The predictive value of skin testing in the diagnosis of local anesthetic allergy

Local anesthetics are commonly used medications and can result in adverse reactions. The diagnostic workup of local anesthetic reactions remains controversial. This study was designed to determine the effectiveness of skin testing for local anesthetic allergy evaluation. A retrospective chart review was performed on patients undergoing local anesthetic skin testing. Patients were included if they underwent prick and intradermal skin testing followed by incremental subcutaneous challenge. Charts were further systematically reviewed to evaluate response to local anesthetics in the clinical setting after open subcutaneous challenge. One hundred seventy-eight patients underwent 227 local anesthetic skin tests. Two hundred twenty (97%) of the skin tests were negative. Of the negative skin tests results, 214 (97%) had negative challenge or probable non-IgE-mediated events during challenge. Three patients with six negative skin tests had a local reaction during the open subcutaneous challenge. Seven skin tests on five patients met the criteria for a positive skin test with local anesthetics. One patient had an equivocal local skin reaction with subcutaneous challenge without systemic effects. Three patients had a negative subcutaneous challenge and one patient did not undergo a challenge. Ninety-eight percent of patients receiving local anesthetics in the clinical setting after open subcutaneous challenge tolerated the medications. The negative predictive value of the local anesthetic skin test was 97% with few positive skin tests. Positive local anesthetic skin tests are uncommon and the local anesthetic skin tests have an excellent negative predictive value. Additional study with skin test - only protocols is warranted.