Using kidney size for early detection of contrast-induced nephropathy in the emergency department setting

Aim: We aimed to examine the relationship between kidney size and contrast-induced nephropathy (CIN) in patients who underwent contrast-enhanced computed tomography (CT) in the emergency department. Methods: This single-center retrospective observational study was undertaken to evaluate risk factors for CIN at Okayama Saiseikai General Hospital (Okayama, Japan) from January 2014 through to December 2016. Contrast-induced nephropathy was defined as an absolute increase in serum creatinine level of ≥0.5 mg/dL or ≥25% over the baseline value within 72 h after contrast-enhanced CT. Independent risk factors for CIN were determined by multiple logistic regression analysis. The thickness of the kidney was evaluated as a predictor of CIN using the area under the receiver operating characteristic curve. We also analyzed CIN as an outcome using the Kaplan-Meier method. Results: The incidence of CIN was 26/262 (9.9%). In the multivariate analysis, CIN was associated with renal thickness (odds ratio = 0.65; 95% confidence interval, 0.53-0.81). No patient underwent renal replacement therapy. Conclusion: Renal thickness could be used as a reliable, simple, and easily obtainable marker for identifying CIN in patients undergoing contrast-enhanced CT in the emergency department.