Administrative data misclassifies and fails to identify nephrotoxin-associated acute kidney injury in hospitalized children.

OBJECTIVES: Nephrotoxin exposure is a common cause of acute kidney injury (AKI) in hospitalized children. AKI detection relies on regular serum creatinine (SCr) screening among exposed patients. We sought to determine how well administrative data identify hospitalized noncritically ill children with nephrotoxic medication-associated AKI in the contexts of incomplete and complete screening.
METHODS: We conducted a single-center retrospective cohort study among noncritically ill hospitalized children. We compared administrative data sensitivity to that among a separate cohort for whom adequate screening was defined as daily SCr measurement. For the original cohort, nephrotoxin exposure was defined as exposure to ≥3 nephrotoxins at once or ≥3 days of aminoglycoside therapy. AKI was defined by the change in SCr (pediatric-modified Risk Injury Failure Loss End-Stage Renal Disease [pRIFLE] criteria) or discharge code. Adequate SCr screening was defined as 2 measurements obtained ≤96 hours apart. Administrative data and laboratory values were merged to compare AKI by discharge code and pRIFLE criteria.
RESULTS: 747 of 1472 (50.7%) nephrotoxin-exposed patients were adequately screened; 82 (11.0%) had AKI by pRIFLE criteria, 52 (7.0%) by discharge code. Sensitivity of nephrotoxin-associated AKI diagnosis by discharge code compared with pRIFLE criteria was 23.2% (95% confidence interval = 14.0-32.3). In the comparison cohort, 70 (26.8%) patients had AKI by pRIFLE criteria and 26 (10.0%) by discharge code; sensitivity was 21.4% (95% confidence interval = 11.8%-31.0%).
CONCLUSIONS: pRIFLE criteria identified more patients than were identified by discharge code. Identifying patients with nephrotoxin-associated AKI by discharge code, even in the presence of complete AKI detection, underrepresents the true incidence of nephrotoxin-associated AKI in hospitalized children.