Acute Kidney Injury Often Unnoticed Among Inpatients

Lara C. Pullen, PhD

June 01, 2017

Only one third of patients who develop hospital-acquired acute kidney injury (HA-AKI) have medical records that include the diagnostic code for AKI, a new study showed. The omission means hospitals likely underestimate the significance of HA-AKI in their facility.

In addition, Anne-Sophie Jannot, MD, PhD, a specialist in public health at the Paris Descartes University in France, and colleagues found that the risk for HA-AKI was particularly high among patients with sepsis, heart disease, polytrauma, liver disease, and cardiovascular surgery. They report their results in an article published online May 8 in the Clinical Journal of the American Society of Nephrology.

In the study, the researchers employed an approach initially developed to identify connections between genetic loci and phenotypic traits. However, in this setting, the team used the technique to examine, in an unbiased way, which diagnoses may predispose a patient to HA-AKI.

Along with the unbiased approach for identifying predisposing diagnoses, the team also chose to use laboratory data from electronic medical records (EMRs) to identify HA-AKI, instead of relying on the presence of International Classification of Diseases, Tenth Revision (ICD-10), codes. They defined patients with HA-AKI as those who had a 1.5-fold or greater increase in plasma creatinine level between a baseline measurement (drawn within 24 hours of admission) and a second test taken within 7 days of admission. This definition is similar to that used in the Acute Kidney Injury Network classification.

They evaluated the records of 126,736 unique individuals who were admitted to their tertiary academic hospital between 2006 and 2013. Of these, 8% had HA-AKI based on plasma creatinine. However, just 30% of the EMRs for those patients had an ICD code for AKI.

The likelihood of ICD-10 coding appeared to depend on the Acute Kidney Injury Network class, such that patients with Acute Kidney Injury Network stage 1 disease were less likely to have an ICD code than those with more severe disease.

Patients at Risk

When the researchers looked to see whether any diagnoses were more closely associated with HA-AKI, they identified five clusters of diagnoses.

The first cluster, which included 66% of patients with HA-AKI, as defined by creatinine levels, was characterized by "a severe septic shock situation complicated with hemodynamic instability and organ failure."

The second cluster, which included 44% of the patients, was characterized by heart disease. The third cluster (19%) was defined by severe polytrauma complicated with hemodynamic instability and rhabdomyolysis. The fourth cluster (10%) corresponded to severe liver disease that may be associated with portal hypertension and/or the hepatorenal syndrome. The fifth cluster (6%) included patients who had just undergone cardiovascular surgery.

The researchers' EMR-based exploration allowed them to efficiently discover the prevalence of disease in a real-life setting. They caution, however, that their analysis was performed using data from only a single French urban tertiary hospital and may not reflect the situation in hospitals with different diagnosis and billing procedures and/or different EMR software.

Overall, approximately 20% of the diagnoses associated with HA-AKI corresponded to kidney diseases such as tubulointerstitial nephritis, necrotizing vasculitis, or myeloma cast nephropathy.

"We provide a proof of concept of the applicability of large-scale diagnosis-wide analyses without prior hypotheses in addressing important issues related to renal diseases and we demonstrate how these diseases may be associated with complex medical situations," the authors write. "Using this method, we obtained a description of all the medical situations associated with HA-AKI, as defined using validated criteria, at a high level of comprehensiveness. Conducted without an a priori hypothesis, this systematic search for associations yielded a definitive picture of the phenotypes of HA-AKI."

The Source of the Problem?

AKI arises if the kidneys are deprived of normal blood flow. AKI can be serious, and physicians diagnose it when there is an abrupt decline in kidney function. The fact that an HA-AKI diagnosis was often not included in the patient's medical record suggests either that AKI was not identified and diagnosed by a physician in the hospital or that the physician considered an AKI diagnosis to be a minor medical issue not relevant enough to be encoded.

"Our findings highlight the frequency and the severity of the medical situations associated with hospital-acquired AKI," said coauthor Nicolas Pallet, MD, PhD, a nephrologist at Paris Descartes University, in a press release. "Our results also support the urgent need for efforts to ensure more accurate identification of hospital-acquired AKI."

The authors have disclosed no relevant financial relationships.

CJASN. Published online May 8, 2017. Abstract

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