Acute Kidney Injury Is Associated With Increased In-Hospital Mortality And With Impairment Of Kidney, Lung, Motor and Immune Function 1 Year After Discharge for COVID-19

ABSTRACT

Background and aims: Acute Kidney Injury (AKI) is the most frequent complication after respiratory failure in COVID-19 patients. AKI increases mortality risk, length of hospital stay and healthcare costs with possibile progression toward CKD. Study aims: 1) evaluation of AKI incidence in 1020 COVID-19 hospitalized patients;2) comparison of AKI incidence in COVID-19 vs. pre-pandemic period;3) establishment of out-patient follow-up for monitoring kidney, lung, motor and immune function;4) creation of a biobank for biomarker discovery studies. Methods: AKI incidence was calculated matching laboratory and administrative data of 26214 hospitalized patients in 2018-2019 and in 1020 COVID-19 patients in 2020-2021 KDIGO algorithms were applied for AKI grading. After 12 months from discharge, 232 COVID AKI patients and relative controls matched for age and gender were evaluated for kidney (eGFR, biomarkers of tubular damage NGAL, CCl-14, DKK-3), lung (DLCO, CT scan) and neuro-motor (SPPB, 2-min walking test, post-traumatic stress test-IES) function. Results: Before pandemic, in-hospital AKI incidence was 18% (10% KDIGO 1, 5% KDIGO 2, 3% KDIGO 3) median age of AKI patients was 69. In-hospital mortality was 3.5 % in non-AKI group vs. 15% in AKI group in accordance with KDIGO stages. In COVID patients, AKI incidence increased to 37% (20% KDIGO 1,11% KDIGO 2, 6% KDIGO 3) median age of patients was 54. In-hospital mortality was 31 % in AKI group. After 12 months from hospital discharge, COVID AKI patients showed a persistent reduction of respiratory function (severe DLCO impairment <60%) related to the extent of CT scan abnormalities. AKI patients also presented motor function impairment and a worse posttraumatic stress response. GFR reduction was 1.8 ml/min in non AKI vs. 9.7 ml/min in AKI COVID patients not related to age. Urinary DKK-3 and CCL-14 were also higher in the AKI group. Last, IgG response after SARS-CoV-2 vaccination was significantly lower in the AKI group. Conclusion: AKI incidence was significantly increased during COVID-19 in respect to pre-pandemic period with an association with higher mortality in class 2-3 KDIGO. In the post-COVID follow-up, AKI was associated with lung and neuro-motor function impairment, a defective antibody response and a sudden GFR decline concomitant to the persistence of tubular injury biomarkers. These results suggest the importance of a nephrological and multidisciplinary follow-up of frail patients who developed AKI during hospitalization for COVID-19.