Objective: To compare the effects of interleukin 6 receptor blockers, tocilizumab and sarilumab, with or without corticosteroids, on mortality in patients with covid-19.

Design: Systematic review and network meta-analysis.

Data sources: World Health Organization covid-19 database, a comprehensive multilingual source of global covid-19 literature, and two prospective meta-analyses (up to 9 June 2021).

Review methods: Trials in which people with suspected, probable, or confirmed covid-19 were randomised to interleukin 6 receptor blockers (with or without corticosteroids), corticosteroids, placebo, or standard care. The analysis used a bayesian framework and assessed the certainty of evidence using the GRADE approach. Results from the fixed effect meta-analysis were used for the primary analysis.

Results: Of 45 eligible trials (20 650 patients) identified, 36 (19 350 patients) could be included in the network meta-analysis. Of 36 trials, 27 were at high risk of bias, primarily due to lack of blinding. Tocilizumab, in combination with corticosteroids, suggested a reduction in the risk of death compared with corticosteroids alone (odds ratio 0.79, 95% credible interval 0.70 to 0.88; 35 fewer deaths per 1000 people, 95% credible interval 52 fewer to 18 fewer per 1000; moderate certainty of evidence), as did sarilumab in combination with corticosteroids, compared with corticosteroids alone (0.73, 0.58 to 0.92; 43 fewer per 1000, 73 fewer to 12 fewer; low certainty). Tocilizumab and sarilumab, each in combination with corticosteroids, appeared to have similar effects on mortality when compared with each other (1.07, 0.86 to 1.34; eight more per 1000, 20 fewer to 35 more; low certainty). The effects of tocilizumab (1.12, 0.91 to 1.38; 20 more per 1000, 16 fewer to 59 more; low certainty) and sarilumab (1.07, 0.81 to 1.40; 11 more per 1000, 38 fewer to 55 more; low certainty), when used alone, suggested an increase in the risk of death.

Conclusion: These findings suggest that in patients with severe or critical covid-19, tocilizumab, in combination with corticosteroids, probably reduces mortality, and that sarilumab, in combination with corticosteroids, might also reduce mortality. Tocilizumab and sarilumab, in combination with corticosteroids, could have similar effectiveness. Tocilizumab and sarilumab, when used alone, might not be beneficial.