Concordance of Prebiopsy and Postbiopsy Diagnosis in Hospitalized Patients with Acute Kidney Injury

KEY POINTS: Kidney biopsy remains the gold standard for diagnosis of kidney disease. Prebiopsy and postbiopsy diagnosis concordance is low for acute interstitial nephritis and acute tubular injury. BACKGROUND: Percutaneous kidney biopsy remains the gold standard for evaluation of AKI, given that clinicians' prebiopsy clinical impression of AKI, on the basis of history, examination, and noninvasive testing may not lead to a unifying diagnosis. In this study, we evaluated the concordance of prebiopsy clinical diagnosis with postbiopsy final diagnosis among patients with clinical AKI. METHODS: We leveraged data collected prospectively through the Novel Approaches in the Investigation of Kidney Disease Study between 2020 and 2023, in which adult patients admitted to the Johns Hopkins Hospital and scheduled for clinical kidney biopsies consented to provide biosamples paired with data collection. Up to three prebiopsy clinical diagnoses were recorded for each patient, along with up to three postbiopsy diagnoses, adjudicated by a study nephrologist postbiopsy. We investigated the concordance of prebiopsy and postbiopsy diagnoses among patients with suspected acute interstitial nephritis (AIN) or acute tubular injury (ATI). RESULTS: Among 164 total participants, 29 patients had a suspected clinical diagnosis of AIN and 47 had a suspected clinical diagnosis of ATI prebiopsy. Among the participants with suspected AIN, only seven (24%) had AIN confirmed on biopsy. Of the 22 biopsies without AIN present, alternative diagnoses noted on histology included FSGS, ATI, and various glomerular diseases. Of 47 participants with suspected ATI, ATI was confirmed on biopsy in 27 (57%) participants. In the 20 biopsies without ATI present, alternative histological findings also included glomerular diseases, diabetic nephropathy, and FSGS predominantly. CONCLUSIONS: Patients with suspected ATI or AIN who undergo percutaneous kidney biopsy are often found to have alternative, significant findings present on histology. Among patients without relative or absolute contraindications, kidney biopsy remains an essential part of clinical evaluation, while future research should focus on the development of noninvasive approaches for kidney disease diagnosis.