Incidence of Nonconfounded Post–Computed Tomography Acute Kidney Injury in Hospitalized Patients with Stable Renal Function Receiving Intravenous Iodinated Contrast Material

ObjectiveThe purpose of our investigation was to determine the frequency of proximate acute and chronic confounding risk factors for acute kidney injury (AKI) in a cohort of adult hospitalized patients with stable renal function who developed AKI following an intravenous (IV) contrast-enhanced computed tomography (CT) examination.Materials and MethodsInstitutional review board approval was obtained for this retrospective, Health Insurance Portability and Accountability Act–compliant investigation. Overall, 100 adult inpatients (50 males [mean age = 61 years, range: 24-94 years] and 50 females [mean age = 60 years, range: 20-95 years]) with stable pre-CT renal function who developed post-CT AKI using the Acute Kidney Injury Network (AKIN) laboratory criteria following an IV contrast-enhanced CT examination comprised the study population. Electronic International Classification of Disease-9 analysis followed by a comprehensive manual electronic medical record review was systematically performed by 5 radiologists to identify known acute (n = 24, within 5 days before or 3 days after CT) and chronic (n = 21) risk factors for AKI other than contrast material administration that might confound a diagnosis of contrast-induced nephrotoxicity. Descriptive statistics were performed.ResultsOf 100 inpatients with post-CT AKI, 99 (99%) had 1 or more acute risk factor(s) for AKI other than contrast material administration (median = 3 risk factors, range: 0-8) and 86 (86%) had one or more chronic risk factor(s) for AKI (median = 2 risk factors, range: 0-7). The median number of risk factors (acute or chronic) per patient was 5 (range: 1-13). Only 1 inpatient (1%) developed post-CT AKI without a confounding acute risk factor (estimated glomerular filtration rate = 62-71 mL/min/1.73 m2, 4 chronic risk factors, and CT 7 days after pancreaticoduodenectomy). The most common acute risk factors were nephrotoxic medications (83%) and parenteral blood product administration (30%). The most common chronic risk factors were hypertension (59%) and chronic kidney disease (56%).ConclusionNonconfounded post-CT AKI is rare in hospitalized adults with stable renal function who have been exposed to IV low- or iso-osmolality iodinated contrast material.