Association between continuous renal replacement therapy and 28-day mortality of critically ill patients with COVID-19 receiving mechanical ventilation

Background: Continuous renal replacement therapy (CRRT) has become an important multiple organ support therapy and it is widely used in the intensive care unit (ICU). The aim of this study was to clarify the association between CRRT and 28-day mortality in critically ill coronavirus disease 2019 (COVID-19) patients receiving mechanical ventilation. Materials and methods: 112 respiratory decompensated critically ill adult patients with COVID-19 admitted to a COVID-19-designated ICU were included in this retrospective cohort study. Data on demographic information, comorbidities, laboratory findings upon ICU admission, and clinical outcomes were collected. The Kaplan-Meier method and Cox proportional hazard model were applied to determine the potential risk factors associated with 28-day mortality. Results: The median age was 65.7 years, 67.8% were males, and 58.9% patients had at least one comorbidity. The median scores of the Charlson Comorbidity Index and Sequential Organ Failure Assessment (SOFA) were 3 and 7, respectively. Acute kidney injury (AKI) occurred in 57 critically ill patients upon ICU admission; 43 patients were classified as stage 2 - 3 AKI, and 36 patients were treated with CRRT. Age > 65 years, high SOFA score, damaged cardiac function, poor nutrition, and severe infection were significantly associated with increased 28-day mortality. AKI patients receiving CRRT had lower 28-day mortality compared with those not receiving CRRT (HR = 0.35, 95% CI: 0.21 - 0.58, p < 0.001). Initiating CRRT within 72 hours after mechanical ventilation did not improve survival after CRRT initiation. Conclusion: AKI prevalence and 28-day mortality are high in critically ill patients with COVID-19 receiving mechanical ventilation. CRRT plays a part in decreasing the mortality of critically ill COVID-19 patients with AKI receiving mechanical ventilation.