Table 1. Diagnosis and prevention of immediate HSRs to ICM presented in each clinical guideline.

Clinical guideline	Diagnosis	Premedication	Change and selection of alternative contrast agent
American College of Radiology7	• No specific mention of a diagnostic test.	• Administering oral corticosteroids 12–13 hours before ICM exposure is recommended to patients who have previously experienced immediate HSRs to ICM.	• If culprit ICM is known in patients who have previously experienced immediate HSRs to ICM, a change of the ICM from the culprit to an alternative ICM is recommended.
	• Performing skin tests routinely before CT scan with ICM is not recommended to predict immediate HSRs.	• If it is difficult to perform an ICM-related skin test, administering intravenous corticosteroid 4–5 hours before ICM exposure is recommended to patients who have previously experienced immediate HSRs to ICM.	• No specific mention of alternative ICM selection
		• No classification for severity of HSRs
European Society of Urogenital Radiology8	• Consulting to allergist within 1–6 months is recommended for patients with a previous history of moderate to severe HSRs to ICM.	• Premedication is not recommended due to insufficient evidence.	• A change of the ICM from the culprit to an alternative ICM is recommended for patients who have previously experienced immediate HSRs to ICM
			• Performing skin tests in consultation with an allergist can help to select an alternative ICM
European Academy of Allergy and Clinical Immunology (EAACI) position paper9	• Skin test is recommended in all patients who have previously experienced immediate HSRs to ICM, except for emergent CT scan with ICM.	• Premedication is recommended for patients who have previously experienced immediate HSRs to ICM or have a difficult situation to perform a skin test due to an emergent CT scan with ICM.	• A change of the ICM from the culprit to a skin test-negative alternative ICM is recommended for patients who have previously experienced immediate HSRs to ICM.
	• DPT can be used to identify suitable alternative ICMs in patients with a negative skin test.	• No classification for severity of HSRs	• Patients having experienced ICM-induced anaphylaxis are recommended to avoid CT scans with ICM. If it is necessary to perform a CT scan with ICM, a replacement to an alternative ICM and a preparation of emergency medicine are recommended.
Spanish Society of Allergy and Clinical Immunology (SEAIC)10	• Skin test is highly recommended for patients who have previously experienced immediate HSRs to ICM.	• The preventive effect of pretreatment is controversial.	• A replacement to an alternative ICM by skin test is recommended for patients who have previously experienced immediate HSRs to ICM.
	• DPT is recommended to confirm an alternative ICM.

HSR, hypersensitivity reaction; ICM, iodinated contrast media; DPT, drug provocation test.