DRUG ALLERGIES IN THE SURGICAL POPULATION

Many patients claim to have drug allergies. However the signs and symp toms of ''allergic reactions'' are seldom documented and the drug alle rgies are rarely properly assessed. The goal of this study was to dete rmine the incidence of claimed ''drug allergies'' in a surgical popula tion. After obtaining institutional approval, the study was carried ou t at five hospitals affiliated with Dalhousie University. Patients wer e interviewed by the investigators during the preoperative anaesthetic evaluation over six months and all signs and symptoms of drug reactio ns were recorded. The validity of the claimed allergy was based on the history. The allergies were assigned to one of three groups: (I) High probability of an allergic reaction: one or more of the signs and sym ptoms typical of an immunological reaction, with or without a family h istory, or a history of atopy; (ii) Low probability of an allergic rea ction: signs and symptoms of the reaction were predictable reactions o r side effects of the drug, without the occurrence of reactions mentio ned above; or (iii) Unknown status: no information concerning the reac tion of history was available. Of 1818 adult and paediatric patients ( 914 female/904 male) interviewed, 511 (28. 1%) claimed to have one or more drug allergies (a total of 671 allergies). More women than men cl aimed to have drug allergies (60.3% vs 39.7%) and there was a positive correlation between age, number of medic ations and reported drug all ergies. Antibiotics (50%), opioids; (27%), non-steroidal anti-inflamma tory agents (10%), and sedatives (5%) accounted for 92% of all claimed drug allergies. Overall, 50% of claimed allergies had a high probabil ity of true allergic reactions. The majority of antibiotics (75%) were associated with a high probability for true allergic, reactions, but most of the other drug classes, such as opioids (83%), NSAIDs (64%) an d sedatives (67%), were associated with a low probability for true all ergic reactions. Our findings suggest a serious problem in the ''label ling'' of our patients as having drug allergies. Patients and health c are personnel should be educated in the differentiation between predic table adverse drug reactions and true allergic drug reactions.