Easy rule identifies patients with low-risk penicillin allergies

Reference

Trubiano JA, Vogrin S, Chua KY, et al. Development and validation of a penicillin allergy clinical decision rule. JAMA Intern Med 2020;180(5):745-752.

Synopsis

This PEN-FAST rule was developed using a group of 622 patients with a history of reacting to penicillin who were referred for allergy testing, and then validated on a second group of 945 patients who were referred for allergy testing at 3 other sites. Allergy testing consisted of skin prick, intradermal, or patch testing, with positives confirmed by oral challenge. In the validation group, 27.4% reported a history of angioedema and/or anaphylaxis. Following testing in this group, the prevalence of reacting to any allergy test was 9.9%, but only 21 participants reacted to the oral challenge (2.2%). For patients who report a PENicillin allergy, here is the FAST rule: F (five years or less since the reaction): 2 points A (anaphylaxis or angioedema) or S (severe cutaneous reaction): 2 points T (treatment required for reaction): 1 point Patients with a score of 0 had a likelihood of a positive test result of less than 1%; a score of 1 or 2 yielded a positive test result in 5%. Among the 3 cohorts, sensitivity ranged from 70.4% (prevalence 27%) to 87.5% (prevalence 14.4%).