Comparative evaluation of autologous serum skin test and autologous plasma skin test in chronic urticaria

Objective: To compare autologous serum skin test (ASST) and autologous plasma skin test (APST) in the diagnosis of autoimmune urticaria Patients and methods: A prospective study was done in patients with chronic urticaria. Autologous plasma and serum skin tests were performed in all patients who were meeting the inclusion and exclusion criteria and readings were taken at the end of 30 minutes. Results: Fifty-nine patients (Males-25 and Females-34) were enrolled in the study. ASST was positive in 24 (40.7%) and APST was positive in 27 (45.8%) out of 59 patients. 20 (33.9%) were positive to both ASST and APST, 28 (47.5%) were negative to both ASST and APST. Conclusion: ASST and APST are two simple, inexpensive and easy to do in-office procedures which can be used to diagnose autoimmune urticaria. APST was slightly superior to ASST in diagnosing autoimmune urticarial in our study. Although many patients showed positivity to both tests, significant numbers of patients were positive to only one test. We thus recommend the performance of both ASST and APST in all patients of chronic urticaria to detect those patients of chronic autoimmune urticaria.