Background: The effective treatment of COVID-19 remains unclear. We reported successful use of high-dose intravenous immunoglobulin (IVIg) in cases of severe COVID-19, but evidence for such treatment is still lacking.Methods: A multi-center retrospective study was conducted to evaluate the effectiveness of IVIg administered within two weeks of disease onset at a total dose of 2 g/kg body weight, in addition to standard care. The primary endpoint was 28-day mortality. Efficacy of high-dose IVIg was assessed by using the Cox proportional hazards regression model and the Kaplan-Meier curve adjusted by propensity score-matched (PSM) and inverse probability of treatment weighting (IPTW) analysis.Results: Overall, 26 patients who received high-dose IVIg with standard therapy and 79 patients who received standard therapy only were enrolled in this study. The IVIg group was associated with a lower 28-day mortality rate and less time to normalization of inflammatory markers including IL-6, IL-10 and ferritin compared with the control. The adjusted HR of 28-day mortality in high-dose IVIg group was 0.28 (95%CI 0.06-1.10, p=0.061) in propensity score-matched (PSM) analysis, and 0.24 (95%CI 0.06-0.99, p<0.001) in inverse probability of treatment weighting (IPTW) adjustment. In subgroup analysis, patients with no comorbidities or treated in the first week of disease were associated with more benefit from high-dose IVIg.Conclusions: High-dose IVIg administered in severe COVID-19 patients within 14 days of onset was linked to reduced 28-day mortality, more prominent with those having no comorbidities or treated at earlier stage.Funding Statement: None.Declaration of Interests: All authors declared no competing financial interests.Ethics Approval Statement: The study protocol was approved by the institutional ethics board of Peking Union Medical College Hospital (PUMCH, No. ZS-2299, Feb 6, 2020), and all participants provided written consent for participating this study.
High-Dose Intravenous Immunoglobulin in Severe Coronavirus Disease 2019: A Multicenter Retrospective Study in China