The Incidence and Outcomes of Renal Replacement Therapy in Patients with Severe COVID-19 Infection Requiring Mechanical Ventilation

Rationale: Acute Kidney Injury (AKI) is common in critically ill patients. Patients in the intensive care unit (ICU) who develop AKI and multi organ failure face a high mortality rate and in those progressing to renal replacement therapy (RRT) mortality rates may exceed 50%. Coronavirus disease 2019 (COVID-19) is a global pandemic caused by severe acute respiratory distress syndrome coronavirus 2 (SARS-CoV-2). Severe COVID-19 often results in multi system involvement and may particularly affect the kidneys. The incidence of AKI in this setting is unclear and has varied widely in reports based on population evaluated. There is limited data on the incidence and outcomes of severe AKI necessitating RRT in COVID-19 patients who progress to respiratory failure requiring mechanical ventilation (MV). We conducted a retrospective study in order to determine the incidence and outcomes associated with need for RRT in patients with COVID-19 that progressed to need MV. Methods: We reviewed the records of all COVID-19 patients who were intubated for respiratory failure in our hospital between March and May 2020. Our primary endpoint was the incidence of RRT while outcomes in these subjects (e.g. hospital mortality, length of stay and recovery of renal function) served as secondary endpoints. We examined the relationship between our endpoints and baseline demographics, pre-existing co-morbidities, severity of illness identified by vasopressor requirement, PaO2/FiO2 ratio, plateau pressure, fluid balance in the first three days, and treatment with full strength anticoagulation and/or tocilizumab. Results: Our final cohort consisted of 135 patients of which 46 (34.0%) required RRT. Patients who required RRT had similar baseline characteristics to those who did not. Patients treated with RRT had a higher fluid balance in the first 72 hours (+4761 vs +3076, p=0.040). The mortality rate was higher in those requiring RRT (69.6% vs 39.3%, p=0.001), while the median ICU and hospital stay was lower in this subgroup. Amongst hospital survivors evaluated by the end of our study, 43.0% continued to require RRT, 7.0% no longer required RRT but still had some degree of renal dysfunction, and 50.0% had complete recovery of renal function. Conclusion: There is high incidence of AKI in patients with COVID-19 who require MV and one third of these patients develop renal failure requiring RRT. The mortality in these patients is high and exceeds that reported in patients with Acute Respiratory Distress Syndrome from other causes who need RRT. Complete renal function recovery often occurs in survivors.