“This Contrast Medium Will not Burn at All.” Unintended Nocebo Effects and Considerations for the Design of Clinical Trials

Abstract

iobitridol : 5 ; iomeprol : 3 ; iodixanol : 1 ; iopentol : 1 ;iopromide : 1). Three patients had a history of previous reaction. Cutaneous reactions (grade 1) occurred in 10 patients, moderate systemic reactions in 9 and life-threatening in 6. Fifteen patients had biochemical studies, 2 had increased concentrations of histamine and tryptase. Sixteen patients went for skin testing, among them 6 had had biochemical measurements. All of them had negative skin Prick tests to the involved CM. One had a positive Prick test to latex, with positive latex IgE, indicating that latex was responsible for the reaction. Eight (including the 2 patients with increased concentrations of mediators, but no patient with normal values) had positive intradermal tests, with the involved CM diluted 1 :100 (2 patients) ; 1 :10 (5 patients), or with the pure ICM (1 patient). The responsible CM were : ioxaglate : 3 ; iomeprol : 2 ; iodixanol : 1 ; iobitridol : 1 ; iohexol : 1. Three of them had also positive skin tests to 2 other CM, indicating cross reactivity between different CM.