The association between tocilizumab therapy and the development of thrombosis in critically ill patients with COVID-19: a multicenter, cohort study

Abstract The use of tocilizumab for the management of COVID-19 emerged since it modulates inflammatory markers by blocking interleukin 6 receptors. Concerns regarding higher thrombosis risk while using tocilizumab were raised in the literature. The aim of this study is to investigate the association between tocilizumab therapy and the development of thromboembolic events in critically ill COVID-19 patients. A propensity score-matched, multicenter cohort study for critically ill adult patients with COVID-19. Eligible patients admitted to ICU between March 2020 and July 2021 were categorized into two sub-cohorts based on tocilizumab use within 24 h of ICU admission. The primary endpoint was to assess the incidence of all thrombosis cases during ICU stay. The secondary endpoints were 30-day mortality, in-hospital mortality, and the highest coagulation parameters follow-up (i.e., D-dimer, Fibrinogen) during the stay. Propensity score matching (1:2 ratio) was based on nine matching covariates. Among a total of 867 eligible patients, 453 patients were matched (1:2 ratio) using propensity scores. The thrombosis events were not statistically different between the two groups in crude analysis (6.8% vs. 7.7%; p-value = 0.71) and regression analysis [OR 0.83, 95% CI (0.385, 1.786)]. Peak D-dimer levels did not change significantly when the patient received tocilizumab (beta coefficient (95% CI): 0.19 (− 0.08, 0.47)), while there was a significant reduction in fibrinogen levels during ICU stay (beta coefficient (95% CI): − 0.15 (− 0.28, − 0.02)). On the other hand, the 30-day and in-hospital mortality were significantly lower in tocilizumab-treated patients (HR 0.57, 95% CI (0.37, 0.87), [HR 0.67, 95% CI (0.46, 0.98), respectively). The use of tocilizumab in critically ill patients with COVID-19 was not associated with higher thrombosis events or peak D-dimer levels. On the other hand, fibrinogen levels, 30-day and in-hospital mortality were significantly lower in the tocilizumab group. Further randomized controlled trials are needed to confirm our findings.