INTRODUCTION: Acute kidney injury (AKI) is frequently associated with severe COVID-19 infection. However, it is also frequently observed in patients with ARDS of other etiologies. We wanted to compare the incidence and outcomes of AKI in patients with COVID-19 ARDS compared to patients with ARDS of other etiologies.
METHOD: We conducted a retrospective observational study including adult (≥18 years old) patients admitted to the intensive care unit of a tertiary Swiss hospital between January 2010 and May 2020. We identified all patients with ARDS as either primary or secondary diagnosis. Patients were separated according to whether ARDS was associated with a COVID-19 infection (COVID group) or not (NO COVID group). We extracted baseline characteristics, demographic parameters and outcomes from electronic medical records. We performed univariate analyses to compare these parameters between patients in the COVID and NO COVID groups. In addition, we compared, the characteristics of patients who developed severe (KDIGO Stage 2 or 3) AKI (severe AKI group) to those who did not (non-severe AKI group).
RESULTS: Among the 507 patients included in this study, (348 men [68.6%] with a median age of 62 [IQR, 22] and a median Simplified Acute Physiology Score II score of 51 [IQR, 25]), 79 (15.6%) were COVID-19 positive (COVID group) while 428 (84.4%) were not (NO COVID group).
Compared to those in the NO COVID group, patients in the COVID group had less overall comorbidities (median Charlson score 3.0 [IQR, 3.0] vs 4.0 [4.0], p<0.001), but more hypertension (57.0% vs 39.5%, p<0.001). Similarly, they were less likely to have a surgical admission (p<0.001) but more likely to have been admitted through the emergency room (p<0.01).
Patients in the COVID-19 group had a similar incidence of AKI during the hospital stay compared to patients in the NO COVID group (100% vs 95.3%, p=0.39). Among the COVID group, 69 (87.3%) had severe AKI versus 359 (83.9%) in the NO COVID group. When only serum creatinine criteria was considered, 36 (45.6%) had severe AKI in the COVID group versus 280 (65.4%) in the NO COVID group.
In our cohort, 428 (84.4%) patients developed severe AKI and 79 (15.6%) did not. Compared to patients in the non-severe AKI group, those in the severe AKI group had a similar comorbidity profile except for a higher BMI (p<0.001). The proportion of patients with COVID-19 was similar in both groups (69 [16.1%] vs 10 [12.7%], p=0.44).
CONCLUSIONS: AKI is very common in critically ill patients with ARDS. Compared to other ARDS etiologies, COVID-19 does not appear to be associated with a higher incidence of AKI and severe AKI.