Critical Illness and Systemic Inflammation Are Key Risk Factors of Severe Acute Kidney Injury in Patients With COVID-19

INTRODUCTION

Acute kidney injury (AKI) is an important complication in COVID-19, but its precise etiology has not fully been elucidated. Insights into AKI mechanisms may be provided by analyzing the temporal associations of clinical parameters reflecting disease processes and AKI development.

METHODS

We performed an observational cohort study of 223 consecutive COVID-19 patients treated at 3 sites of a tertiary care referral center to describe the evolvement of severe AKI (Kidney Disease: Improving Global Outcomes stage 3) and identify conditions promoting its development. Descriptive statistics and explanatory multivariable Cox regression modeling with clinical parameters as time-varying covariates were used to identify risk factors of severe AKI.

RESULTS

Severe AKI developed in 70 of 223 patients (31%) with COVID-19, of which 95.7% required kidney replacement therapy. Patients with severe AKI were older, predominantly male, had more comorbidities, and displayed excess mortality. Severe AKI occurred exclusively in intensive care unit patients, and 97.3% of the patients developing severe AKI had respiratory failure. Mechanical ventilation, vasopressor therapy, and inflammatory markers (serum procalcitonin levels and leucocyte count) were independent time-varying risk factors of severe AKI. Increasing inflammatory markers displayed a close temporal association with the development of severe AKI. Sensitivity analysis on risk factors of AKI stage 2 and 3 combined confirmed these findings.

CONCLUSION

Severe AKI in COVID-19 was tightly coupled with critical illness and systemic inflammation and was not observed in milder disease courses. These findings suggest that traditional systemic AKI mechanisms rather than kidney-specific processes contribute to severe AKI in COVID-19.

[COVID-19 and acute kidney injury in the intensive care unit]

Acute kidney injury (AKI) is a frequent and severe complication in coronavirus disease 2019 (COVID-19) patients in the intensive care unit. The development of COVID-19 associated AKI is closely linked to the severity of the disease course. The main risk factor for kidney failure requiring kidney replacement therapy is the necessity for invasive ventilation, whereby the onset of renal failure is often closely associated with the timing of intubation. Additionally, the risk factors for a severe course of COVID-19 have been shown to also be risk factors for renal failure. AKI in COVID-19 shows a high mortality and in some patients leads to chronic kidney disease; however, full recovery of kidney function in survivors who need dialysis is not uncommon. With respect to prevention and treatment of renal failure associated with COVID-19, the same recommendations as for AKI from other causes are valid (Kidney Disease: Improving Global Outcomes, KDIGO bundles). Due to the large numbers of patients in the setting of overwhelmed resources, the availability of extracorporeal renal replacement procedures can become critical, especially since hypercoagulation is frequent in COVID‑19. In order to avoid triage situations, in some centers acute peritoneal dialysis was used as an alternative to extracorporeal procedures.