Anti-interleukin-6 therapies for Covid-19: A systematic review, critical appraisal and meta-analysis.

BACKGROUND . Coronavirus disease 2019 (Covid-19) has emerged as a pandemic by end-January 2020. Of the infected patients, 10%-15% may develop severe or critical illness. So far, no definite treatment is available for Covid-19. Cytokine release syndrome may underlie the pathogenesis of severe and critical disease. Anti-interleukin (IL)-6 therapies are being tried to improve clinical outcomes. METHODS . We did a systematic review to identify the available literature on anti-IL-6 therapies in the treatment of Covid-19 and used the GRADE method to assess the quality of evidence. RESULTS . Four case series and 10 case reports were identified. On critical assessment, we found that these studies reported some beneficial effect of anti-IL-6 therapy, but all the studies had a high risk of bias. The pooled estimate showed that 42% of patients improved but with a very wide confidence interval (CI) (95% CI 1%-91%) and substantial heterogeneity (I2 = 95%). The overall quality of evidence was graded as 'very low'. CONCLUSIONS . Although promising, anti-IL-6 therapy for Covid-19 needs to be tested in randomized controlled trials to provide robust evidence.