ORIGINAL ARTICLE EXPERIMENTAL ALLERGY AND IMMUNOLOGY Allergy to rocuronium: from clinical suspicion to correct diagnosis J. Leysen 1 , C. H. Bridts 1 , L. S. De Clerck 1 , M. Vercauteren 2 , J. Lambert 3 , J. J. Weyler 4 , W. J. Stevens 1 & D. G. Ebo 1 1 Department of Immunology, University of Antwerp, Antwerp; 2 Department of Anaesthesiology, University of Antwerp, Antwerp; 3 Department of Dermatology, University of Antwerp, Antwerp; 4 Department of Epidemiology and Social Medicine, University of Antwerp, Antwerp, Belgium To cite this article: Leysen J, Bridts CH, De Clerck LS, Vercauteren M, Lambert J, Weyler JJ, Stevens WJ, Ebo DG. Allergy to rocuronium: from clinical suspicion to correct diagnosis. Allergy 2011; DOI:10.1111/j.1398-9995.2011.02569.x. In recent years, neuromuscular blocking agents (NMBA) (such as rocuronium, vecuronium and suxamethonium) have repetitively been reported to constitute a potential cause of life-threatening anaesthesia-related allergy. For decades, physicians have almost uniquely relied upon skin testing to document NMBA allergy and to identify safe alternatives for future surgery (1–6). At present, the speci- ficity of the rocuronium skin test is well established (7–11). In contrast, in the absence of a diagnostic gold standard, sensitivity of the rocuronium skin testing remains elusive. To the best of our knowledge, there are no data available on the predictive value of this skin test. Therefore, when the rocuronium skin test is negative, it is virtually impossi- ble to determine whether it is a false-negative test or whether the patient is tolerant to rocuronium unless the agent is administered. Consequently, additional in vitro tests to diagnose rocuronium allergy are of interest. These tests could not only allow the validation of the skin test but also optimize the diagnosis of rocuronium allergy and reduce erroneous administration of the drug. Recently, quantification of rocuronium-specific IgE (sIgE) (12) and flow-assisted analysis and quantification of rocuronium-acti- Keywords basophil activation test; drug allergy; rocuronium; specific IgE; skin test. Correspondence Prof. Dr. Didier G. Ebo, Department of Immunology-Allergology-Rheumatology, University of Antwerp, Campus Drie Eiken – T4, Universiteitsplein 1, B 2610 Antwerpen, Belgium. Tel.: +32 3 2652595 Fax: +32 3 2652655 E-mail: immuno@ua.ac.be Department to which the work is attributed: Department of Immunology-Allergology- Rheumatology, University of Antwerp, Antwerpen, Belgium. Accepted for publication 3 February 2011 DOI:10.1111/j.1398-9995.2011.02569.x Edited by: Sarbjit Saini Abstract Background: Allergy to rocuronium can be life-threatening. Correct diagnosis is a prerequisite because of serious consequences of diagnostic error. Objective: To assess skin testing, quantification of specific IgE (sIgE) and flow- assisted activation of basophils [basophil activation test (BAT)] in the diagnosis of rocuronium allergy. Methods: This study comprises 104 curarized patients with a history of profound hypotension and severe bronchospasm immediately after induction of anaesthesia. All patients had skin tests, quantification of sIgE and BAT to rocuronium, together with investigations for all relevant compounds administered during anaesthesia that could have evoked the reaction. Diagnosis of rocuronium allergy was considered definite when the patient demonstrated a positive outcome for at least two of the three aforementioned tests. Results: The positive predictive value for skin testing, BAT and sIgE was 98% (CI 95%: 92–99%), 97% (CI 95%: 88–100%) and 83% (CI 95%: 74–89%), respec- tively. The negative predictive value for skin testing, BAT and sIgE was 96% (CI 95%: 86–99%), 75% (CI 95%: 67–75%) and 72% (CI 95%: 58–83%), respec- tively. Cross-reactivity with vecuronium was documented in 69% of the patients. Conclusion: Skin testing merits the status of primary diagnostic investigation to document rocuronium allergy and cannot be substituted by quantification of sIgE or BAT. SIgE can offer a diagnostic advantage in cases where skin tests yield negative results. However, additional tests (e.g. BAT) are of capital impor- tance in patients with negative skin tests and positive sIgE results to help in interpreting the clinical significance of a positive sIgE result. Optimal assessment of cross-reactivity between rocuronium and vecuronium implies both skin test- ing and BAT. Allergy ª 2011 John Wiley & Sons A/S