Acute kidney injury in hospitalized patients with real-life analysis of incidence and clinical impact in Italian hospitals (the SIN-AKI study)

Acute Kidney Injury (AKI) is a common condition with significant impact on morbidity, mortality, and healthcare costs. This study explores the epidemiology of AKI, highlighting key factors and outcomes. In a retrospective study we evaluated patients admitted to hospital from 2016 to 2019, excluding those with pre-existing chronic kidney disease (CKD) stages 4-5. Data were extracted from hospital databases, with AKI defined by changes in serum creatinine (sCr) according to KDIGO criteria. Additionally, AKI was classified as "de novo" or as AKI on CKD in the subgroup of patients with available pre-hospital eGFR. Outcomes included mortality, hospital stay duration (LOS), AKI recovery, and persistent AKI. Of 87,087 patients, 17,946 (20.6%) developed AKI. AKI patients were older, with more comorbidities, and had significantly higher mortality (17.7% vs. 4.3%, p < 0.001). AKI was associated with in-hospital mortality (HR 1.23, 95% CI 1.16-1.30), longer LOS, and ICU admission. Mortality increased with AKI severity. Considering the 34,285 patients (39% of the total cohort) with pre-hospital eGFR, AKI occurred in 17.3% patients without previous CKD and in 31.1% of patients with previous CKD. These patients presented higher incidence of ICU admission and mortality. Additionally, 17.6% of AKI patients had persistent kidney dysfunction at discharge, often requiring extended hospitalization and ICU care. The substantial impact of AKI on both short- and potentially long-term health emphasizes the importance of early detection, personalized management, and structured follow-up to enhance outcomes and reduce CKD progression risk.