Validity of the International Classification of Diseases, Tenth Revision code for acute kidney injury in elderly patients at presentation to the emergency department and at hospital admission

Y. Joseph Hwang, Salimah Z. Shariff, Sonja Gandhi, Ron Wald, Edward Clark, Jamie L. Fleet, Amit X. Garg

Research output: Contribution to journalArticlepeer-review

Abstract

Objective: To evaluate the validity of the International Classification of Diseases, Tenth Revision (ICD-10) code N17x for acute kidney injury (AKI) in elderly patients in two settings: at presentation to the emergency department and at hospital admission. Design: A population-based retrospective validation study. Setting: Southwestern Ontario, Canada, from 2003 to 2010. Participants: Elderly patients with serum creatinine measurements at presentation to the emergency department (n=36 049) or hospital admission (n=38 566). The baseline serum creatinine measurement was a median of 102 and 39 days prior to presentation to the emergency department and hospital admission, respectively. Main outcome measures: Sensitivity, specificity and positive and negative predictive values of ICD-10 diagnostic coding algorithms for AKI using a reference standard based on changes in serum creatinine from the baseline value. Median changes in serum creatinine of patients who were code positive and code negative for AKI. Results: The sensitivity of the best-performing coding algorithm for AKI (defined as a ≥2-fold increase in serum creatinine concentration) was 37.4% (95% CI 32.1% to 43.1%) at presentation to the emergency department and 61.6% (95% CI 57.5% to 65.5%) at hospital admission. The specificity was greater than 95% in both settings. In patients who were code positive for AKI, the median (IQR) increase in serum creatinine from the baseline was 133 (62 to 288) μmol/l at presentation to the emergency department and 98 (43 to 200) μmol/l at hospital admission. In those who were code negative, the increase in serum creatinine was 2 (-8 to 14) and 6 (-4 to 20) μmol/l, respectively. Conclusions: The presence or absence of ICD-10 code N17x differentiates two groups of patients with distinct changes in serum creatinine at the time of a hospital encounter. However, the code underestimates the true incidence of AKI due to a limited sensitivity.

Original languageEnglish (US)
Article numbere001821
JournalBMJ open
Volume2
Issue number6
DOIs
StatePublished - 2012
Externally publishedYes

ASJC Scopus subject areas

  • Medicine(all)

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