Prevalence of Risk Factors for Contrast-Induced Nephrotoxicity in Outpatients Undergoing Intravenous Contrast-Enhanced Computed Tomography Studies

Objective: To document the prevalence and pattern of risk factors for contrast-induced nephrotoxicity (CIN) in an outpatient population referred for contrast-enhanced computed tomography (CT) (CECT) studies. Methods: Over a 4-month period, 3261 patients presenting for CT studies were asked to consent to a survey of CIN risk factors. Among these patients, 957 were outpatients who received contrast material before the CT study. Demographic information and available serum creatinine (SCr) data for these patients were extracted from medical records and then analysed. A telephone questionnaire to document risk factors was administered to 200 of these patients, who were outpatients not referred from the emergency department or on dialysis. Results: Among the 200 surveyed patients, 69% reported risk factors for CIN or for kidney function impairment (low estimated glomerular filtration rate [eGFR]) at baseline. Among these patients, 43% reported multiple (2 or more) risk factors. Patients older than the mean age of 53 years had a higher incidence of having multiple risk factors when compared with those younger than this age. Patients with kidney function impairment at baseline had a higher incidence of having multiple risk factors when compared with those with normal kidney function. Among the patients with no SCr investigation in the 3 months preceding a CECT, 64% had multiple risk factors. In the study population of 957 outpatients undergoing CECT, 52% had SCr measurements within 3 months before the study. An eGFR of less than 60 mL/min/1.73 m(2) was found in 17% of the study population, and, in 0.6%, the eGFR was less than 30 mL/min/1.73 m(2). Conclusion: In an ambulatory outpatient population, many patients presenting for outpatient CECT studies will have risk factors for GIN or for kidney function impairment (low eGFR) at baseline. Kidney function assessment, therefore, is indicated in this patient population before CECT.