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 of chronic kidney disease (CKD), even following apparent renal recovery. Whether pattern of renal recovery predicts kidney risk following AKI is unknown. Study Design: Retrospective cohort. Setting and Participants: Patients in the Veterans Health Administration in 2011 hospitalized (> 24 hours) with at least two inpatient serum creatinine measurements, baseline eGFR > 60 ml/min/1.73m2 and no diagnosis of CKD or ESRD: 17,049 with AKI (16.3%) and 87,715 without. Predictor: Pattern of recovery to creatinine within 0.3 mg/dl of baseline after AKI: within 2 days (fast), between 3 and 10 days (intermediate), and no recovery by 10 days (slow or unknown). Outcome: Stage 3 or higher CKD, defined as 2 outpatient eGFRs <60 ml/min/1.73m2 at least 90 days apart or a CKD diagnosis, dialysis, or transplant. Measurements: Risk of CKD was modeled using modified Poisson regression and time to death-censored CKD modeled using Cox proportional hazards regression, both stratified by stage of AKI. Results: Most patients’ AKI episodes were Stage 1 (91%) and 71% recovered within two days. At one year, 18.2% had developed CKD (AKI: 31.8%, non-AKI: 15.5%, p<.001). In stage 1, the adjusted relative risk ratios (RR) for Stage 3 or higher CKD were 1.43 (95% CI 1.39–1.48), 2.00 (95% CI 1.88–2.12), and 2.65 (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 development of CKD by one year following hospitalization and timing of AKI recovery is a strong predictor, even for the mildest forms of AKI.