The randomised controlled RECOVERY trial1 has met its primary endpoint of reduced 28-day mortality. We congratulate the RECOVERY Collaborative Group for this excellent study. However, the mortality at day 28 was up to 31% in the tocilizumab group and was higher than the results of other published randomised controlled trials.2 The pathophysiology underlying COVID-19 is characterised by SARS-CoV-2 viral infection-induced inflammatory response, cell death, and microvascular thrombosis. Thrombosis appears to be common in patients with COVID-19 pneumonia and could also be responsible for multiorgan failure in patients who are critically ill.3 Larger studies have shown that patients with COVID-19 are at increased risk of thrombosis and that 29·4% of patients in the intensive care unit had a thrombotic event (13·6% venous and 18·6% arterial).4 Furthermore, the thrombotic event is independently associated with mortality of COVID-19 patients.4
ClinicalTrials.gov records thrombotic events including acute pulmonary embolism, deep vein thrombosis, ischaemic stroke, myocardial infarction, or systemic arterial embolism as the prespecified outcome of this study protocol. However, the RECOVERY Collaborative Group omitted such important outcomes from the published results without any clear explanation.
There is clinical evidence to suggest tocilizumab therapy in patients with COVID-19 may be associated with thrombotic events.5 To better analyse the efficacy and safety of tocilizumab, the RECOVERY Collaborative Group should specify the number of thrombotic or thromboembolic events observed in their study and specifically detail the proportion of patients receiving therapeutic anticoagulation in both groups. These results will better inform clinical practice on the use of tocilizumab for patients with COVID-19.
© 2021 Steve Parsons/PA Wire/Bloomberg via Getty Images
CY is a former postdoctoral fellow at the University Health Network. We declare no competing interests.
References
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