History of penicillin allergy and referral for skin testing: evaluation of a pediatric penicillin allergy testing program.
INTRODUCTION: Penicillin allergy, commonly reported in children, leads to use of more expensive, broad-spectrum drugs. The results and effectiveness of a skin testing program for immediate hypersensitivity to penicillin in children were studied. METHODS: Children seen at the IWK Health Centre in Halifax between 1986 and 2000 with a history of suspected penicillin allergy were referred by their family physician or pediatrician. Two-stage skin testing (scratch, intradermal) of benzylpenicilloyl-polylysin and penicillin G sodium, with histamine and saline as positive and negative controls, was carried out. If the test results were negative, an oral challenge was conducted and the child observed for 60 minutes. If no adverse reaction was noted, a letter was sent to the referring physician and to Health Records at the IWK Health Centre, indicating that warning labels should be removed from the chart. RESULTS: Of 72 children tested, 32% described their past cutaneous eruption as hives and 68% had other rashes; 96% of rashes were generalized. The mean age at the time of the suspected penicillin allergy was 4.4 years; it was 7.4 years at the time of testing. There was no positive response to the scratch testing, but 4% of children had a positive response to intradermal testing. No adverse responses to oral challenge were observed. Letters confirming negative status were not received in 4% (3 of 69) cases, resulting in ongoing avoidance of penicillins and falsely labelling of the child as penicillin allergic. CONCLUSIONS: In this referral setting, true penicillin allergy was uncommon, suggesting that many children are incorrectly labelled as penicillin-allergic. Communication of test results to family and care providers and health records administration must be effective if testing is to affect prescribing behaviour.