We aimed to assess an intervention implemented in our Allergy Clinic to de-label non-HIV patients with self-reported sulfonamide allergy utilizing a previously published test-dose challenge of trimethoprim-sulfamethoxazole (TMP-SMX). A pre-/post-intervention, quality improvement design in patients with self-reported non-severe delayed, immediate or unknown reaction to TMP-SMX. We compared the effectiveness of a one-to-two step test-dose versus a 6-step desensitization of TMP-SMX. The main outcome measure was the rate of success for desensitization versus test-dose. Patients were contacted in the test-dose group via phone to evaluate safety of further TMP-SMX administration. Cost for each procedure was estimated based on current Medicare standards. A total of 52 patients underwent sulfonamide desensitization in the two-year (2017-2018) pre-intervention period and were compared with 53 patients who underwent test-dose administration of TMP-SMX in the two-year (2019-2020) post-intervention period. In both periods, most patients were female (87% versus 75%), white (85% versus 96%), and over 60 years of age (60% versus 58%). In the test-dose group, 51% underwent a two-step test-dose. The success rates of desensitization and test-dose were similar (94% versus 90%; P = .72). In the test-dose group, none of the 37 patients who received a course TMP-SMX post de-labeling reported an adverse drug reaction. The estimated post-intervention cost reduction was $13,217. The implementation of a validated protocol for graded administration of TMP-SMX revealed similar success rates than desensitization, with a decrease cost, and without an increase of adverse events.
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