Beneficial of adding Tocilizumab to standard care in critical forms of Covid-19 pneumonia: Study on paired series.

Introduction: Tocilizumab (TCZ), a humanized monoclonal antibody directed against interleukin-6 (IL-6) receptors, has been tried in various studies as a Covid-19 therapy with controversial results.
Aim: To evaluate the effectiveness of adding TCZ to standard care (SC) in critical Covid-19 patients.
Methods: it was designed retrospectively as a comparative study on two paired series of critical patients affected with Covid-19: the 1st group received TCZ plus SC versus a 2nd group which received only SC. The matching criteria were age, sex and severity score and the matching was based on the propensity score matching (PSM) by the nearest neighbor. Outcomes were: survival, mechanical ventilation (MV) and nosocomial infections.
Results: Ninety patients were included by pairing estimated successful (PSM > 0.5 in more than 50% in each group for all matching criteria). 55.5% of SC group progressed to stage 3-acute respiratory distress syndrome (ARDS) versus 31% of TCZ+SC patients (p=0.03). No effect of TCZ was found on mortality (49% in each group, p=1) nor on MV use (p=0.67). ICU stay was more prolonged in TCZ+SC group (16 versus 8 days, p<10-3). The administration of TCZ induced a significant decrease in CRP but not changed the IL-6 dosage. Nosocomial infections occurred in 18 (40%) of TCZ+SC group comparatively to 15 (33,5%) of SC group, p=0.66.
Conclusion: Tocilizumab reduced the risk of progression to severe ARDS probably due to its immune-modulating properties. But no beneficial effect was found on survival or on the use of ventilation.