TY - JOUR T1 - Correspondence on ‘Historically controlled comparison of glucocorticoids with or without tocilizumab versus supportive care only in patients with COVID-19-associated cytokine storm syndrome: results of the CHIC study’ JF - Annals of the Rheumatic Diseases JO - Ann Rheum Dis DO - 10.1136/annrheumdis-2021-219986 SP - annrheumdis-2021-219986 AU - Pierre Charles Y1 - 2021/02/13 UR - http://ard.bmj.com/content/early/2021/02/14/annrheumdis-2021-219986.abstract N2 - I was surprised when I read your web page promoting the study ‘Historically controlled comparison of glucocorticoids with or without tocilizumab versus supportive care only in patients with COVID-19-associated cytokine storm syndrome: results of the CHIC study’.1 The methodology of this study (comparison of a treatment with a historical control) is known to lead to major biases. The results were positive, consistent with … ER -