Background

Respiratory failure and death are the leading causes of severe Coronavirus disease 2019 (COVID-19). Hyper-inflammation and cytokine storm cause lung damage. This study aimed to compare the low-dose and high-dose effects of tocilizumab, an IL-6 receptor antagonist.

Method

Patients with severe pneumonia and hyper-inflammation signs due to COVID-19 were included in this retrospective study. Patients receiving tocilizumab < 200 mg intravenously were classified as the low-dose group, and receiving ≥ 200 mg as the high-dose group, and those not treated with tocilizumab as the control group. Demographic and clinical data of patients who died and survived in both low-high dose and control patients were compared. According to symptom day and radiological infiltration, patients with tocilizumab were also evaluated in two groups as early and late periods at tocilizumab administration time.

Results

A total of 160 patients were included in the study; 70 were treated with a low dose and 50 with high dose tocilizumab. Forty patients were in the control group. Age, comorbidity, and clinical features were similar in the control, low-dose tocilizumab, and high-dose tocilizumab groups. The mortality rate (12.9%, 30.0%, 37.5, p = 0.008) was less in the low-dose tocilizumab group. The secondary infection rate was higher in the high-dose group than in the low-dose tocilizumab and control groups (44.0%, 10.0%, 10.0%, p<0.001). Distinguishing between those patients who died and survived, age (OR: 1.1589, p<0.001), higher APACHE II scores (OR: 1.225, p=0.001), and needs for non-invasive mechanical ventilation (OR: 14.469, p<0.001) were the most critical risk factors. Low-dose tocilizumab was associated with a lower mortality rate (OR: 0.244, p=0.012).

Conclusion

The use of tocilizumab at a low dose is associated with lower secondary infections and mortality.