At the moment, there are no approved predictive markers of immune adverse events (irAES) induced by immune checkpoint inhibitors (ICIs) and the treatment efficacy. The early stages of irAES have some similarities with adjuvant-induced autoimmune/pro-inflammatory syndrome (ASIA). This study aims to assess the predictive possibility of using the “ASIA questionnaire” in patients on immune checkpoint inhibitor therapy in comparison with determination of PD-L1 expression to predict the risk of irAES development and therapy efficacy. We examined patients (n = 91) being treated for solid tumors. The signs of ASIA were found in 74% (66/91), while ASIA syndrome was diagnosed in 54% of cases (49/91). No statistically significant difference in the frequency of ICI-dependent complication development regarding the presence of previous ASIA clinical manifestations, hereditary factors, sex, different trigger factors was found. Index based on combination of PD-L1 determination and ASIA index was created. With reference > 2.5 units, the disease control rate (DCR) could be predicted with sensitivity 100.0% and specificity 70.00%, p = 0.007. The study did not reveal the diagnostic value of ASIA questionnaire to assess the risk of adverse events; however, in early stages, the development of ASIA symptoms diagnosed with the questionnaire in complex with PD-L1 expression allowed to predict a treatment efficacy.