RECOVID: Retrospective Observational Study of Renal Outcomes and Long-Term Mortality in Patients With COVID-19-Associated AKI, A Comparison Between Vaccinated and Unvaccinated Patients.

Rationale & Objective: Acute kidney injury (AKI) is a common complication in patients with Coronavirus disease-2019 (COVID-19) infections, with rates as high as 32% to 46%, and it has been associated with poor outcomes. However, the long-term renal and survival outcomes among hospitalized patients with COVID-19 and AKI are not fully understood.

Study Design: A single-center cohort study.

Setting & Participants: Total of 972 adult patients admitted with COVID-19 infection and AKI at a single large urban academic medical center from March 1, 2022, to March 30, 2022. Among these, 411 (42.3%) did not receive a dose of a US FDA-approved COVID-19 vaccine, and 467 (48.0%) had completed the primary vaccine series.

Exposure: Patients admitted with COVID-19 infection and AKI were analyzed using vaccination status as the exposure. Additional exposures included demographics, comorbid conditions, and need for continuous renal replacement therapy (CRRT) during hospitalization.

Outcome: The primary outcome was in-hospital mortality. Secondary outcomes included long-term mortality, length of hospital stay, and the need for renal replacement therapy (RRT) at discharge.

Analytical Approach: The vaccinated and unvaccinated cohorts were characterized using descriptive analyses. The cohorts were analyzed using the Kaplan-Meier method and groups were compared using the log-rank test. Multivariable cox, logistic, and linear regression models were used for mortality, RRT status at discharge, and length of stay, respectively.

Results: Among 3,527 hospitalized patients with a COVID-19 infection, AKI occurred in 972 patients. Of the 972 patients with AKI, 411 (42.3%) did not receive a dose of a US FDA-approved COVID-19 vaccine and 467 (48.0%) had completed the primary vaccine series. Unvaccinated patients had a higher rate of requiring CRRT during their hospitalization compared with vaccinated patients (15.8% vs 10.9%,  = 0.03). The CRRT during hospitalization was significantly associated with in-hospital death (adjusted HR 2.82; 95% CI, 1.88-4.25) and long-term follow-up death (adjusted HR 2.44; 95% CI, 1.73-3.42). Unvaccinated patients also had a 2.56 (95% CI, 1.52-4.30) times higher odds of being discharged on RRT when compared with those who were vaccinated. In an adjusted multivariable analysis, those who were unvaccinated had both significantly increased in-hospital mortality (adjusted HR 5.54; 95% CI, 3.36-9.13) and long-term follow-up mortality (adjusted HR 4.78; 95% CI, 3.39-6.73) when compared with those who were vaccinated.

Limitations: There was a lack of data on the ventilation status and other indicators of infection severity in patients in intensive care unit who received CRRT. In addition, data on booster COVID-19 vaccinations were lacking.

Conclusions: Vaccinated patients with a COVID-19 infection and AKI had an increase overall survival and were less likely to remain on RRT at the time of discharge. Further studies evaluating the underlying etiologies of AKI and renal outcomes among patients admitted with COVID-19 infection in both vaccinated and unvaccinated patients is important in the development of targeted therapies and guidance on management and follow-up approaches to monitor renal recovery and model outcomes for providing chronic kidney disease care for these patients.