Does This Emergency Department Patient Have a Penicillin Allergy?
Article Outline
Methods
Data Sources
An English-language MEDLINE search from 1996 to 2000 was conducted, and the bibliographies were reviewed for additional references.
Study Selection
Original studies describing the accuracy or precision of skin testing in the diagnosis of an immunoglobulin E–mediated penicillin allergy were included. Fourteen studies met the inclusion criteria; 4 studies compared clinical history with skin test results in patients with and without a history of penicillin allergy.
Data Extraction and Synthesis
Confidence intervals for the likelihood ratios of having a positive skin test result, given a positive history of penicillin allergy, and having a negative skin test result, given a history of no penicillin allergy, were compared. Sensitivity and specificity for a history of penicillin allergy versus skin testing were also presented.
Patients reporting a history of non–type 1 allergy to penicillin can safely be administered penicillin
Commentary
This systematic review emphasizes obtaining an accurate history to decide whether or not the patient who reports a penicillin allergy is likely to have had a type 1 reaction. The review suggests that those who report a history of a nonlife-threatening type 1 reaction should be skin tested, whereas those whose reaction is not likely to be type 1 may be administered penicillin without skin testing.
Although investigators have recently demonstrated the feasibility of emergency department skin testing,1 this is uncommon practice in most settings. Furthermore, in 2 studies, a significant portion of patients with negative skin-testing results had an immediate reaction to penicillin challenge,2, 3 reminding us that the criterion standard for predicting reactions is drug challenge, not skin testing. This suggests that those with a potentially serious allergy should simply avoid penicillin whenever possible.
However, the majority of patients reporting a penicillin allergy report a maculopapular, nonurticarial rash or other non–type 1 reactions; a detailed history can identify these patients accurately. This select group appears to have a likelihood of reaction (roughly 5%) consistent with the chance of reaction in a general population, making use of penicillin appropriate and safe.
Results
The Table below reflects results from 4 studies (n=9,526) of moderate quality.
Patient history of penicillin allergy as a predictor of positive skin test result
| Positive LR (95% CI) | Negative LR (95% CI) |
|---|---|
| 1.9 | 0.5 |
| (1.5–2.5) | (0.4–0.6) |
References
- The use of penicillin skin testing to assess the prevalence of penicillin allergy in an emergency department setting. Ann Emerg Med. 2009;54:72–77
- Controlled administration of penicillin to patients with a positive history but negative skin and specific serum IgE tests. Clin Exp Allergy. 2002;32:270–276
- Drug provocation tests in patients with a history suggesting an immediate drug hypersensitivity reaction. Ann Intern Med. 2004;140:1001–1006
An installment of the Rational Clinical Examination Abstract series:
This is a Rational Clinical Examination abstract, a regular feature of the Annals' Evidence-Based Emergency Medicine (EBEM) series. Each features an abstract of a Rational Clinical Examination review from the Journal of the American Medical Association and a commentary by an emergency physician knowledgeable in the subject area. The source for this Rational Clinical Examination abstract is: Salkind AR, Cuddy PG, Foxworth JW. Is this patient allergic to penicillin: an evidence-based analysis. 2001;85(19):2498-05. The Annals EBEM editors assisted in the preparation of the abstract of this Rational Clinical Examination abstract.
PII: S0196-0644(09)01509-1
doi:10.1016/j.annemergmed.2009.08.025
© 2010 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.
