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Assessing delayed penicillin hypersensitivity using the PENFAST+ score
Julie Castagna1, François Chasset1,2, Jean-Eric Autegarden1
1Médecine Sorbonne Université, Service de dermatologie et d'allergologie, Hôpital Tenon, Assistance Publique des Hôpitaux de Paris (AP-HP), Paris, France.
Insights
The PEN-FAST+ score improves penicillin allergy diagnosis, especially for delayed hypersensitivity reactions. This enhanced tool better identifies patients with low-risk penicillin allergy, reducing misclassifications.
Area of Science:
- Clinical Medicine
- Allergy and Immunology
- Pharmacology
Background:
- Penicillin allergy is over-reported, with low confirmation rates after allergy work-ups.
- The PEN-FAST score aids in identifying low-risk penicillin allergy but has limitations, particularly for delayed hypersensitivity.
- Improving diagnostic accuracy for penicillin hypersensitivity is crucial to avoid unnecessary antibiotic avoidance.
Purpose of the Study:
- To enhance the PEN-FAST score's performance, specifically its negative predictive value for delayed penicillin hypersensitivity.
- To identify additional clinical criteria to improve the accuracy of the PEN-FAST score in diagnosing penicillin allergy.
Main Methods:
- Retrospective evaluation of the PEN-FAST score in patients with confirmed immediate and delayed penicillin allergy.
- Identification of new criteria in misclassified patients to develop the PEN-FAST+ score.
- Prospective validation of the PEN-FAST+ score in a cohort of patients with suspected penicillin hypersensitivity.
Main Results:
- The original PEN-FAST score misclassified a significant proportion of patients with delayed hypersensitivity (37%).
- New criteria, including rash duration and timing/characteristics of immediate reactions, were identified.
- The PEN-FAST+ score demonstrated improved diagnostic performance, with a higher Area Under the Curve (AUC) of 85% compared to PEN-FAST's 72% (p=0.03).
Conclusions:
- The PEN-FAST+ score offers superior diagnostic accuracy for penicillin allergy compared to the original PEN-FAST score.
- This improved score is particularly beneficial for accurately identifying patients with delayed hypersensitivity reactions.
- The PEN-FAST+ score can help reduce misdiagnosis and improve antibiotic stewardship in patients with suspected penicillin allergy.
Introduction:
Approximately 10% of individuals report a suspected allergy to penicillin, but according to allergy work-ups, only 10%-15% of them are truly allergic. A clinical decision score, the PEN-FAST, was developed and validated to identify adults with low-risk penicillin allergy.
Objectives:
The objective of this study was to improve the performance of the PEN-FAST score, particularly for those with delayed hypersensitivity (HS), by improving the negative predictive value.
Methods:
STEP 1: Retrospective evaluation of the PEN-FAST score in patients with proven immediate and delayed penicillin allergy. STEP 2: Identification of additional criteria among Step 1 patients misclassified by PEN-FAST score. Development of the PEN-FAST+ score using multivariable logistic regression in a prospective cohort of patients with a suspicion of HS to penicillin. STEP 3: Comparison of diagnostic performances of PEN-FAST and PEN-FAST+ scores.
Results:
The PEN-FAST score showed limitations in predicting the relapse of immediate skin HS or delayed maculopapular exanthema, with 28.6% and 38.4% of patients misclassified, respectively. We identified two potential additional criteria: skin rash lasting more than 7 days and immediate reaction occurring in less than 1 h (generalized or localized on palmoplantar area or scalp itching/heat feeling). A total of 32/252 (12.7%) patients were confirmed to be allergic to penicillin. With PEN-FAST, 37% of patients (n = 10) with delayed allergic penicillin HS were misclassified. With PEN-FAST+, 3 patients with delayed HS confirmed by a ST (11.1%) were misclassified. The AUC was significantly higher for PEN-FAST+ than PEN-FAST (85% vs. 72%, p = 0.03).
