ABSTRACT
BACKGROUND AND AIMS Acute kidney injury (AKI) is a common complication among patients hospitalized with COVID-19. The incidence of AKI is estimated to be around 5%–80%, according to the series, but data on renal function evolution is limited. Our main objective was to describe the incidence of AKI in patients with SARS-CoV-2 infection;secondarily, we analysed the severity of AKI and medium-term renal function evolution in these patients. METHOD A retrospective observational study that included patients hospitalized a single hospital, diagnosed with SARS-CoV-2 infection, who developed AKI (March-May 2020). We register clinical and demographic characteristics, creatinine upon admission and prior to discharge, as well as creatinine and CKD-EPI glomerular filtration rate (eGFR) after at least 3 months after discharge. CKD was defined according to KDIGO stages based on the eGFR (G3-G5). The KDIGO classification was used to define and classify AKI. Recovery of kidney function was defined as difference in at discharge or post-hospitalization creatinine < 0.3 mg/dL with respect basal creatinine. The clinical follow-up ranged from admission to death or end of study. RESULTS Of 258 patients hospitalized with SARS-CoV-2 infection, AKI occurred in 73 (28.3%). 63% (n = 46) were men;the mean of age was 69 years (57–76). DRA severity: 35 (48%) KDIGO-1, 15 (21%) KDIGO-2 and 23 (31%) KDIGO-3. The mean stay was associated with the severity of AKI: 7 days (3–11) for KDIGO-1, 11 days for KDIGO-2 (5–22) and 12 days (8–35) for KDIGO-3 (P = .02). The stage of CKD established differences in the severity of AKI: 66.6% (n = 6) of the patients with CKD G4–G5 presented AKI-KDIGO 3 versus only 25.0% (n = 4) in the CKD-G3 patients (P = .02). Admission to the ICU was more frequent in KDIGO 2–3 versus KDIGO-1 [39% (n = 15) versus 9% (n = 3);P < .01]. Of the 48 patients discharged, 30 (62.5%) had recovered their baseline renal function upon discharge. Only 2 are still on RRT after 8 months (2.7% of all patients). Of the 25 patients died (34% of patients with AKI) with a median time of 3 days from DRA diagnosis (1–8). Renal function of 35 patients was monitored, which correspond to 19 (54%) KDIGO-1, 8 (23%) KDIGO-2, 8 (23%) KDIGO-3 stages. In these patients, analytical control starting 3 months after hospitalization revealed FG 66 (SD 30;56–76) mL/min/1.73 m2. We have not found differences in renal function between pre- and post-hospitalization in related test. A total of 77% (n = 37) of discharged patients recovered their baseline renal function in the post-hospitalization control. CONCLUSION The incidence of AKI in the context of COVID-19 in our series was 28.3%, with an associated mortality of 34.2%. Most of the patients presented with AKI KDIGO 1 (47.9%). The severity of AKI is associated with a longer hospital stay, admission to the ICU and the requirement for RRT. The advanced stages of CKD pre-admission showed more severity of AKI. The maintenance in TRS in our series has been 2.7%. Patients who were discharged for recovery/improvement of COVID-19 had normalized kidney function during subsequent follow-up, regardless of the severity of the AKI developed on admission for COVID-19.