Outcomes of acute kidney injury depend on initial clinical features: a national French cohort study.

Background: Acute kidney injury (AKI) is a common condition that is associated with poor short- and long-term outcomes. The aim of this nationwide cohort study was to profile the long-term outcome of patients admitted for AKI in France.

Methods: Based on the comprehensive French hospital discharge database, all hospitalizations for an AKI episode were categorized in four groups according to the presence of at least one dialysis session [renal replacement therapy (RRT)] and according to the coding of AKI as the principal or associated diagnosis (PRINC_DIAG or ASS_DIAG).

Results: In this nationwide cohort of 989 974 patients (median age 77 years) hospitalized with AKI during the 2009-16 period, 422 739 (43%) patients died (235 572 during the first hospitalization) and 40 015 (4%) patients reached end-stage renal disease (ESRD) (5962 during first hospitalization) up to 31 December 2016. Patients without RRT and discharged from hospital had a cumulative incidence of ESRD that ranged from 5.3% (5.2-5.4) in the ASS_DIAG group to 28.7% (27.9-29.5) in the RRT-PRINC_DIAG group at 60 months. The cumulative incidence of death ranged from 31.0% (30.2-32.2) in the RRT-ASS_DIAG group to 45.5% (45.3-45.7) in the ASS_DIAG group. Initial clinical features were associated with outcome independent of comorbidities and age.

Conclusions: The death penalty of AKI is abysmal and AKI was an important predisposing factor to chronic ESRD. Our study strengthens the current recommendations for long-term follow-up of patients with AKI. The novelty of this study is to propose a clinical classification of AKI episodes that is easy to detect in administrative medical databases and that is strongly associated with immediate and long-term outcomes.