LAUSR

DEAR EDITOR, the diagnosis of autoimmune chronic urticaria (AIU) is difficult. The autologous serum skin test (ASST) is a screening method to diagnose AIU and was first used by Grattan et al. and standardized by Sabroe et al. One major limitation of ASST is that positivity can refer not just to the presence of functional autoantibodies against FceRIa or IgE, but other as-yet-unidentified serum factors. Besides the advantages of ASST, which are its fast and easy implementation and its cost, as its positivity alone cannot define AIU, other methods are needed to confirm the diagnosis of AIU. Some study groups suggested immunoassay methods [immunoblot, enzyme-linked immunosorbent assay (ELISA)] to detect autoantibodies, but these tests are time-consuming, cannot differentiate between functional and nonfunctional autoantibodies, and may also yield false-positive and -negative results. Functional tests, such as the basophil histamine release assay (BHRA) and the basophil CD63 assay, have the best sensitivity and specificity in the diagnosis of AIU. However, both the BHRA and the basophil CD63 assay are difficult to perform, time-consuming and expensive, and several laboratories do not have suitable conditions to use them in, which make these tests unsuitable for clinical practice. The aim of our study was to improve the diagnostic value of the ASST by keeping the method but adding a combination of clinical/anamnestic and laboratory data to it. Fifty-five patients with chronic spontaneous urticaria (CSU) were selected. According to the guideline, patients whose urticarial symptoms suggested autoinflammatory disease, urticarial vasculitis, chronic inducible urticaria, hereditary angioedema or angiotensin-converting enzyme inhibitorinduced angioedema were excluded from the study. Antihistamine treatment was stopped at least 4 days before, and corticosteroid or immunosuppressive therapy at least 2 months before serum samples were collected for investigation and analysis. A detailed questionnaire was filled out by the patients to collect anamnestic/clinical data (Table 1). Laboratory tests (antithyroglobulin antibody, antithyroid peroxidase antibody) and the ASST were also performed. When the study was initiated the Breneman score was used to determine the severity of urticaria. With the Breneman score the number of lesions, number of separate episodes, average size and duration of lesions, and pruritus can be rated from 0 to 3, with a maximum score of 15. A result of > 10 points was