Looking backward at the future of AKI: A retrospective cohort study on the clinic-pathological variables affecting renal recovery after acute kidney injury

Introduction: Acute kidney injury (AKI) is no longer considered a single hit disease but part of a spectrum that culminates in adverse renal and cardiovascular outcomes. What are the renal biopsy findings of patient with persistent AKI/AKD (acute kidney disease)? Are there renal biopsy characteristics which predict renal recovery. These are the questions that this study addresses. Methodology: A retrospective study was conducted analyzing all patients who underwent a renal biopsy with a diagnosis of acute kidney injury from January 2021 to January 2023 from the online hospital database. Patients with other glomerular disease and transplant patients were excluded from this cohort. The clinical and renal biopsy characteristics were analyzed for their correlation with renal recovery. Results: Of 420 patients screened, 54 were included in the study. Most patients had stage 3 AKI. The median follow up in this study was 80.50 days. Among those on dialysis, 55.6% of patients became free of KRT (kidney replacement therapy). 92.6% of the study population had diffuse tubular involvement on the renal biopsy. Clinical recovery correlated with the degree of vasculature involvement on the renal biopsy. Interstitial fibrosis and tubular atrophy corelated with progression to CKD. Among the clinical features, the cause of AKI, presence of pre-existing CKD and Charleston co-morbidity score correlated with independence from KRT. Conclusion: Specific findings on the renal biopsy such as atherosclerotic changes correlate negatively with long-term recovery in AKI and renal biopsy findings of interstitial fibrosis and tubular atrophy may help to prognosticate progression to CKD.. Among clinical characteristics, the presence of co-morbidities and pre-existing CKD correlates negatively with renal recovery.