A new study suggests that direct oral penicillin challenge (DOC) is an effective method for removing penicillin allergy labels, with this delabeling remaining effective for up to six months in most individuals. The research, led by Ana Maria Copaescu, MD, from the Research Institute of the McGill University Health Centre, found that formal testing typically confirms fewer than 5% of penicillin allergies, though persistent or incorrect labeling can still occur.
The analysis, based on the Penicillin Allergy Clinical Decision Rule (PALACE) study, examined long-term follow-up and risks associated with allergy persistence. The study compared the efficacy of DOC with traditional penicillin skin testing followed by an oral challenge. It focused on adult participants with a low-risk penicillin allergy, indicated by a Penicillin Allergy Decision Rule (PEN-FAST) score of less than 3.
Researchers conducted a six-month follow-up using a scripted telephone questionnaire to assess recurrence of penicillin allergy, adverse events (AEs), and other related factors. Statistical analysis employed univariable and multivariable logistic regression, with a significance threshold set at P < .05.
Of 377 individuals initially delabeled, 93.1% completed the follow-up. The study found that 6.6% experienced suspected recurrent penicillin allergy, with 13 out of 178 in the intervention cohort and 10 out of 173 in the control cohort. Additionally, 9.7% of participants reported avoiding penicillin by the six-month mark.
Among those reporting suspected recurrent allergies, 47.8% had experienced an AE within the initial study period, while 30.4% reported new AEs, and 21.7% had suspected recurrent allergies without accompanying AEs. Immune-mediated AEs were linked to 11 of 13 new penicillin-based therapies.
The study identified a strong association between suspected recurrent allergies and immune-mediated AEs occurring after the initial study period (odds ratio, 35.44; 95% CI, 9.40-133.60; P < .001). No baseline characteristics correlated with recurrent allergies. Notably, 73.9% of individuals with suspected recurrent allergies had used antibiotics, including penicillin-class drugs, within six months.
Limitations of the study include the lack of direct medical record review to document allergy labels and the persistence of patient reluctance to take penicillin despite successful delabeling and absence of AEs.
