Prophylaxis in High-Risk Patients With eGFR < 30 mL/min/1.73 m2: Get the Balance Right Objectives Clinical guidelines recommend prophylactic intravenous fluids for patients with estimated glomerular filtration rate (eGFR) less than 30 mL/min/1.73 m2 to prevent adverse postcontrast outcomes. These patients represent a small minority of the population receiving intravascular iodinated contrast material, and data are not readily available. The current study aim is to gain insight into positive and negative effects of prophylaxis by comparing postcontrast outcomes in high-risk patients who did and did not receive prophylaxis. Materials and Methods Observational data were gathered over 4 years. Inclusion criteria were age 18 years or older, eGFR less than 30 mL/min/1.73 m2, and elective intravascular iodinated contrast administration. Exclusion criteria were dialysis and nonstandard periprocedural prophylaxis. Primary outcome was postcontrast acute kidney injury (>25% or >44 μmol/L serum creatinine increase within 2–5 days). Secondary outcomes were change in eGFR, 5 mL/min/1.73 m2 or greater eGFR decline, dialysis, and mortality at 1 month postcontrast including primary cause, as well as complications of prophylaxis. Results were stratified by contrast procedure type and corrected for potential confounders. Results Of all 55,474 elective procedures with intravascular contrast administration, 362 patients met the inclusion criteria: 281 (78%) received standard 0.9% NaCl prophylaxis and 81 (22%) received no prophylaxis. Prophylaxis versus no prophylaxis adjusted odds ratios were nonsignificant and less than 1 for postcontrast renal outcomes (postcontrast acute kidney injury, eGFR decline, dialysis), indicating a trend toward a protective effect of prophylaxis. For mortality, adjusted odds ratios were nonsignificant and greater than 1, indicating a trend toward higher mortality risk after prophylaxis. Of the primary causes of death analyzed in prophylaxis patients, 24% (5/21) were related to prophylaxis. Among 281 prophylaxis patients, 18 (6.4%) complications of prophylaxis occurred: 15 heart failures and 3 arrhythmias. Conclusions Based on this study, no standard recommendation with regard to giving or withholding prophylaxis can be given. Prophylactic fluids may confer some protection against postcontrast renal adverse events but may also contribute toward increased risk of short-term death. In this setting, benefits and risks of prophylaxis must be carefully weighed and cardiac parameters assessed for each individual patient. Received for publication February 8, 2019; and accepted for publication, after revision, March 14, 2019. Conflicts of interest and sources of funding: The authors declare no conflicts of interest. The study was funded by Stichting de Weijerhorst. Supplemental digital contents are available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.investigativeradiology.com). Correspondence to: Estelle C. Nijssen, MSc, Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre, PO Box 5800, 6202 AZ Maastricht, the Netherlands. E-mail: estelle.nijssen@mumc.nl. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.