Premedication for Iodinated Contrast Media Induced Immediate Hypersensitivity Reactions

Abstract

Purpose of the review Premedication using antihistamines and/or corticosteroids has been widely used to prevent reoccurrence of immediate hypersensitivity reactions (iHR) after iodinated contrast media (ICM). However, efficacy has been debated, especially in high-risk patients. Novel findings on the role and risks of premedication and preventive strategies are summarized. Recent findings The rate and severity of iHR occurring despite premedication indicate that premedication is not a panacea and the intensity usually reflects that of the initial reaction. Next, the number needed to treat (NNT) to prevent one serious ICM-mediated event using corticosteroid-based premedication is high and associated with a diagnostic delay. Randomly changing the ICM has been suggested as an additional preventive measure, whilst others used a skin test-based approach to identify a subgroup of ICM allergic patients and negative skin test-based alternatives with a high negative predictive value. Summary Growing evidence indicates the need to discriminate between non-allergic iHR that are most likely non-obligatory and susceptible to premedication, and rare type I allergic iHR

Pharmacological prevention of delayed hypersensitivity reactions caused by iodinated contrast media

“…However, the total amount of steroids prescribed to patients was similar to the amount generally recommended for premedication for immediate RCM hypersensitivity reactions. 20 , 39 In line with the opinions of expert groups, we support that the benefits of pharmacological prevention could outweigh the potential harm. 40 …”

Practice parameters for diagnosing and managing iodinated contrast media hypersensitivity

“…The minimal interval for premedication administration is unknown. A 12‐hours or 13‐hours oral scheme of corticosteroids is usually recommended but an accelerated intravenous scheme is proposed when the multidose schedule is not feasible 54,55 …”

“…54,55 Premedication has not been considered sufficient and might not even be indicated in patients with a history of true IgE-mediated ICM anaphylaxis. 55,63,64 Lee et al observed 6/9 selected high-risk patients to be ST positive, 54 and Marshall et al observed 2/10 positive DPTs, 60 indicating a subgroup of type I allergic patients.…”

Should we be less reactive about contrast reaction prophylaxis?

“…Most contrast reactions are nonallergic and are due to non‐IgE‐mediated histamine release from basophils and/or mast cells, or other mechanisms such as complement activation and bradykinin formation 3 . Breakthrough reactions despite premedication can occur in up to 50% of cases; conversely, in patient with prior reactions who received the same contrast without premedication, <1/3 had recurrent reactions 3 .…”

“…Most contrast reactions are nonallergic and are due to non‐IgE‐mediated histamine release from basophils and/or mast cells, or other mechanisms such as complement activation and bradykinin formation 3 . Breakthrough reactions despite premedication can occur in up to 50% of cases; conversely, in patient with prior reactions who received the same contrast without premedication, <1/3 had recurrent reactions 3 . True allergic reactions are due to IgE‐mediated drug allergy and fortunately severe reactions are very rare; in that setting, experts have noted that the efficacy of premedication is absent and the specific contrast agent the patient is allergic to should be avoided 3 …”