353 Contrast-Induced Nephropathy: Determining Risk Factors and Prevalence in Emergency Department Patients Using Modification of Diet in Renal Disease and Chronic Renal Disease Epidemiology Collaboration Formulae in Calculating Glomerular Filtration Rate

Abstract

Background: Contrast-induced nephropathy is defined as a decrease in renal function following administration of radiocontrast material. Clinical practice can be improved by determining the best method to identify contrast-induced nephropathy, and prevalence of contrast-induced nephropathy and co-morbid risk factors. Study Objectives: 1) To determine the prevalence of ED contrast-induced nephropathy using serum creatinine (SCr) and 2 glomerular filtration rate formulae (modification of diet in renal disease [MDRD] and chronic renal disease epidemiology collaboration [CKD-EPI]). 2) To determine which risk factors are associated with development of contrast-induced nephropathy based on MDRD and CKD-EPI. Methods: A retrospective chart review was performed from a convenience sample over 10/2006-4/2008 in a suburban academic ED with 81,000 visits/year. We reviewed ED patients >18 years who received an abdominal, head or chest contrast-enhanced computed tomography and were admitted. We examined the following risk factors for contrast-induced nephropathy: hematocrit <39% men or <36% women, renal disease, proteinuria, past renal surgery, diabetes, congestive heart failure, hypertension or gout. Patients with missing data were excluded; we did not exclude based on initial SCr. Contrast-induced nephropathy was defined as a change in SCr of <25% or 0.5 mg/dL, or a <25% decrease in glomerular filtration rate, 48 hours after contrast. Univariate analyses using the Fischer's exact test were used to compare patients with and without contrast-induced nephropathy for binary risk factorss. Risk factors associated with contrast-induced nephropathy were included in a logistic regression model. Results: We reviewed 92 subjects (51% male); prevalence of risk factors included: 71.7% hypertension, 51% low hematocrit, 26% diabetes, 15.2% proteinuria, 13% congestive heart failure, 7.6% renal disease, 4.3% gout, 3.3% renal surgery, and 1.1% had no associated risk factors. The CDK-EPI, MDRD, and SCr calculations determined 5.43%, 8.79% and 9.78% of subjects developed contrast-induced nephropathy, respectively. A significant percentage of patients with contrast-induced nephropathy per MDRD had gout as a risk factors (25%) compared to subjects without contrast-induced nephropathy who had gout (2.4%; p<0.0374). Subjects with a history of gout were 13.5 times more likely to have a <25% decrease in MDRD (95% CI: 1.6, 113.4) as compared to someone without gout. No other risk factors were associated with contrast-induced nephropathy defined by glomerular filtration rate. Conclusion: The risk factors, and prevalence of contrast-induced nephropathy, varied by method. Further work is necessary to determine which method is most clinically useful. CKD-EPI classifies more patients with contrast-induced nephropathy than MDRD at higher glomerular filtration rates. At sites that see a high number of patients with co-morbidities, like an ED, MDRD may be more useful for assessing risk of contrast-induced nephropathy.