ICD-Coded Versus Undiagnosed Acute Kidney Injury in the Atherosclerosis Risk in Communities (ARIC) Study
In brief
ICD codes miss nearly half of creatinine-defined acute kidney injuries
In 5,692 adults, ICD codes identified only 51.4% of acute kidney injury cases defined by changes in blood creatinine, though they were more likely to detect severe cases. Undiagnosed injury was more common in women and, like coded injury, was associated with heart disease, heart failure, stroke, and death, underscoring the need to improve recognition.
- Journal
- Kidney medicine (Q1)
- Published
- 10 August 2026
- Study design
- Prospective / inception cohort
- Evidence level
- Level 2, Moderate (CEBM 2b)
- Authors
- Grace G von Oiste, Aditya Surapaneni, Carina M Flaherty, Insa M Schmidt, Kunihiro Matsushita, Josef Coresh, et al.
- PMID
- 42893195
- DOI
- 10.1016/j.xkme.2026.101492
Why clinicians should know about it
- Picked for Internal Medicine (paper of the day, 20 October 2026): Undiagnosed AKI common, prognostic significance in older adults
Abstract
RATIONALE & OBJECTIVE: Acute kidney injury (AKI) is common among older adults and associated with adverse outcomes, yet it often goes undiagnosed. We aimed to compare the prevalence of undiagnosed versus International Classification of Diseases (ICD)-coded AKI as well as their clinical and molecular characteristics and evaluate their associations with clinical outcomes. STUDY DESIGN: Prospective cohort study. SETTING & PARTICIPANTS: A total of 5,692 adults with proteomic and metabolomic profiling from the Atherosclerosis Risk in Communities study, excluding individuals with end-stage kidney disease at baseline (2011-2013). EXPOSURES: AKI, defined as either ICD-coded or undiagnosed based on 3 abstracted levels of serum creatinine measured during hospitalizations. OUTCOMES: Incident coronary heart disease, heart failure, stroke, and all-cause mortality. ANALYTICAL APPROACH: ICD-coded AKI was compared with undiagnosed AKI across all hospitalizations. Risk factors for ICD-coded and undiagnosed AKI were assessed separately using Cox proportional hazards models from study visit to the first AKI encounter. Time-varying Cox models were used to evaluate the associations of ICD-coded and undiagnosed AKI with adverse outcomes. RESULTS: ICD codes identified 51.4% of AKI defined based on changes in serum creatinine, with higher sensitivity for more severe stages and a specificity of 87.0%. Undiagnosed AKI was more common in women; otherwise, clinical risk factors for undiagnosed AKI were similar to those for ICD-coded AKI, as were proteomic and metabolomic risk factors. Both AKI groups were strongly associated with coronary heart disease, heart failure, stroke, and mortality. LIMITATIONS: AKI was estimated using 3 values of serum creatinine only and not urinary output. Diagnosed AKI was identified using billing codes, which may underestimate clinical diagnosis of AKI. CONCLUSIONS: Undiagnosed AKI is prevalent, especially among women, and is biologically and prognostically similar to ICD-coded AKI, motivating efforts to improve AKI recognition and diagnosis.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.