RATIONALE & OBJECTIVE The kidney allocation system (KAS250), using circle-based distribution, attempts to address geographic disparities through broader sharing of deceased-donor kidney allografts. This study sought to evaluate the association between KAS250 and likelihood of deceased-donor kidney transplantation (DDKT) among waitlisted candidates, and whether the policy has differentially affected centers with shorter vs. longer waiting time. STUDY DESIGN Retrospective cohort study. SETTING & Participants: 160,941 candidates waitlisted at 176 transplant centers between 3/2017-3/2024. EXPOSURE KAS250 allocation policy. OUTCOME Rate of DDKT. ANALYTICAL APPROACH Multivariable Cox regression, modeling KAS250 as a time-dependent variable. RESULTS KAS250 was not independently associated with likelihood of DDKT overall (HR=1.01 vs. pre-KAS250, 95% C.I. 0.97-1.04). KAS250's association with likelihood of DDKT varied across centers from HR=0.18 (DDKT less likely after KAS250) to HR=17.12 (DDKT more likely) and varied even among neighboring centers. KAS250 was associated with decreased DDKT at 25.6% and increased DDKT at 18.2% of centers. Centers with previously long median waiting times (57+ months) experienced increased likelihood of DDKT after KAS250 (HR=1.20, 95% C.I. 1.15-1.26), whereas centers with previously short median waiting times (6-24mo.; HR=0.88, 0.84-0.92) experienced decreased likelihood of DDKT. LIMITATIONS Retrospective study of allocation policy changes, confounded by multiple changes over the study timeframe. CONCLUSION Association between KAS250 and DDKT varied across centers. For one-in-four centers, DDKT was less likely after KAS250 relative to pre-KAS250 trends. Candidates at centers with previously long waiting times experienced increased likelihood of DDKT after KAS250. Thus, broader distribution of kidneys may be associated with improved equity in access to DDKT, but additional strategies may be needed to minimize disparities between centers.

中文翻译：

---

基于循环的肾脏分配、中心等待时间和已故捐赠者肾脏移植的可能性之间的关联。


基本原理和目标 肾脏分配系统 (KAS250) 采用基于循环的分配，试图通过更广泛地共享已故捐赠者同种异体肾脏移植物来解决地理差异。本研究旨在评估 KAS250 与候补候选人中死亡供体肾移植 (DDKT) 的可能性之间的关联，以及该政策是否对等待时间较短和较长的中心产生不同的影响。研究设计回顾性队列研究。设置和参与者：2017 年 3 月至 2024 年 3 月期间，176 个移植中心有 160,941 名候选者在候补名单上。曝光KAS250分配政策。 DDKT 的结果率。分析方法 多变量 Cox 回归，将 KAS250 建模为随时间变化的变量。结果 KAS250 与 DDKT 总体可能性并不独立相关（相对于 KAS250 之前，HR=1.01，95% CI 0.97-1.04）。 KAS250 与 DDKT 可能性的关联因中心而异，从 HR=0.18（KAS250 后 DDKT 可能性较小）到 HR=17.12（DDKT 可能性较大），甚至在邻近中心之间也存在差异。在 25.6% 的中心中，KAS250 与 DDKT 降低相关，在 18.2% 的中心中与 DDKT 升高相关。先前中位等待时间较长（57 个月以上）的中心在 KAS250 后经历 DDKT 的可能性增加（HR=1.20，95% CI 1.15-1.26），而先前中位等待时间较短的中心（6-24 个月；HR=0.88， 0.84-0.92) 经历 DDKT 的可能性降低。局限性 对分配政策变化的回顾性研究，受到研究时间范围内的多次变化的影响。结论 KAS250 和 DDKT 之间的关联因中心而异。对于四分之一的中心，与 KAS250 之前的趋势相比，KAS250 之后 DDKT 的可能性较小。 之前等待时间较长的中心的考生在 KAS250 后经历 DDKT 的可能性增加。因此，更广泛的肾脏分布可能与获得 DDKT 的公平性提高有关，但可能需要采取其他策略来尽量减少中心之间的差异。