PEN-FAST in pediatrics: a reliable tool for penicillin allergy assessment?

Suspected penicillin allergy presents a significant challenge in the selection and management of antimicrobial therapy for patients. The PEN-FAST clinical decision score was developed and validated to identify individuals at low risk of penicillin allergy. This study aims to assess the applicability of the PEN-FAST scoring system in pediatric patients with a history of penicillin allergy who have undergone diagnostic testing for suspected reactions. Patients aged 6 to 18 years who presented with a history of penicillin allergy to the Pediatric Allergy and Immunology Department of Bilkent City Hospital between January 2017 and November 2024 were included in the study. Demographic, clinical and laboratory data of the patients were obtained from medical records. During the study period, 700 patients with suspected hypersensitivity reactions to penicillins were included. 55.3% were male; the median age at the time of the reaction was 6 years (IQR: 4-9.4). The most frequently implicated penicillin was amoxicillin-clavulanate (91%). Penicillin allergy was confirmed in 64 patients (9.1%). All 64 patients with positive diagnostic test results had a PEN-FAST score of 3 or higher. The performance of the PEN-FAST score ≥ 3 points demonstrated a sensitivity of 100% (95% CI, 0.94-1.00), a specificity of 45% (95% CI, 0.41-0.49), a positive predictive value (PPV) of 15% (%95 CI:0.12-0.19), and a negative predictive value (NPV) of 100% (95% CI, 0.98-1.00). The PEN-FAST score ≥ 3 points revealed a good discrimination in our cohort with AUC of 73% (95% CI, 0.68-0.77).

In outpatient settings, PEN-FAST may facilitate the rapid identification of low-risk patients and aid in the planning of diagnostic testing. New validated point-of-care clinical tools are needed to identify low-risk penicillin allergies in children, and further validation of PEN-FAST is required in larger international cohorts.

• Suspected penicillin allergy presents a significant challenge in the selection and management of antimicrobial therapy for patients. PEN-FAST is a diagnostic tool used to identify low-risk patients for penicillin allergy.

• In our large pediatric cohort, we demonstrated that the PEN-FAST score could be a useful tool for identifying low-risk patients in an outpatient setting. New validated point-of-care clinical tools are needed to identify low-risk penicillin allergies in children, and further validation of PEN-FAST is required in larger international cohorts.