(171) Shock Index as a Predictor of Adverse Outcomes in MIS-C

Introduction: Multisystem Inflammatory Syndrome in Children (MIS-C) is a significant source of morbidity and mortality in children infected with COVID-19. Most patients present with mild symptoms, and early identification of those at risk for severe disease ensures prompt escalation of care and appropriate allocation of limited resources. The shock index (SI), calculated as HR/SBP, has the advantage of broad applicability across a wide age range, which may simplify severity stratification in shock states. It has shown potential utility for this purpose in blunt trauma, congenital cardiac surgery, and sepsis. However, there are no published data regarding the utility of SI in MIS-C. We hypothesized that the maximum SI in the first 24 hours of PICU admission (SI24) could predict adverse outcomes.

Methods: We identified 96 patients aged 1mos-18yrs admitted to a tertiary PICU with a primary diagnosis of MIS-C and collected data retrospectively. The primary outcome was a composite of three major adverse events: CPR, ECMO cannulation, or mortality. Secondary outcomes included incidence of arrhythmia. Based on preliminary ROC curve analysis, the optimal cut-point for SI24 was identified as ≥1.6. Contingency tables for major adverse events and arrhythmia were constructed and analyzed using Fisher’s exact test. Data were considered significant when the two-tailed p value was >0.05.

Results: Our patient sample was skewed towards school-aged children, with 79 (80.6%) of patients aged 4-18 years. Of 96 patients, 9 (9.4%) experienced a major adverse event, and 15 (15.6%) had arrhythmia. Arrhythmias included accelerated junctional rhythm and ventricular arrhythmia. SI24 was ≥1.6 in 66% of patients with a major adverse event (LR 1.12, p=0.289) and 80% of patients with arrhythmia (LR 6.78, p=0.009).

Conclusions: Patients with MIS-C whose peak SI is ≥1.6 in the first 24 hours of PICU admission are more likely to experience arrhythmias, but the association of SI24 with other adverse outcomes is weak. SI may be a more useful tool than primary hemodynamic measurements for communicating and comparing the severity of shock in MIS-C. We propose that children with MIS-C who have a SI ≥1.6 should receive immediate escalation of care to an ICU setting for prompt initiation of anti-inflammatory therapies under close monitoring.