Treatments for Multi-System Inflammatory Syndrome in Children — Discharge, Fever and Second-Line Therapies

Background: Scarce evidence exists about the best treatment for multi-system inflammatory syndrome (MIS-C). We analysed the effects of steroids, intravenous immunoglobulin (IVig), and their combination on the probability of discharge over time, probability of switching to second-line treatment over time, and persistent fever after 2 days of treatment. Methods: We did a retrospective study to investigate the effect of treatments (IVig plus steroids, steroids alone or IVig alone) on children with MIS-C from 1 March to 1 June 2021. We estimated the time-to-event probability using a Cox model weighted by propensity score to balance the baseline characteristics. Findings: 30/132 (22·7%) patients were initially treated with steroids alone, 29/132 (21·9%) with IVig alone, and 73/132 (55%) with IVIG plus steroids. The probability of early discharge was higher with IVig than with IVig plus steroids (hazard ratio [HR] 1·65, 95% CI 1·11–2·45, p=0·013), but with a higher probability of needing second-line therapy versus IVig plus steroids (HR 3·05, 95% CI 1·12-8·25, p=0·028). Patients on steroids had a lower probability of persistent fever after 2 days of treatment (odds ratio [OR] 0·55, 95% CI, 0·28–1·05, p=0·081) versus patients on IVig plus steroids, and those on the combination had a lower probability versus IVig alone (OR 0·21, 95% CI, 0·09–0·46, p=0·0001). Interpretation: The benefits of each approach may vary depending on the outcome assessed. IVig seemed to increase the probability of earlier discharge over time but also of needing second-line treatment over time. Steroids seemed to reduce persistent fever after 2 days of treatment, and combination therapy reduced the need for escalating treatment. Funding Information: Instituto Salud Carlos III, PI20/00095, SERMAS-Fundacion para la Investigacion Biomedica Hospital 12 de Octubre, Spanish Society of Paediatrics, SERMAS-Fundacion para la Investigacion Biomedica Hospitales Infanta Sofia y Henares, Fundacion Universidad Europea de Madrid. Declaration of Interests: No conflicts of interest. Ethics Approval Statement: The study was approved by the Ethics Committee of Hospital 12 de Octubre, Madrid (code 20/101), and other participating hospitals. Participants were enrolled after signed or verbal consent from parents/guardians and by the consent of patients older than 12 years.