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Performance and limitations of administrative data in the identification of AKI.

TitlePerformance and limitations of administrative data in the identification of AKI.
Publication TypeJournal Article
Year of Publication2014
AuthorsGrams ME, Waikar SS, MacMahon B, Whelton S, Ballew SH
Secondary AuthorsCoresh JJ
JournalClin J Am Soc Nephrol
Volume9
Issue4
Pagination682-9
Date Published2014 Apr
ISSN1555-905X
KeywordsAcute Kidney Injury, Aged, Biomarkers, Clinical Coding, Creatinine, Data Mining, Databases, Factual, Electronic Health Records, Female, Hospital Mortality, Hospitalization, Humans, International Classification of Diseases, Male, Middle Aged, Predictive Value of Tests, Prognosis, Reproducibility of Results, Severity of Illness Index, Time Factors, United States, Urination
Abstract

BACKGROUND AND OBJECTIVES: Billing codes are frequently used to identify AKI events in epidemiologic research. The goals of this study were to validate billing code-identified AKI against the current AKI consensus definition and to ascertain whether sensitivity and specificity vary by patient characteristic or over time.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: The study population included 10,056 Atherosclerosis Risk in Communities study participants hospitalized between 1996 and 2008. Billing code-identified AKI was compared with the 2012 Kidney Disease Improving Global Outcomes (KDIGO) creatinine-based criteria (AKIcr) and an approximation of the 2012 KDIGO creatinine- and urine output-based criteria (AKIcr_uop) in a subset with available outpatient data. Sensitivity and specificity of billing code-identified AKI were evaluated over time and according to patient age, race, sex, diabetes status, and CKD status in 546 charts selected for review, with estimates adjusted for sampling technique.

RESULTS: A total of 34,179 hospitalizations were identified; 1353 had a billing code for AKI. The sensitivity of billing code-identified AKI was 17.2% (95% confidence interval [95% CI], 13.2% to 21.2%) compared with AKIcr (n=1970 hospitalizations) and 11.7% (95% CI, 8.8% to 14.5%) compared with AKIcr_uop (n=1839 hospitalizations). Specificity was >98% in both cases. Sensitivity was significantly higher in the more recent time period (2002-2008) and among participants aged 65 years and older. Billing code-identified AKI captured a more severe spectrum of disease than did AKIcr and AKIcr_uop, with a larger proportion of patients with stage 3 AKI (34.9%, 19.7%, and 11.5%, respectively) and higher in-hospital mortality (41.2%, 18.7%, and 12.8%, respectively).

CONCLUSIONS: The use of billing codes to identify AKI has low sensitivity compared with the current KDIGO consensus definition, especially when the urine output criterion is included, and results in the identification of a more severe phenotype. Epidemiologic studies using billing codes may benefit from a high specificity, but the variation in sensitivity may result in bias, particularly when trends over time are the outcome of interest.

DOI10.2215/CJN.07650713
Alternate JournalClin J Am Soc Nephrol
PubMed ID24458075
PubMed Central IDPMC3974361
Grant ListHHSN268201100012C / HL / NHLBI NIH HHS / United States
HHSN268201100009I / HL / NHLBI NIH HHS / United States
HHSN268201100010C / HL / NHLBI NIH HHS / United States
R01 DK093574 / DK / NIDDK NIH HHS / United States
HHSN268201100008C / HL / NHLBI NIH HHS / United States
HHSN268201100005G / HL / NHLBI NIH HHS / United States
HHSN268201100008I / HL / NHLBI NIH HHS / United States
HHSN268201100005C / / PHS HHS / United States
HHSN268201100007C / HL / NHLBI NIH HHS / United States
HHSN268201100009C / / PHS HHS / United States
HHSN268201100011I / HL / NHLBI NIH HHS / United States
HHSN268201100011C / HL / NHLBI NIH HHS / United States
K08DK092287 / DK / NIDDK NIH HHS / United States
HHSN268201100010C / / PHS HHS / United States
HHSN268201100006C / HL / NHLBI NIH HHS / United States
HHSN268201100008C / / PHS HHS / United States
HHSN268201100012C / / PHS HHS / United States
HHSN268201100005I / HL / NHLBI NIH HHS / United States
R01 DK076770 / DK / NIDDK NIH HHS / United States
HHSN268201100007C / / PHS HHS / United States
HHSN268201100009C / HL / NHLBI NIH HHS / United States
HHSN268201100011C / / PHS HHS / United States
HHSN268201100005C / HL / NHLBI NIH HHS / United States
HHSN268201100007I / HL / NHLBI NIH HHS / United States
K08 DK092287 / DK / NIDDK NIH HHS / United States
HHSN268201100006C / / PHS HHS / United States