Supplementary Material for: Comparison of Outcomes of In-Centre Haemodialysis Patients between the 1st and 2nd COVID-19 Outbreak in England, Wales, and Northern Ireland: A UK Renal Registry Analysis

Introduction: This retrospective cohort study compares in-centre haemodialysis (ICHD) patients’ outcomes between the 1st and 2nd waves of the COVID-19 pandemic in England, Wales, and Northern Ireland. Methods: All people aged ≥18 years receiving ICHD at 31 December 2019, who were still alive and not in receipt of a kidney transplant at 1 March and who had a positive polymerase chain reaction test for SARS-CoV-2 between 1 March 2020 and 31 January 2021, were included. The COVID-19 infections were split into two “waves”: wave 1 from March to August 2020 and wave 2 from September 2020 to January 2021. Cumulative incidence of COVID-19, multivariable Cox models for risk of positivity, median, and 95% credible interval of reproduction number in dialysis units were calculated separately for wave 1 and wave 2. Survival and hazard ratios for mortality were described with age- and sex-adjusted Kaplan-Meier plots and multivariable Cox proportional models. Results: 4,408 ICHD patients had COVID-19 during the study period. Unadjusted survival at 28 days was similar in both waves (wave 1 75.6% [95% confidence interval [CI]: 73.7–77.5], wave 2 76.3% [95% CI 74.3–78.2]), but death occurred more rapidly after detected infection in wave 1. Long vintage treatment and not being on the transplant waiting list were associated with higher mortality in both waves. Conclusions: Risk of death of patients on ICHD treatment with COVID-19 remained unchanged between the first and second outbreaks. This highlights that this vulnerable patient group needs to be prioritized for interventions to prevent severe COVID-19, including vaccination, and the implementation of measures to reduce the risk of transmission alone is not sufficient.

**引言**：本回顾性队列研究对比了英格兰、威尔士及北爱尔兰地区新冠疫情第一波与第二波大流行期间，中心血液透析（in-centre haemodialysis, ICHD）患者的转归情况。

**方法**：本研究纳入2019年12月31日正在接受中心血液透析、截至2020年3月1日仍存活且未接受肾移植，并在2020年3月1日至2021年1月31日期间经实时荧光定量聚合酶链反应（polymerase chain reaction, PCR）检测证实严重急性呼吸综合征冠状病毒2（SARS-CoV-2）感染的18岁及以上患者。本研究将新冠病毒感染划分为两波疫情：第一波为2020年3月至8月，第二波为2020年9月至2021年1月。分别针对两波疫情计算了新冠感染累积发病率、感染风险的多变量Cox模型、透析单元内再生数（reproduction number）的中位数及95%可信区间。采用年龄与性别校正的Kaplan-Meier生存曲线及多变量Cox比例风险模型，分析了患者的生存情况及死亡风险比（hazard ratio, HR）。

**结果**：本研究期间共有4408例中心血液透析患者发生新冠感染。两波疫情中患者的28天未校正生存率相近（第一波为75.6%，95%置信区间[CI]：73.7~77.5；第二波为76.3%，95%CI：74.3~78.2），但第一波中感染确诊后患者的死亡进程更快。在两波疫情中，透析治疗时长较长及未列入肾移植等待名单的患者死亡率均更高。

**结论**：接受中心血液透析的新冠感染患者，其死亡风险在两次疫情暴发期间未发生显著变化。本研究结果提示，需优先对这一脆弱患者群体采取干预措施以预防重症新冠，包括疫苗接种；仅通过降低传播风险的单一措施并不足够。