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All children with possible penicillin allergy test negative – small study

Children who, according to their parents, had possible penicillin allergy on the basis of non-specific symptoms all tested negative for actual allergy, a small US study found.

The study involved 100 children ages 4 to 18 years who had low-risk symptoms for a penicillin allergy and underwent a three-tier testing process, reported Dr David Vyles, of Medical College of Wisconsin, and colleagues. Every one came up with negative results with gold-standard evaluation.

The authors said that penicillin is the most commonly reported medication allergy, and that children who present for care in the emergency department are often reported to have such an allergy.

They cited their own recent research, which found that allergy symptoms – adverse reactions such as maculopapular rash, vomiting and diarrhoea – reported by families are low-risk symptoms for a true allergy. But, they added, because there is not a safe, rapid process to diagnose a true penicillin allergy, clinicians in the pediatric ED are reluctant to prescribe the drug to children with these reported symptoms.

Vyles and colleagues used a convenience sample of children from an urban pediatric ED. Parents completed a questionnaire, which included 17 items to assess allergy history, including age of child at allergy diagnosis, name of antibiotic child was taking at diagnosis and symptoms of allergic reaction. They noted it was used in their prior study, where 76% of the children had exclusively "low-risk allergy symptoms." These symptoms included rash, itching, diarrhea, vomiting, runny nose, nausea, cough, or a reported family history of allergy.

Charts of low-risk patients were reviewed before they were invited back for the "gold standard" three-tier allergy testing process for penicillin (percutaneous skin test, intra-cutaneous testing and an oral drug challenge).

Of the 597 completed questionnaires, nearly three-fourths of children (n=434) had low-risk symptoms of allergy to penicillin and 302 were eligible for testing. Of these, 100 children were sent for testing, as that was a number Vyles and colleagues considered adequate to test their hypothesis.

Median age at allergy testing was 9 years (IQR 5-12 years), but the median age at allergy diagnosis was 1 year (IQR 9 months-3 years). Of those tested, 60% were white. The most commonly reported symptom was rash (97%), followed by nearly two-thirds who reported itching. Three-quarters of patients said they received the antibiotic they were allergic to for the treatment of an ear infection.

While over 90% said their child's primary care physician had diagnosed the allergy, after calling all 100 primary care physicians for allergy verification, the authors said that only 14 children had their reaction witnessed by a medical provider – while the rest relied on parent report.

The authors added that only three children had positive results on the first portion of the three-tiered allergy test – the percutaneous skin test – and would have been deemed high-risk by their study criteria. But they said that these children "were never seen by a medical provider and had their allergy diagnosis labeled over the phone." The authors said this indicated "incorrect transmission of information over the phone."

They noted that various studies estimate the true incidence of penicillin allergy to be from 0.004% to 0.015%.

"Consistent with our hypothesis, all children with symptoms deemed to be low-risk for true IgE-mediated drug hypersensitivity ultimately had negative results," the authors wrote, adding that utilisation of the questionnaire in the pediatric ED "may facilitate increased use of first-line penicillin antibiotics."

Previous studies in adults had also determined that many people who report penicillin allergy are not actually allergic.

Abstract
Background: Penicillin allergy is commonly reported in the pediatric emergency department (ED). True penicillin allergy is rare, yet the diagnosis results from the denial of first-line antibiotics. We hypothesize that all children presenting to the pediatric ED with symptoms deemed to be low-risk for immunoglobulin E-mediated hypersensitivity will return negative results for true penicillin allergy.
Methods: Parents of children aged 4 to 18 years old presenting to the pediatric ED with a history of parent-reported penicillin allergy completed an allergy questionnaire. A prespecified 100 children categorized as low-risk on the basis of reported symptoms completed penicillin allergy testing by using a standard 3-tier testing process. The percent of children with negative allergy testing results was calculated with a 95% confidence interval.
Results: Five hundred ninety-seven parents completed the questionnaire describing their child’s reported allergy symptoms. Three hundred two (51%) children had low-risk symptoms and were eligible for testing. Of those, 100 children were tested for penicillin allergy. The median (interquartile range) age at testing was 9 years (5–12). The median (interquartile range) age at allergy diagnosis was 1 year (9 months–3 years). Rash (97 [97%]) and itching (63 [63%]) were the most commonly reported allergy symptoms. Overall, 100 children (100%; 95% confidence interval 96.4%–100%) were found to have negative results for penicillin allergy and had their labeled penicillin allergy removed from their medical record.
Conclusions: All children categorized as low-risk by our penicillin allergy questionnaire were found to have negative results for true penicillin allergy. The utilization of this questionnaire in the pediatric ED may facilitate increased use of first-line penicillin antibiotics.

Authors
David Vyles, Juan Adams, Asriani Chiu, Pippa Simpson, Mark Nimmer, David C Brousseau

[link url="http://www.medpagetoday.com/allergyimmunology/allergy/66388"]Medpage Today report[/link]
[link url="http://pediatrics.aappublications.org/content/early/2017/06/29/peds.2017-0471?sso=1&sso_redirect_count=1&nfstatus=401&nftoken=00000000-0000-0000-0000-000000000000&nfstatusdescription=ERROR%3a+No+local+token"]Pediatrics abstract[/link]

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