Background: The COVID-19 pandemic significantly disrupted care delivery that limited access to providers, acute and timely non-acute evaluation, and clinical intervention. Dialysis patients with kidney failure are particularly vulnerable to COVID-19 infection, COVID-19 related morbidity and mortality because they commonly have multiple chronic conditions, typically require thrice weekly life-sustaining dialysis treatment in close- quartered clinic settings, are already prone to fragmented care, and especially susceptible to disrupted care. The COVID-19 pandemic presents fundamental threats to dialysis patients, and there is an urgent need to examine the impact of disrupted care for this vulnerable and uniquely healthcare reliant population of patients. Over 16,000 of enrolled Veterans receive chronic dialysis through Veterans Health Administration (VA) Kidney Program’s VA and VA Community Care providers. VA Community Care improves access to life- sustaining dialysis services for 80% of Veterans with kidney failure with limited access to the VHA’s 70 dialysis units. In prior work, we found lower 2-year mortality among Veterans receiving dialysis exclusively in VA compared to those receiving dialysis in non-VA settings, consistent with VA and non-VA comparative studies in other clinical contexts. These differences may be due to more comprehensive integrated services (e.g., co- located primary and tertiary care services, care management, social work, national electronic medical record) in VA, compared with the more fragmented and siloed dialysis care in private sector community settings. Significance: Pandemic-related disruptions may disproportionately affect Veterans with serious conditions and social risk factors like those with kidney failure and the nature and impact of pandemic-related disruptions may differ in VA and non-VA systems. However, rigorous comparisons of COVID-related care disruptions and outcomes between Veterans receiving healthcare in VA and non-VA settings are lacking. Specific Aims: Building on our team’s research expertise, this study will: 1) Quantify the impact of COVID-19 on 1a) disrupted care for prevalent patients and 1b) deferred care for incident patients in a national cohort of Veterans with ESKD and compare the extent of these impacts between VA- financed dialysis care in VA and VA Community Care settings from 2018-2022. 2) Compare patient-level outcomes and racial and socioeconomic disparities in outcomes in VA and non-VA dialysis settings before and during the COVID pandemic time periods. Methodology: We will conduct a longitudinal cohort study of all VA-enrolled patients with end-stage kidney disease receiving VA-financed dialysis care between 2018 and 2022, to observe care patterns before the pre- COVID phase (Jan 2018-Feb 2020), the acute COVID phase defined as the first case of COVID until authorization of the vaccine (Mar 2020-Dec 2020) and the recovery phase when COVID-19 vaccination was available (Jan 202...