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WASHINGTON -- Posters at the American Academy of Allergy, Asthma & Immunology annual meeting provided data about an antibiotic allergy assessment tool via a smartphone app, a direct oral challenge (DOC) for assessing low-risk penicillin allergy labels, and a digital self-assessment tool for the identification of low-risk penicillin and sulfa antibiotic allergies in adults amenable to DOC.

Perioperative Antibiotic Allergy Assessment and Testing

Assessment of antibiotic allergy via a smartphone app by anesthesiologists was safe in delabeling adults with beta-lactam antibiotic allergy labels undergoing planned elective surgery, a pilot randomized controlled trial showed.

The incidence of any kind of adverse event within 90 days was observed in 5.4% of the intervention group compared with 0% of those who received standard of care (P=0.057), reported Joseph De Luca, MBBS, of the University of Melbourne in Australia.

Adverse events in the intervention group included facial numbness/chest pain (2.7%), immune-mediated diffuse rash (1.4%), non-immune-mediated thrush (1.4%), and vocal cord dysfunction (1.4%). As for management, 4% either required no management or self-resolved and 1.4% required use of an oral antihistamine.

Patients with allergy labels for beta-lactams such as penicillin or cephalosporin have worse outcomes in surgery, De Luca told MedPage Today, including more surgical site infections and a higher likelihood of being admitted to the ICU or even death during their admission. "It costs both patients and healthcare services more," he added.

The intervention consisted of an anaesthesiologist assessment via a smartphone app that had been adapted from a previously validated antibiotic allergy assessment tool, followed by directed allergy testing. Drug provocation was conducted in an outpatient clinic with a single dose of either oral amoxicillin 250 mg or phenoxymethylpenicillin 250 mg or cephalexin 250 mg, depending on the index allergy label.

Of the antibiotics used for surgical prophylaxis, 2% of both the intervention and control groups received any form of penicillin, 86% and 82% received any cephalosporin, 11% and 18% received any restricted antibiotic, 7% and 9% received metronidazole, and 4% of both groups received gentamicin.

A total of 150 participants were enrolled in the study, 74 of whom were assigned to the intervention group (median age 67, 49% women, 85% white) and 76 to the standard-of-care control group (median age 67.5, 55% women, 88% white). Sixty-one percent of intervention patients had a form of immunocompromise compared with 43% of control patients.

Among the intervention group, 41% were determined to be very low/low-risk and 59% were determined to be medium/high-risk following assessment. In the control group, 54% of patients were determined to be very low/low-risk, while 46% were medium/high-risk.

All patients included in the study were contacted at 30 and 90 days following their elective surgery at one of three hospital centers in Melbourne to assess for adverse events.

DOC for Assessing Low-Risk Penicillin Allergy Labels

Data from the ORACLE randomized controlled trial showed that DOC can be a safe way to assess low-risk penicillin allergies in critically ill patients and can lead to improved in-hospital antibiotic prescribing.

Among 40 patients in the intervention group, first penicillin DOC outcomes were negative in 98%, reported Morgan Rose, MBBS, of the National Centre for Infections in Cancer at Peter MacCallum Cancer Centre in Melbourne.

DOCs were deemed feasible with a 130/533 eligibility-to-screened ratio, an 80/130 recruitment-to-eligibility ratio, and an 80% protocol compliance.

DOCs also had high validity, with second DOC outcomes also negative in 96.9% of patients.

Critically ill patients are vulnerable to penicillin allergy labels, but are underrepresented in allergy assessment literature, the researchers noted.

"Given that that burden of allergy labels is in that low-risk group, it would be ideal to have a dedicated low-risk clinic that only saw those patients -- you wouldn't need the cost of all the extra training for the time needed for skin testing," Rose told MedPage Today. "You could just have a clinic that was specifically focused on direct oral challenge."

"The problem, though, is that triage step to identify who is low-risk upfront," Rose added. "To then direct them into our clinic is relatively time-consuming. So, I was looking for a way to try and streamline that process to support a dedicated low-risk clinic."

For DOC patients, penicillin utilization increased from 10% pre-intervention to 32% post-intervention compared with an increase of 8% to 10% for patients who received routine care (P=0.019). No significant differences between groups were observed when it came to use of narrow-spectrum penicillin, use of restricted antibiotics, or any antibiotic use.

This open-label study was conducted across four teaching hospital ICUs in Melbourne. Participants with a Penicillin Allergy Decision Rule (PEN-FAST) score <3 were randomized 1:1 to receive DOC with 250 mg of the implicated penicillin versus routine care. Both groups were directly observed for 2 hours after randomization. A repeat DOC was performed in the intervention arm following ICU discharge and >48 hours after first DOC.

A total of 80 patients were included in the trial. Median age was 62.5 in the intervention group, 57% were women, and 80% were white; median Charlson Comorbidity Index was 3 and 30% had obesity. Median age in the control group was 67 years, 42% were women, and 95% were white; median Charlson Comorbidity Index was 4 and 46% had obesity.

Digital Self-Assessment Tool for Identifying Low-Risk Penicillin, Sulfa Allergies

Rose also presented data from a study that showed that digital self-assessment tools may be useful in identifying which patients with low-risk penicillin and sulfa allergies would be amenable to DOC.

Adapted from the PEN-FAST and Trimethoprim-Sulfamethoxazole Allergy Clinical Decision Rule (SULF-FAST) tools, the self-assessment tool had a low-risk positive predictive value of 92.2%, a low-risk negative predictive value of 67.4%, a low-risk sensitivity of 80.4%, and a low-risk specificity of 85.7%.

"The main thing that we've seen is that there is no additional benefit for skin-prick testing in individuals who've been appropriately assessed as low risk," Rose told MedPage Today. "And so in fact, jumping straight to that challenge did not put you at risk of increased positive tests and increased reactions from the testing."

Describing how this process may add to delays for patients, Rose noted that "really all you're doing is you're potentially exposing them to the risks of skin testing, which are small, I absolutely acknowledge, but the challenge there is that you're limited ... if you're relying on skin testing first, then everyone has to be cycling through a clinic."

Patients who were referred to an outpatient antibiotic allergy clinic with a penicillin or sulfa allergy from January to October 2023 were invited to complete the self-assessment via a personalized web link.

A total of 357 participants were included in the study; 66.9% were women, and the median age was 55. Of these participants, 82.3% were allergic to penicillin, 5.9% were allergic to sulfa, and 11.8% were allergic to both.

Of the participants, 63.3% completed the self-assessment, and user satisfaction was 93.1% among those who provided feedback.