Acute Kidney Injury Recovery Pattern and Subsequent Risk of CKD: An Analysis of Veterans Health Administration Data

Abstract

Background: Studies suggest an association between acute kidney injury (AKI) and long-term risk for chronic kidney disease (CKD), even following apparent renal recovery. Whether the pattern of renal recovery predicts kidney risk following AKI is unknown.

Study design: Retrospective cohort.

Setting & participants: Patients in the Veterans Health Administration in 2011 hospitalized (> 24 hours) with at least 2 inpatient serum creatinine measurements, baseline estimated glomerular filtration rate > 60 mL/min/1.73 m², and no diagnosis of end-stage renal disease or non-dialysis-dependent CKD: 17,049 (16.3%) with and 87,715 without AKI.

Predictor: Pattern of recovery to creatinine level within 0.3 mg/dL of baseline after AKI: within 2 days (fast), in 3 to 10 days (intermediate), and no recovery by 10 days (slow or unknown).

Outcome: CKD stage 3 or higher, defined as 2 outpatient estimated glomerular filtration rates < 60 mL/min/1.73m² at least 90 days apart or CKD diagnosis, dialysis therapy, or transplantation.

Measurements: Risk for CKD was modeled using modified Poisson regression and time to death-censored CKD was modeled using Cox proportional hazards regression, both stratified by AKI stage.

Results: Most patients' AKI episodes were stage 1 (91%) and 71% recovered within 2 days. At 1 year, 18.2% had developed CKD (AKI, 31.8%; non-AKI, 15.5%; P < 0.001). In stage 1, the adjusted relative risk ratios for CKD stage 3 or higher were 1.43 (95% CI, 1.39-1.48), 2.00 (95% CI, 1.88-2.12), and 2.65 (95% CI, 2.51-2.80) for fast, intermediate, and slow/unknown recovery. A similar pattern was observed in subgroup analyses incorporating albuminuria and sensitivity analysis of death-censored time to CKD.

Limitations: Variable timing of follow-up and mostly male veteran cohort may limit generalizability.

Conclusions: Patients who develop AKI during a hospitalization are at substantial risk for the development of CKD by 1 year following hospitalization and timing of AKI recovery is a strong predictor, even for the mildest forms of AKI.

Keywords: AKI outcomes; Renal recovery; Veterans Administration (VA); acute kidney injury (AKI); acute on chronic kidney disease; chronic kidney disease (CKD); kidney function; recovery speed; renal complications; serum creatinine.

Conflict of interest statement

Financial Disclosure

None of the authors have any conflict of interest to disclose. All authors employed by the institution associated with their name on the title page and Dr. Zivin is employed by the University of Michigan in addition to the VA Ann Arbor Healthcare Center.

Copyright © 2016 National Kidney Foundation, Inc. All rights reserved.

Figures

Figure 1.

Selection of study cohort. Abbreviations: AKI, acute kidney injury; CKD, chronic kidney disease; d, day(s); ESRD, end-stage renal disease; SCr, serum creatinine. AKI recovery classified by the number of days between peak inpatient SCr and the return of SCr to