Prediction of clinical requirement of tocilizumab injection in COVID-19 patients with high chest CT severity score - A retrospective analysis

Introduction: The on-going Corona-Virus Disease 2019 (COVID-19) pandemic has spread rapidly across the globe. Tocilizumab is a recombinant monoclonal antibody to Interleukin-6 (IL-6) receptor. An increasing number of studies across the world is reporting the use of tocilizumab in treating COVID-19 patients or at risk of developing cytokine storm. Apart from clinical and laboratory parameters, High Resolution Computed Tomographic (HRCT) chest scan is a promising tool to identify patients very early in the course of COVID-19 disease. Aim: The purpose of this retrospective research study is to find whether high chest CT Severity Score (CTSS) on HRCT thorax scan predict the clinical requirement of tocilizumab injection in COVID-19 patients. Materials and Methods: In this retrospective study, during the period from May 2020 to July, 2020, 250 patients with confirmed Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) diagnosed of COVID-19 on first or repeat sample and who also underwent HRCT scan of the chest, were assigned chest CTSS. From data obtained, patients were categorised into two groups based on mild and severe CTSS. Patients with higher CTSS have a higher future possibility of developing the cytokine storm and hence the requirement of tocilizumab can be reliably predicted. All statistical analysis was performed in IBM SPSS version 20. Results: Out of a total of 250 patients, 72 patients were given tocilizumab injection. The average CTSS was 29.8±6.38 in the tocilizumab injection group. Only 8% of patients with mild CTSS received tocilizumab injection while 60% of patients with severe CTSS received tocilizumab injection (p<0.001). Out of 72 patients who received tocilizumab injection, 16.7% had mild CTSS while 83.3% had severe CTSS (p<0.001). Average values of inflammatory markers like CRP, D-Dimer, Ferritin, LDH, and IL-6;were significantly higher in severe CTSS and tocilizumab group (p<0.001). Conclusion: CTSS may be used as a new decisive tool in triaging in-hospital COVID-19 patients. Categorising patients in mild and severe CTSS early in the disease course, even before the marked worsening of laboratory parameters and development of cytokine storm may help initiate early treatment and thereby save many lives.