Early Fall in C-Reactive Protein (CRP) Level Predicts Response to Tocilizumab in Rapidly Progressing COVID-19: Experience in a Single-Arm Pakistani Center

Introduction There are conflicting studies regarding the efficacy of tocilizumab use in coronavirus disease 2019 (COVID-19) disease. There is a special need to identify the parameters that could predict its response in early COVID-19 disease. Objective To report our experience with tocilizumab and correlate the magnitude of fall in c-reactive protein (CRP) as a predictor of its response to treatment in early COVID-19 disease. Methods All confirmed COVID-19 cases admitted to a tertiary healthcare hospital in Peshawar Pakistan, receiving ≥1 dose of intravenous tocilizumab, between March and September 2020 were included. Relevant clinical data of the patients were recorded and further divided into two categories based on the relative fall in CRP levels, 48 hours after tocilizumab administration. Adequate response (≥50% fall from baseline CRP), primary outcomes (fall in oxygen requirement and inflammatory biomarkers), and secondary outcome (all-cause mortality at day 28) were recorded. All outcomes were compared based on falls in CRP levels. Results A total of 27 patients were included. Males were 24 (88.8%) while females were three (11.1%). The mean age was 60.9±11.6 years. The mean day of illness at the time of tocilizumab administration was 4.26±3 days. After 48 hours of tocilizumab administration, 17 (62.9%) patients showed clinical improvement, with the mean SaO(2)/FiO(2 )ratio prior to treatment significantly increased (p<0.01). A significant reduction in CRP and ferritin levels was seen post-treatment (p <0.01 and p<0.01, respectively). Twenty (74.1%) patients demonstrated adequate response to tocilizumab while seven (25.9%) showed an inadequate response. Patients with adequate response had higher chances of improvement in oxygenation and lower in-hospital mortality (p-value 0.009 and 0.020, respectively). Conclusions Tocilizumab shows clinical improvement in a vast majority of patients. Being an early and sensitive predictor, a fall of ≥50% in CRP at 48 hours can be used to predict the overall response to tocilizumab as a guide to treatment.