Comparison of methylprednisolone alone versus intravenous immunoglobulin plus methylprednisolone for multisystem inflammatory syndrome in children (MIS-C).

Background: As a first-line therapeutic option for multisystem inflammatory syndrome in children (MIS-C) with surging demand, intravenous immunoglobulin (IVIG) is associated with escalating costs and supply shortages, particularly in low-income and middle-income countries. This study compares the effectiveness of methylprednisolone alone versus IVIG combined with methylprednisolone for managing MIS-C.

Methods: We conducted a retrospective cohort study from January 2022 to June 2023 at Vietnam National Children's Hospital. We used propensity score matching to compare the short-term outcomes based on immunomodulatory therapy with methylprednisolone alone or IVIG plus methylprednisolone.

Results: We included 391 patients, comprising 255 boys and 136 girls, who fulfilled the MIS-C case definition of the US Centers for Disease Control and Prevention. Most patients (80.8%) received intravenous methylprednisolone monotherapy, and 19.2% were administered IVIG in addition to methylprednisolone. In general, the laboratory values indicative of hyperinflammatory and hyperthrombotic states displayed significant early response within 2-3 days after initial treatment, including white cell count (SE=1.77, p<0.001), NEU (SE=0.76, p=0.03), C reactive protein (SE=-46.51, p<0.001), PLT (SE=38.05, p=0.002), fibrinogen (SE=-0.37, p=0.002), d-dimer (SE=-849.8, p=0.02)); while subsequent improvement in cardiac markers was also observed, with pro-B-type natriuretic peptide (SE=-165.2, p<0.001) on day 5 and troponin I (SE=-0.05, p=0.004) on day 7. After propensity score weighting, there were 41 patients in each treatment group. Notably, there were no significant differences in the incidence of cardiac events between treatment groups regarding left ventricular dysfunction and coronary artery dilation or aneurysms (10.3% vs 20.7%, p=0.074 and 63.4% vs 56.1%, p=0.653, respectively). While the median paediatric intensive care unit length of stay (LOS) and hospital LOS were slightly lengthier in the IVIG and methylprednisolone group compared with those of the methylprednisolone group, these differences were not statistically significant ((5 vs 4, p=0.782) and (9 vs 7, p=0.725), respectively).

Conclusions: Initial treatment with methylprednisolone monotherapy appears not inferior in effectiveness to adjunctive IVIG plus methylprednisolone in MIS-C. Further investigations in randomised controlled trials deserve to be undergone to clarify if IVIG-sparing glucocorticoids are a viable option for achieving favourable outcomes in MIS-C, particularly in resource-limited settings with barriers approaching IVIG therapy.