IS REFERRING PATIENTS WITH A POSITIVE HISTORY OF ALLERGIC DRUG REACTIONS OR ATOPY FOR ALLERGY TESTING TO LOCAL ANESTHETICS JUSTIFIED?

Although no more than 1% of adverse reactions to local anesthetics (LA) are thought to be immunologically mediated, many patients continue to be referred to allergy clinics for allergy workup. We evaluated the impact of a history of drug hypersensitivity or atopy on results of allergy testing to LA, with the oim of determining the appropriateness of allergy testing to LA in such patients. We retrospectively analyzed medical records of 772 consecutive patients referred for allergy testing to LA in a 9-year period (1996-2005). Intradermal tests with diluted (1:10) LA were performed to identify patients at risk for immunoglobulin E (IgE)-mediated hypersensitivity reaction. The odds for being test-positive were calculated with regard to the defined risk factors (atopy, history of adverse reactions to LA or other drugs, underlying autoimmune disease). Eleven of 112 patients (9.8%) tested positive for allergy to LA. Atopy, history of adverse reactions to LA or other drugs and underlying autoimmune disease did not increase the odds for being test-positive. The prevalence of multiple drug hypersensitivity, IgE values and eosinophil count were not significantly higher among the patients who tested positive as compared to the patients who tested negative. According to our data, allergy testing to LA is not justified in patients with atopy or histories of adverse drug reactions other than to LA. Further studies using validated methods of allergy testing to LA coupled with analysis of defined risk factors ore needed to definitively establish the indications for referral of patients for allergy testing to LA.