IL6 and COVID-19: Third, the purpose of this meta-analysis was to explore the correlation between concentrations of three cytokines, IL-6, ferritin and LDH, and the occurrence of VTE in patients with COVID-19, and thus the patients included were varying in ages and severity in order to observe and analyze the problem in a wider, more detailed and deeper way, and therefore it was unavoidable that some degree of heterogeneity appeared.