63 - NT-PROBNP VARIATION ACCORDING TO THE TIME TO DIAGNOSIS IN MULTISYSTEM INFLAMMATORY SYNDROME IN CHILDREN

BACKGROUND/

Aim: In multisystem inflammatory syndrome in children (MIS-C or PIMS temporally associated with SARS-CoV-2), N-terminal pro-B-type natriuretic peptide (NT-proBNP) is used for differential diagnosis with Kawasaki disease but contrasting cut-offs have been suggested. The association between NT-proBNP and time from first symptoms to diagnosis, called time to diagnosis, has been poorly described. The aim of the present study was to assess the variation of NT-proBNP values at diagnosis depending on the time to diagnosis.

Methods: A single-centre cohort observational study included patients with MIS-C, according to the World Health Organization definition, from May 2020 to April 2023. The NT-proBNP values until diagnosis were collected retrospectively and correlated to the time to diagnosis.

Results: Thirty-seven children (19 (51%) males, median age (interquartile range) 8.8 (5.6 - 10.8) years, 18 (49%) with clinical signs of shock, and 12 (32%) with complete clinical Kawasaki criteria) were included. Median NT-proBNP at diagnosis was 8,558 (1,920 - 16,836) pg/mL and median time to diagnosis was 5.3 (4.1 - 6.2) days. NT-proBNP at diagnosis was positively correlated with time to diagnosis up to 6 days (ρ = 0.76, 95% confidence interval 0.54 to 0.88, p < 0.0001) but not when time to diagnosis was longer than 6 days (ρ = − 0.25, 95% confidence interval − 0.67 to 0.30, p = 0.332). NT-proBNP until diagnosis was significantly higher at 6 days (32,933 (7,773–61,592) pg/mL) than at 3 days (1,994 (1,291–4,190) pg/mL) from the first symptoms (p = 0.031).

Conclusion: NT-proBNP at diagnosis increased up to a time to diagnosis of 6 days, suggesting different thresholds for positive and differential diagnosis in early versus delayed diagnosis.