β‐Lactam allergy testing and delabeling—Experiences and lessons from Singapore

Abstract

Background: β-Lactam allergy is over-reported and this leads to greater healthcare costs. Allergy testing has inherent risks, yet patients who test negative may continue avoiding β-lactams. Objective: To evaluate the safety and diagnostic value of β-lactams allergy testing locally and usage of antibiotics following negative testing. Methods: We performed a retrospective medical record review and follow-up survey of patients who underwent β-lactam testing between 2010 and 2016 at the National Skin Centre, Singapore. Results: We reviewed the records of 166 patients, with a total of 173 β-lactam allergy labels. Eighty (46.2%) labels were to penicillin, 75 (43.1%) to amoxicillin/amoxicillin-clavulanic acid, 11 (6.4%) to cephalexin, and 5 (2.9%) to others. Skin tests were performed in 142 patients and drug provocation tests (DPTs) in 141 patients. Eleven (6.6%) patients defaulted DPTs after skin testing. Out of 166 patients, 22 (13.3%) patients were proven allergic by either skin tests (16) or DPTs (6). Patients who tested positive had nonsevere reactions. Out of 155 patients who were conclusively evaluated, 133 (85.8%) were not allergic. Of these patients, 30 (22.6%) used the tested β-lactam subsequently, with one reporting a mild reaction. Fifty-one (38.3%) patients were uncontactable or uncertain if they consumed a β-lactam since testing negative. Fifty-two (39.1%) patients had no re-exposure (35 had no indication, 17 were fearful of reactions). Conclusion: Drug allergy testing was safe and removed inappropriate labels. Clinical Implication: Allergy testing is efficacious, but fears of subsequent rechallenge should be addressed to maximize the effectiveness of allergy delabeling.

Beta-lactam allergy in patients: an antibiotic stewardship challenge

“…Most of the labelled patients did not attend the medical appointment to take the challenge and some of them continued to receive non-BL antibiotics in infectious processes after being delabelled. As in other studies, some patients refused to take this type of antibiotics for fear of an allergic reaction 19. This fear, the lack of awareness of the importance of being delabelled or even the panic associated with going to the hospital in a pandemic context were the main reasons why many patients (n=65, 36.9%) did not attend the appointment with the allergist.…”

“…Therefore, collection of the history of antibiotic allergy may be a quality tool to safely increase the proportion of patients receiving BL antimicrobials 18. Traditionally, when a patient was labelled as penicillin-allergic all BL antibiotics were avoided, but a recent meta-analysis showed that the risk of cross-reactivity to carbapenems in penicillin-allergic patients is less than 1% 19. Carbapenems were used in 14 (8.0%) of the patients despite them being labelled as ‘BL-allergic’, and none of them had an allergic reaction.…”

EAACI/ENDA position paper on drug provocation testing

“…7 Many examples of risk stratification and algorithms have been published recently. 7,[33][34][35][36][37][38][39][40][41][42] Whilst focus remains on patient safety, individual risk stratification means, that in patients considered to be at low risk of allergy a diagnosis can be achieved with fewer resources.…”

“…The approach to allergy to beta‐lactam antibiotics has evolved compared to the more restrictive approach recommended previously 7 . Many examples of risk stratification and algorithms have been published recently 7,33–42 . Whilst focus remains on patient safety, individual risk stratification means, that in patients considered to be at low risk of allergy a diagnosis can be achieved with fewer resources.…”