Concordance Analysis Between KDIGO Definition of Acute Kidney Injury and Its Coding in Clinical Practice

Rationale & Objective: Acute Kidney Injury (AKI) in research is typically identified using KDIGO criteria based on changes in serum creatinine (SCr) and urine output (UO), whereas in clinical practice AKI is documented through ICD-9/10 diagnosis codes at discharge.This study evaluates how KDIGO-defined AKI corresponds to clinically documented AKI and analyzes discordant cases to understand respective strengths of each method.Study Design: Retrospective cohort study.Setting & Participants: We analyzed 54,210 hospital admissions with Intensive Care Unit (ICU) stays from 43,530 patients at Beth Israel Deaconess Medical Center (BIDMC) over fifteen-years (2008-2022).Predictors: SCr and UO values recorded during a hospital admission.Outcomes: Hospital-coded AKI, defined as presence of AKI among the ICD-9/10 codes assigned at discharge. Analytical Approach:We quantified concordance between KDIGO-defined AKI and hospitalcoded AKI using Cohen's kappa () and examined patterns of disagreement.Machine learning models were trained to assess the association between SCr and hospital-coded AKI .Results: KDIGO-defined AKI had low concordance with ICD-coded AKI ( = 0.37), while a formula using maximum SCr achieved higher concordance ( = 0.61).KDIGO criteria frequently detected small SCr increases that were not coded, while coding frequently detected patients with high SCr at presentation that were missed by KDIGO.Limitations: Our analysis is confined to a single hospital system in the United States.Data used in this study lacked information about pre-admission SCr baselines.