Objectives The evidence for tocilizumab in the treatment of COVID-19 is contradictory, with some clinical trials showing benefits in regard to progression to mechanical ventilation (MV) and/or mortality. The aim of this study is to evaluate in real clinical practice the effectiveness of tocilizumab in treating COVID-19 and to identify prognostic factors for patient outcomes.

Methods This was an observational, retrospective study of COVID-19 patients treated with tocilizumab between March 2020 and February 2021 in a tertiary hospital. Variables were demographics, comorbidities, vital signs, analytical parameters, COVID-19 treatment, progression to MV, intensive care unit (ICU) admission, hospital stay, and mortality.

Results A total of 685 patients (64.7% men, median 68 years) were included. Overall mortality was 23.4% (14.2% in the first 14 days post-tocilizumab) and 93.3% in patients with MV and/or in the ICU at 14 days post-tocilizumab. In addition, 61.5% of discharges occurred during the same period. In patients who died, statistically significant differences were observed in the baseline analytical parameters of C-reactive protein (CRP), D-dimer and higher lactate dehydrogenase (LDH) (p<0.05).

Conclusions In most patients the clinical results of tocilizumab were observed at 14 days post-administration and could benefit from earlier administration of treatment. Baseline levels of CRP, D-dimer and LDH could be prognostic factors for the evolution of the COVID-19 patient.