Epidemiology and Outcomes of Acute Kidney Diseases: A Comparative Analysis

Introduction: Acute kidney diseases and disorders (AKD) encompass acute kidney injury (AKI) and subacute or persistent alterations in kidney function that occur after an initiating event. Unlike AKI, accurate estimates of the incidence and prognosis of AKD are not available and its clinical significance is uncertain. Methods: We studied the epidemiology and long-term outcome of AKD (as defined by the KDIGO criteria), with or without AKI, in a retrospective cohort of adults hospitalized at a single centre for >24 h between 2012 and 2016 who had a baseline eGFR ≥60 mL/min/1.73 m2 and were alive at 30 days. In patients for whom follow-up data were available, the risks of major adverse kidney events (MAKEs), CKD, kidney failure, and death were examined by Cox and competing risk regression analyses. Results: Among 62,977 patients, 906 (1%) had AKD with AKI and 485 (1%) had AKD without AKI. Follow-up data were available for 36,118 patients. In this cohort, compared to no kidney disease, AKD with AKI was associated with a higher risk of MAKEs (40.25 per 100 person-years; hazard ratio [HR] 2.51, 95% confidence interval [CI] 2.16–2.91), CKD (27.84 per 100 person-years); subhazard ratio [SHR] 3.18, 95% CI 2.60–3.89), kidney failure (0.56 per 100 person-years; SHR 24.84, 95% CI 5.93–104.03), and death (14.86 per 100 person-years; HR 1.52, 95% CI 1.20–1.92). Patients who had AKD without AKI also had a higher risk of MAKEs (36.21 per 100 person-years; HR 2.26, 95% CI 1.89–2.70), CKD (22.94 per 100 person-years; SHR 2.69, 95% CI 2.11–3.43), kidney failure (0.28 per 100 person-years; SHR 12.63, 95% CI 1.48–107.64), and death (14.86 per 100 person-years; HR 1.57, 95% CI 1.19–2.07). MAKEs after AKD were driven by CKD, especially in the first 3 months. Conclusions: These findings establish the burden and poor prognosis of AKD and support prioritisation of clinical initiatives and research strategies to mitigate such risk.