Comparison of patient comfort between iodixanol and iopamidol in contrast-enhanced computed tomography of the abdomen and pelvis: a randomized trial

Background: Previous clinical studies have shown that iso-osmolar iodixanol (Visipaque (R)) causes less patient discomfort than low-osmolar contrast media (LOCM) when administered via intra-arterial injection. No data are available comparing these agents for patient discomfort when administered intravenously (i. v.) using power injectors. Purpose: To compare the frequency and intensity of patient discomfort between iodixanol and iopamidol (Isovue (R)) administered i. v. using a power injector in contrast-enhanced computed tomography (CECT) of the abdomen and pelvis. Material and Methods: This was a prospective, randomized, double-blind, multicenter study of iodixanol 320 mg I/mL or iopamidol 370 mg I/mL on patient discomfort. The presence of discomfort (heat, pain, coldness) and intensity was verbally rated by patients on a 0-10 scale and converted into four categories (0, none; 1-3, mild; 4-7, moderate; 8-10, severe). Image quality was evaluated. Results: Of the 299 evaluable patients enrolled at nine centers, 151 received iodixanol and 148 received iopamidol. The average age was 58 years. Iodixanol patients experienced significantly less moderate/severe discomfort (35.1% vs. 67.3%; P< 0.0001) or heat (29.8% vs. 63.9%; P< 0.0001), and severe discomfort (2.6% vs. 16.3%; P 0.0004) or heat (2.6% vs. 15%; P 0.0008), but three times more no discomfort (21.2% vs. 7.5%; P = 0.0008) than iopamidol patients. Excellent image quality was in 95.4% of iodixanol vs. 89.9% of iopamidol patients (P = 0.0508). Overall, adverse event (AE) rate excluding patient discomfort was 19.9% in the iodixanol group and 14.9% in the iopamidol group (P = 0.2870), but contrast-related AEs were comparable: 11.3% vs. 10.1% (P = 0.8522). Delayed skin reactions occurred in 2.6% of patients in the iodixanol group and in no patient in the iopamidol group (P = 0.1226). Conclusion: Patients receiving iodixanol had significantly lower moderate-to-severe or severe discomfort than patients receiving iopamidol, with heat being the major contributor. Iodixanol use trended towards better image quality but the difference was not statistically significant. No significant differences in incidences of overall or contrast-related AEs or delayed skin reactions were seen between the two groups. These data support that CM osmolality may be a key determinant of patient discomfort.