ABSTRACT
BACKGROUND AND AIMS AKI is the most frequent complication after respiratory failure in COVID-19. AKI increases mortality risk, length of hospital stay and healthcare costs, with possible progression towards CKD. Study aims: (1) evaluation of AKI incidence in 1020 COVID-19 hospitalized patients;(2) comparison of AKI incidence in COVID-19 versus 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. METHOD AKI incidence was calculated matching laboratory and administrative data of 26 214 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 the 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 versus 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 the AKI group;AKI is an independent risk factor for death. 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 the motor function impairment and a worse post-traumatic stress response. GFR reduction was 1.8 mL/min in non-AKI patients versus 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 the 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 nephrological and multidisciplinary follow-up of frail patients who developed AKI during hospitalization for COVID-19.Figure 1: Kaplan–Maier curves of survival for hospitalized COVID-19 patients on the basis of AKI-specific cut off of RPA.Table 1. Univariate and multivariate logistic regression analyses for AKI in hospitalized patients with COVID-19UNIVARIATE MODELMULTIVARIATE MODELOdds ratio95% CIPOdds ratio95% CIPAge, years1.000.97–1.03.9600.960.91–1.01.146Male gender0.870.32–2.33.7770.260.05–1.23.090Charlson index1.110.90–1.38.3251.160.89–1.53.266Hypertension2.791.13–6.88.0251.250.30–5.30.759Diabetes0.560.14–2.29.422Heart failure1.190.25–5.70.828Creatinine, mg/dL4.841.23–29.13.02650.74.62–556.01.001RPA < 24 HU2.220.86–5.74.1004.561.27–16.44.020