Resensitization in suspected penicillin allergy

Abstract

Background:The diagnosis of allergic reactions to penicillins (AR-PEN) is very complex as there is a loss of sensitization over time, which leads to negative skin tests (STs) and specific IgE in serum, and even to tolerance to the drug involved. However, STs may become positive after subsequent exposure to the culprit drug (resensitization), with the risk of inducing potentially severe reactions. The exact rate of resensitization to penicillins is unknown, ranging from 0% to 27.9% in published studies. Objectives:To analyze the rate of resensitization in patients with suggestive AR-PEN by repeating STs (retest) after an initial evaluation (IE). Material and Methods:Patients with suspected AR-PEN were prospectively evaluated between 2017 and 2020. They underwent STs, and a randomized group also underwent a drug provocation test (DPT) with the culprit. Only patients with negative STs and/or DPT were included. All included cases were retested by STs at 2-8 weeks.Results: A total of 545 patients were included: 296 reporting immediate reactions (IRs) and 249 non-immediate reactions (NIRs). Eighty (14.7%) cases had positive results in retest (RT+): 63 (21.3%) IRs and 17 (6.8%) NIRs (p < 0.0001). The rate of RT+ was higher in anaphylaxis compared with all other reactions (45.8% vs 9.1%, p < 0.0001). The risk of RT+ was higher from the fifth week after IE (OR: 4.64, CI: 2.1-11.6; p < 0.001) and increased with the patient's age (OR: 1.02; CI: 1.01-1.04; p = 0.009). Conclusions:Due to the high rate of resensitization, retest should be included in the diagnostic algorithm of IRs to penicillins after an initial negative study, especially in anaphylaxis, to avoid potentially severe reactions after subsequent prescriptions of these drugs.

β-Lactam allergy delabeling is safe and saves costs in Primary Care

“…Recently, Doña et al have described that up to 14 percent of patients with β-lactam allergy presented this resensitization phenomenon. 21 Based in our results, this resensitization phenomenon was notably lower. In this group, only 8 patients (2.04%) were diagnosed having β-lactam allergy in resensitization studies, although other authors give percentages ranging from 0 to 27%.…”

“…In this group, only 8 patients (2.04%) were diagnosed having β-lactam allergy in resensitization studies, although other authors give percentages ranging from 0 to 27%. 21 Whatever the percentage, none delabeling will be not completely reliable if not include a resensitization study after the first negative OPC with the β-lactam involved in the reaction. And why?…”

“…Because it is highly possible that a variable percentage of considered truly delabeled in the first OPC may potentially present a clinical reaction in the next exposure to a β-lactam antibiotic in real-life. 21 …”

Approach for delabeling beta-lactam allergy in children

“…In IRs, it is recommended to perform a retest after an initial negative study if the reaction occurred more than 6 months ago due to the potential loss of sensitization over time, in order to avoid potentially severe reactions after subsequent prescriptions of these drugs ( 148 ). The rate of repositivization in adults has been reported to be 15%, with a potential increase to 45% in cases of immediate severe reactions ( 149 ). The rate of positive retest in children has been reported to be lower, occurring in approximately 2%–5.9% of cases after a positive oral DPT with the culprit ( 31 , 150 ).…”

EAACI/ENDA position paper on drug provocation testing

“…In patients with severe IR to BL more than 6 months before investigation, who display negative results on IgE, skin tests and DPT, a risk of resensitization should be considered 7 . To identify resensitization in remote IRs, few highly specialized centers perform prolonged DPTs on this indication, on an experimental basis, and advice re‐testing with ST or IgE tests 4–6 weeks later 54 …”