Recognition patterns of acute kidney injury in hospitalized patients

Background and Objectives Acute Kidney Injury (AKI) during hospitalization is associated with increased complications and mortality. Despite efforts to standardize AKI management, its recognition in clinical practice is limited. Methods To assess and characterize different patterns of AKI diagnosis, we collected clinical data, serum creatinine (sCr) levels, comorbidities, and outcomes from adult patients using the Hospital Discharge Form (HDF). AKI diagnosis was based on administrative data and according to KDIGO criteria by evaluating sCr variations during hospitalization. Additionally, patients were also categorized based on the timing of AKI onset. Results Among 56 820 patients, 42 900 (75.5%) had no AKI, 1 893 (3.3%) had AKI diagnosed by sCr changes and coded in HDF (Full-AKI), 2 529 (4.4%) had AKI reported on HDF but not meeting sCr-based criteria (HDF-AKI), and 9 498 (16.7%) had undetected AKI diagnosed by sCr changes but not coded in HDF (KDIGO-AKI). Overall, AKI incidence was 24.5%, with a 68% undetection rate. Patients with KDIGO-AKI were younger, had a higher proportion of females, lower comorbidity burden, milder AKI stages, more frequent admissions to surgical wards, and lower mortality compared to Full-AKI. All AKI groups had worse outcomes than those without AKI, and AKI, even if undetected, was independently associated with mortality risk. Patients with AKI at admission had different profiles and better outcomes than those developing AKI later. Conclusions AKI recognition in hospitalized patients is highly heterogeneous, with a significant prevalence of undetection. This variability may be affected by patients ‘characteristics, AKI-related factors, diagnostic approaches, and in-hospital patient management. AKI remains a major risk factor, emphasizing the importance of ensuring proper diagnosis for all patients.