Serum biomarkers differentiating Kawasaki disease from febrile infections: A pilot case-control study.

Although some serum biomarkers are elevated in both Kawasaki disease (KD) and infections, these conditions have not been compared by individual or combined biomarkers. The aim of this study, undertaken between January 2016 and May 2018 in a large teaching hospital, was to compare the serum concentration of cytokines, metalloproteinases (MMP) and heat shock protein (HSP) between cases defined as children with Kawasaki disease (KD) and those with febrile infections (controls). Serum concentrations of tumour necrosis factor-alpha (TNF-alpha), interleukins (IL 1beta, 6, and 8), heat shock proteins (HSP 60 and 70) and matrix metalloproteinase (MMP 9) were measured on admission in 17 children under six years of age with a temperature >38.5 °C for ≥five days, and compared between the two groups. The median age was 25 months and the median duration of fever eight days. Seven children were diagnosed with KD and ten had a febrile infection. Only the serum concentrations of IL-6 and TNF-alpha were significantly higher in the former than in the latter group (P = 0.01 and 0.04 respectively). To differentiate between the two groups with the best sensitivity and specificity, the optimal cut-off value for IL-6 was 12.6 pg/mL, and for TNF-alpha 47.9 pg/mL. Their combined increase, however, outperformed their individual concentrations. The characteristic diagnostic "signature" of the combined elevation of IL-6 and TNF-alpha serum levels has the potential, in febrile children, to differentiate early KD from febrile infections, allowing the institution of appropriate therapy.