Optimal step doses for drug provocation tests to prove beta-lactam hypersensitivity

Abstract

Background

Drug provocation tests (DPT) are commonly performed as part of ß-lactam allergy work-up, in case of negative skin tests, and in the absence of contraindications. The recommendations of learned societies have created a frame for DPT performance, but protocols vary widely between centres, generating various hypothesis-driven protocols (i.e., empirical dosing, driven by both safety concerns and practical aspects).

Methods

The primary objective of this retrospective analysis was to detect eliciting dose thresholds (reactive doses) during ß-lactam DPT, using the survival analysis method, in order to suggest optimal step doses. Our secondary objective was to evaluate the safety of our 30-minute incremental one-day protocol. The study included all the patients explored in the Allergy Unit of the University Hospital of Montpellier (France), between September 1996 and July 2015 for a suspicion of drug hypersensitivity reaction to ß-lactams, with negative skin tests and positive DPT.

Results

During the study period, 182 positive DPT (accounting for 171 hypersensitive patients) were analysed. We identified eliciting thresholds and we suggest the following steps for DPT to ß-lactams: 5%-15%-30%-50% of daily therapeutic dose (with additional lower steps for index reactions of anaphylaxis). We confirm the safety of one-day protocol for immediate and mild non-immediate reactors, for both children and adults, with a surveillance period of 2h after the last administered dose, and a prolonged surveillance after discharge of 48 hours.

Conclusion

This data-driven approach in designing DPT protocols is a step forward in improving DPT standardization, starting with the most frequently tested drugs, ß-lactam antibiotics.

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