Penicillin allergy may be safely ruled out by direct oral penicillin challenge alone: JAMA

Dr Ana explained the study background and said that fewer than 5% of patients who are labeled with a penicillin allergy are truly allergic. The standard of care to remove this allergy label involves specialized testing, which requires prick and intradermal skin testing, followed by an oral challenge with penicillin. Skin testing is resource intensive, limits practice to specialist-trained physicians, and restricts the global population who could undergo penicillin allergy delabeling.

This background was further investigated in this study of 382 patients across six centres in 3 countries in an attempt to determine the efficacy of a clinical decision rule to enable direct oral challenge in patients with low-risk penicillin allergy.

This study is published in JAMA Internal Medicine.

The key points of the study are:

• The study population included 130 men and 247 women.
• Adults were greater than 18 years of age with low-risk penicillin allergy.
• The median age of the participants was 51 years.
• The study was conducted in six hospitals in North America and Australia.
• Three hundred seventy-seven participants were analyzed: 190 in the control group and 187 in the intervention group.
• Participants in the control group underwent skin prick and intradermal penicillin testing followed by oral challenge if skin testing results were negative.
• Participants in the intervention group had a direct oral penicillin drug challenge.
• The primary outcome was between-group differences in the proportion of participants with a physician-verified immune-mediated positive oral penicillin challenge (percentage points); the noninferiority margin was set at five percentage points.
• They found that the proportion of participants with a positive oral penicillin challenge in control and intervention was 1/190 and 1/187, constituting 0.5 % and 0.5 %, respectively. The risk difference was 0.0084.

They said the intervention was non-inferior to the control for the primary outcome in adults with low-risk penicillin allergy.

They noted that direct oral penicillin challenge is a safe procedure to facilitate the removal of a penicillin allergy label among those with low-risk history.

Further reading:

Copaescu AM, Vogrin S, James F, et al. Efficacy of a Clinical Decision Rule to Enable Direct Oral Challenge in Patients With Low-Risk Penicillin Allergy: The PALACE Randomized Clinical Trial. JAMA Intern Med. Published online July 17, 2023. doi:10.1001/jamainternmed.2023.2986