Autologous serum skin test vs autologous plasma skin test in patients with chronic urticaria: evaluation of reproducibility, sensitivity and specificity and relationship with disease activity, quality of life and anti-thyroid antibodies.

Recent concerns have arisen about the specificity and interpretation of the autologous serum skin test (ASST), suggesting that ASST might produce false-positive results, and proposing the use of autologous plasma (APST) instead for intradermal testing in autoreactive urticaria. We investigated autoreactivity to autologous plasma and compared the results for reproducibility, sensitivity, specificity and accuracy and evaluated their association with quality of life and anti-TPO antibodies. 70 adults with chronic spontaneous urticaria (CU) and 62 controls underwent testing with ASST and APST and the tests were repeated two days after the first visit. Blood tests measured anti-TPO levels. Disease activity was assessed by urticaria activity score (UAS-7) and quality of life impairment was assessed by DLQI and CU-Q(2)oL. There were no statistically significant differences between ASST (+) and ASST (-) and also APST (+) and APST (-) patients with regard to disease duration, anti-TPO antibodies, urticaria activity scores, DLQI scores and CU-Q(2)oL scores. The results of first ASST and APST were well correlated with the results of second ASST and APST. The specificity of the two tests was similar, while ASST had a higher sensitivity and accuracy. Our results showed that there is no need to use autologous plasma instead of autologous serum for intradermal testing in CU.