391 Description of Drug Allergy Study Conducted in a Teaching Hospital between October 2007 and March 2011

BACKGROUND: The World Allergy Organization (WAO) in 2003 defined ‘drug allergy’ as an immunologically mediated drug hypersensitivity reaction. The mechanism of drug allergy may be either IgE or non-IgE mediated. The true incidence of drug allergy is not known. There are only few studies/datasets using standardized clinical questionnaires and validated in vivo or in vitro tests to confirm the diagnosis of drug allergy. Here we have analyzed the obtained results of in vivo test in suspected drug allergy patients. METHODS: Data from the Centre of Allergies of the Clinical Hospital of the Universidad de Chile between the months of October 2007 and March 2011 was obtained. The information of the protocols of drug executed, by defining as Protocol the study of a probable allergy by 2 or more procedures, which can be: Prick Test, intradermal reaction, specific IgE and/or Test Patch. RESULTS: For a total of 126 drug protocols, 25% of them were trivírica vaccine, 24% β-lactams, 21% local anaesthetics and 10% to general anesthesia (inductors, muscle relaxants and Latex). Of the total of patients undergoing protocols the most of them were women, there is no clear difference between the number of children and adults. The temporal distribution of protocols was stable between the months of October 2007 and March 2009 (15 protocols/semester), to then become variable, reaching values between 10 and 29 every 6 months. Of total protocols, 30.1% were positive; only one patient presented a mild adverse reaction (local welt). The β-lactams being most often the positive drugs. Protocols involving pethidine 100% was positive, diclofenac 33%, dipyrone, ketoprofen and hydrocortisone each one 25%. The most accomplished protocol was trivírica vaccine, resulting in 100% negative. Of all negative protocols 58% went to provocation, resulting in a 8% positive, including one provocation to the trívirica vaccine. CONCLUSIONS: Methodologicall study is very important for a possible drug allergy, because history is not enough to certify the diagnosis. To do a provocation test to a negative protocol is crucial.