High eosinophil counts aid in diagnosing Kawasaki disease in febrile children

Abstract Background Several recent studies have validated the newfound significance of elevated eosinophils in Kawasaki disease (KD). However, this finding was not incorporated into the suggested laboratory criteria outlined by the Kawasaki Disease Committee of the American Heart Association for assessing children with incomplete KD. Purpose We aimed to determine the potential benefits of including eosinophil levels in the laboratory evaluation of KD. Methods A retrospective cohort study involved 77,934 febrile children (FC, not KD) and 1,970 subjects diagnosed with KD. Participants were recruited from four hospitals, comprising two medical centers and two regional hospitals. The AHA recommends specific laboratory tests—white blood cell count, hemoglobin, platelet count, ALT levels, albumin, and urinalysis—for evaluating incomplete KD in children with a higher CRP than 30mg/dL. The first four items are standard blood assays. Additionally, we introduced high eosinophil counts as a new diagnostic criterion for identifying children with KD. Results All these five laboratory findings (anemia for age defined as below the 5th percentile), platelet count >450,000/mm3, white blood cell>15,000/mm3, ALT>40 U/L, and eosinophil count >190/mm3) are significantly different between KD children and FC. The proportion of having these features is higher in KD children than in FC (19.3% vs. 8.0% in anemia for age, 20.5% vs. 10.3% in thrombocytosis, 37.0% vs. 18.1% in leukocytosis, 45.7% vs. 5.8% in elevated ALT, and 62.6% vs. 29.3% in high eosinophils). Elevated eosinophil counts are most commonly associated with KD among these five parameters. Furthermore, when incorporating the parameter of elevated eosinophil counts, the proportion of KD children with at least two abnormalities rose from 35.4% to 60.7%. In a subgroup analysis of children with KD presenting at least two abnormalities, the proportion rose from 38.7% to 63.5% in the high CRP group (≧ 3.0 mg/L) and 21.6% to 49.0% in the low CRP group (< 3.0 mg/L), respectively. Conclusions Higher eosinophil counts are vital markers in KD children. This aids in the identification of additional potential KD cases, especially in those exhibiting low CRP levels.