lower all-cause mortality in the early period, with earlier VA creation resulting in further mortality reduction in the late period.

引言：血管通路（vascular access, VA）创建的最佳时机仍存争议。
方法：本研究采用日本透析治疗学会肾脏数据登记库（Japanese Society for Dialysis Therapy Renal Data Registry）的数据开展队列研究。纳入2007年开始接受血液透析且已建立永久性VA的成年患者。研究关注的暴露因素为VA创建时机，分为三组：早期创建组（定义为血液透析开始前至少4个月创建）、近透析前创建组（血液透析开始前1至3个月创建）及晚期创建组（血液透析开始后1个月内或开始时创建）。采用Cox回归分析比较1年全因死亡率，以晚期VA创建组为参照。由于比例风险假设不成立，随访期被分为“早期”（随访1-4个月）和“晚期”（随访5-12个月）两个阶段。
结果：8322例患者中，共1280例（15.4%）死亡。与晚期创建组相比，早期创建组和近透析前创建组在随访早期的全因死亡率更低。在随访晚期，VA创建时机越早，全因死亡率的风险比（hazard ratio, HR）越低（校正后HR值：早期创建组为0.49[95%置信区间0.35-0.67]，近透析前创建组为0.63[95%置信区间0.51-0.79]）。
结论：本研究表明，血液透析开始前至少1个月创建VA与随访早期全因死亡率降低相关，且VA创建时机越早，随访晚期的死亡率降幅越大。