Assessing the Response of Biomarkers to Anti-Inflammatory Medications in PIMS-TS by Longitudinal Multilevel Modeling: Real-World Data from a UK Tertiary Center.

Pediatric inflammatory multisystem syndrome temporarily associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (PIMS-TS) is an acute complication of previous SARS-CoV-2 exposure. The relationship between inflammatory markers and anti-inflammatory medication in PIMS-TS is unknown. We retrospectively investigated the relationship between demographics, biomarkers, treatment, and length of stay (LOS) in this novel disease. We reviewed the case notes and blood tests of all patients who met the Royal College of Paediatrics and Child Health diagnostic criteria for PIMS-TS at a large tertiary center in the United Kingdom. Biomarker trajectories were modeled using log linear mixed effects, and factors affecting LOS in hospital were evaluated using multiple regression. Between March 2020 and May 2022, a total of 56 patients attended Sheffield Children's Hospital with PIMS-TS, 70% male. Mean age was 7.4 ± 3.7 years and mean LOS 8.7 ± 4.5 days with 50% requiring intensive care and 20% requiring inotropes. Older males had shorter LOS than younger males ( = 0.04), not seen in females. Treatment included intravenous glucocorticoids in 93%, intravenous immunoglobulins (IVIG) in 77%, Anakinra in 11%, and infliximab in 1.8%. Biomarkers correlated poorly with trajectories that peaked at different times. C-reactive protein peaked first after median 1.3 days postadmission; while LFT's and neutrophils peaked after 3 days. Age had a large effect on some biomarkers, with older children having larger troponin and ferritin, and lower lymphocytes and platelets. Cumulative dose of glucocorticoids and IVIG had a statistically significant effect on some biomarkers, but effect size was small. The heterogenous nature of PIMS-TS highlights the importance of a multidisciplinary approach. Worse inflammatory markers in older children within our cohort may be an indication of a different disease process occurring at different ages. Future work to investigate the association between age and troponin and ferritin in hyperinflammatory states is warranted.