Surveillance of adverse effects of Tocilizumab for COVID-19

Background: Tocilizumab (TCZ) is a new therapeutic alternative for severe cases of COVID-19 pneumonia. Aim: To evaluate the cumulative incidence (CI) of suspected adverse drug reactions (ADR) from TCZ in adult patients with COVID-19. Material and Methods: An active pharmacological surveillance protocol was carried out in patients older than 18 years old, who received at least one dose of TCZ between May and August 2020 at a clinical hospital. Non-infectious ADRs were categorized according to the Common Terminology Criteria for Adverse Events and the development of infection was classified as present or absent. Causality and preventability of ADRs were determined with the Naranjo Algorithm and the modified Schumock & Thornton criteria, respectively. Results: The CI of ADRs caused by TCZ was 69.6% (95% confidence intervals (CI): 63.5-76.6). A rise in alanine and aspartate aminotransferases and the development of infections were the most frequent adverse events. Seventy-four percent were considered mild in severity. Sixty two percent of suspected non-infectious ADRs were classified as probable and all the infectious events as Possible. Of the ADRs observed, 33% were preventable. Conclusions: The occurrence of ADRs after the use of TCZ is frequent, of mild severity, and in one third of the cases, preventable. We suggest monitoring blood count, liver function tests and ruling out infection prior to TCZ administration.