Autologous serum and plasma skin tests in chronic spontaneous urticaria: A reappraisal

Aim: The objective of this study was to assess autologous serum skin test (ASST) vs autologous plasma skin test (APST) response in chronic spontaneous urticaria (CSU) patients and study the significance of intensity of positive responses in relation to clinicoepidemiological parameters. Materials and Methods: One hundred CSU patients and 100 age and sex-matched controls were recruited. The demographic and clinical features were recorded in all patients and routine investigations were performed. ASST and APST tests were performed as per the standard guidelines. Results: The mean duration of illness was 4.85 ± 5.07 years, 90% patients were APST (+), 68% ASST (+), and 22 patients were only APST (+). Positive predictive value (PPV) of ASST and APST was 90.7% and 95.7%, respectively. A significant inverse association was seen between thyroid status and serum IgE levels with APST and ASST positivity. Conclusion: APST appears to have better PPV and high intensity of positive response on autologous tests, and correlates with ANA positivity and angioedema