Short-term Outcomes of Corticosteroid Monotherapy in Multisystem Inflammatory Syndrome in Children.

Importance: Optimal agents and duration of primary treatment for multisystem inflammatory syndrome in children (MIS-C) remain unclear.

Objective: To compare short-term patient outcomes based on initial treatment with corticosteroids, intravenous immunoglobulin (IVIG), or both.

Design, Setting, And Participants: This retrospective cohort study included patients in a tertiary-care pediatric hospital system who had MIS-C per the Centers for Disease Control and Prevention case definition during the period March 2020 to February 2021.

Exposures: Immunomodulatory therapy within the first 24 hours (patients in the intensive care unit [ICU]) or 48 hours (non-ICU patients): corticosteroids alone, IVIG alone, and IVIG plus corticosteroids.

Main Outcomes And Measures: Primary outcome was failure of initial therapy, defined as therapy escalation due to fever or worsening or lack of improvement of laboratory, cardiac, or noncardiac clinical factors after 24 hours (ICU patients) or 48 hours (non-ICU patients) from time of therapy initiation, per clinician assessment. Secondary outcomes included presence of complications, cardiovascular outcomes, fever duration, length of hospital and ICU stays, corticosteroid use duration, and need for readmission.

Results: Among 228 eligible patients, 215 patients were included in the univariate analysis; median age was 8 years, and 135 (62.8%) were boys. There were 69 patients in the corticosteroids group, 31 patients in the IVIG group, and 115 patients in the IVIG plus corticosteroids group. Patients in the corticosteroids group had milder disease at presentation. After propensity score weighting including 179 patients (68 in the corticosteroids group and 111 in the IVIG plus corticosteroids group), rates of initial treatment failure were similar between groups. Among patients whose initial treatment failed, treatment failure in the IVIG plus corticosteroids group was more likely to be based on laboratory parameters (odds ratio [OR], 1.96; 95% CI, 1.07-3.60) and less likely to be based on cardiovascular markers (OR, 0.39; 95% CI, 0.2-0.76), per clinician assessment. Patients in the IVIG plus corticosteroids group had a longer median inpatient stay (6 vs 5 days; P = .001) and longer median corticosteroid course duration (10 vs 5 days; P = .04) compared with the corticosteroids group. Forty-nine patients (71% of 69 in the corticosteroids group) recovered after receiving corticosteroid monotherapy for 10 days or less.

Conclusions And Relevance: Corticosteroid monotherapy is a reasonable management option for a subset of patients with MIS-C, particularly those with mild disease.