Study Identifies Inpatient Conditions Associated with Increased Risk for Recurrent Acute Kidney Injury among Veterans

BACKGROUND:
The increasing incidence of acute kidney injury (AKI) highlights a growing need to develop strategies to reduce the poor outcomes among AKI survivors. Up to one-third of elderly patients hospitalized with AKI are re-hospitalized with recurrent AKI within 12 months, and each episode of recurrence is associated with an increased risk for progression to advanced chronic kidney disease. A first step in preventing recurrent AKI is to identify patients at highest risk. This study sought to identify clinical risk factors for recurrent AKI – present during the index hospitalization for AKI – among 11,683 Veterans who were hospitalized for at least 24 hours between January 2003 and December 2010 at one of five VAMCs located in Tennessee, Kentucky, and West Virginia. The primary outcome was hospitalization complicated by recurrent AKI within 12 months of discharge from the index AKI event. Using VA data, investigators also assessed patient demographics, inpatient and outpatient procedures and diagnoses, lab data, computerized physician order entry, and comorbidities.

FINDINGS:

• In addition to known demographic and comorbid risk factors for AKI (i.e., older age, diabetes, dementia), Veterans at highest risk for hospitalization with recurrent AKI were those whose index AKI hospitalization included congestive heart failure as a primary diagnosis, decompensated advanced liver disease, cancer with or without chemotherapy, acute coronary syndrome, and intravascular volume depletion.
• Of the Veterans in this cohort, 49% were hospitalized at least once during the follow-up period, and 25% were hospitalized with recurrent AKI within 12 months of discharge. Median time to recurrent AKI was 64 days.
• The one-year mortality from time of discharge was 23%, and approximately 40% of Veterans who died were re-hospitalized with recurrent AKI before death.

LIMITATIONS:

• The detection of recurrent AKI was limited to Veterans hospitalized with AKI, which may underestimate the actual number of episodes.
• Investigators did not examine multiple AKI episodes that may have occurred during the index hospitalization, as the pathophysiology likely differs, but this is an area where further study is needed.
• Investigators cannot be sure that ascertainment bias in measuring outpatient serum creatinine measurement did not contribute to the diagnosis of recurrent AKI in some Veterans.

IMPLICATIONS:

• These findings can help facilitate risk stratification, guide appropriate referral following AKI, and help generate potential risk-reduction strategies.

AUTHOR/FUNDING INFORMATION: This study was partly funded by HSR&D (IIR 11-292, IIR 13-073, and CDA 08-020). Dr. Matheny was supported by an HSR&D Career Development Award and is part of the Geriatric Research Education and Clinical Care Center at the Tennessee Valley Health System, Nashville, TN.

Siew E, Parr S, Abdel-Kader K, Eden S, Peterson J, Bansal N, Hung A, Fly J, Speroff T, Ikizler T, and Matheny M. Predictors of Recurrent Acute Kidney Injury. Journal of the American Society of Nephrology. August 11, 2015;e-pub ahead of print.