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March 16, 2020
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New penicillin allergy clinical decision rule helps de-label low-risk patients

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A new point-of-care clinical decision tool, PEN-FAST, may help identify patients with reported penicillin allergies who can safely undergo oral challenges and receive beta-lactam antibiotics without needing formal allergy testing, according to research published in JAMA Internal Medicine.

Jason A. Trubiano, MBBS, PhD, director of antimicrobial stewardship and drug and allergy services at Austin Health in Heidelberg, Australia, and colleagues explained that although formal antibiotic-allergy testing has been incorporated into antimicrobial stewardship programs, it “requires specialist interpretation, is labor intensive, and is potentially unwarranted, considering that less than 10% of penicillin allergies may be confirmed by formal testing results.”

The researchers sought to create a point-of-care clinical decision rule to address the high burden of falsely labeled penicillin allergies, stratify individuals’ risks, and facilitate appropriate de-labeling and prescribing efforts.

Trubiano and colleagues analyzed data from a prospective study of 622 patients who were antibiotic-allergy tested at two tertiary sites in Melbourne, Australia, and were used for derivation and internal validation of the penicillin allergy decision rule. They used backward stepwise logistic regression when deriving the model, which included clinical characteristics that predict positive penicillin allergy test results.

Reference: Trubiano JA, et al. JAMA Intern Med. 2020;doi:10.1001/jamainternmed.2020.040.

Data from three retrospective cohorts — two in Australia and one in the United States — with a total of 945 patients were used for external validation. In these cohorts, patients with reported penicillin allergies had skin prick testing, intradermal or patch testing and/or oral challenge.

Trubiano and colleagues classified a low-risk penicillin allergy as less than 3 points in PEN-FAST. The major criteria were an allergy event that occurred within the last 5 years, anaphylaxis or angioedema or a severe cutaneous adverse reaction — each worth 2 points — and the minor criteria was needing treatment for an allergy episode, worth 1 point.

In internal validation, the researchers found that the test had minimal mean optimism of 0.003, and an internally validated area below the curve of 0.805.

Among the 460 patients in the validation cohort who were classified as low-risk, 3.7% tested positive on penicillin allergy testing, creating a negative predictive value of 96.3% (95% CI, 94.1-97.8).

The researchers reported that external validation yielded similar results.

“This finding is important because penicillin allergy is increasingly recognized as a public health issue for communities and hospitals, with well-described deleterious effects on patients and health,” Trubiano and colleagues wrote. “PEN-FAST potentially allows clinicians to evaluate penicillin allergy risk and severity, thereby encouraging the safe use of -lactams and oral challenge programs in those patients considered to be at low risk of penicillin allergy,” they wrote. – by Erin Michael

Disclosures: Trubiano reports no relevant financial disclosures. Please see study for all other authors’ relevant financial disclosures.