Is a positive history of non‐anaesthetic drug allergy a predictive factor for positive allergy tests to anaesthetics?
Authors: Hagau Natalia , Gherman‐Ionica Nadia , Hagau Denisa , Tranca Sebastian , Sfichi Manuela , Longrois Dan 
Published: October 2011

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• International recommendations stipulate not to perform skin tests to a drug in the absence of a clinical history consistent with drug allergy.

• In 2006, two publications showed that a positive history of non‐anaesthetic drug allergy was the only predictive factor for allergy to anaesthetic drugs when the screening was done in a general surgical population.

• They concluded that their data supported the international recommendations that a prick test to neuromuscular blocking agents (NMBAs) is indicated only among those patients who have a history to an adverse reaction to them, but at the same time in the case of 2.8% of the patients with no history of peri‐anaesthetic allergy, the NMBA to which they showed a positive prick test was avoided.

WHAT THIS STUDY ADDS

• The novelty of the study is our approach regarding a selected population (volunteers from a general surgical population with a prior history of immediate type hypersensitivity reaction to non‐anaesthetic drugs) in which we performed pre‐operative skin tests andin vitrotests to NMBAs and other anaesthetics.

• Ten per cent of our selected patients had a positive prick test to NMBAs and the results of the basophil activation test (BAT) agreed with prick tests in 83% of patients. BAT is a test that detects IgE mediated effector cell activation, overcoming the concerns related to skin reactivity at different drug concentrations.

• Our results could define a special risk group for intra‐anaesthesia anaphylaxis, and they might lead to the necessity of changing the existing pre‐operative allergy approach.

AIMSInternational recommendations stipulate not performing screening skin tests to a drug in the absence of a clinical history consistent with that specific drug allergy. Nevertheless, two publications showed that a positive history of non‐anaesthetic drug allergy was the only predictive factor for a positive skin test when screening for allergy to anaesthetic drugs was done. We selected from a surgical population 40 volunteers with a prior history of allergy to non‐anaesthetic drugs in order to analyse the prevalence of positive allergy tests to anaesthetics.

METHODSThe selected adult patients were tested for 11 anaesthetic drugs usingin vivotests: skin prick (SPT) and intradermal (IDT) tests andin vitrotests: the basophil activation test (BAT) and detection of drug‐specific immunoglobulin E (IgE).

RESULTSThe prevalence for the positive SPT and IDT was 1.6% and 5.8% respectively. The result of flow cytometry agreed with the SPT in five out of seven positive SPT (71%). IgEs confirmed two positive SPT with corresponding positive BAT. Ten per cent of the patients had a positive prick test to neuromuscular blocking agents (NMBA). For midazolam none of the SPT was positive, but 11 patients had positive IDT nonconfirmed by BAT.

CONCLUSIONThe prevalence of positivein vivoandin vitroallergy tests to NMBAs is higher in our study population. This could be an argument for pre‐operative SPT to NMBAs for the surgical population with reported non‐anaesthetic drug allergies. A larger prospective study is needed to validate changes in clinical practice.