Variability in Diagnosis and Treatment of Kawasaki Disease across the United States.

Objective: To analyze demographic characteristics, treatment, and outcome of patients with Kawasaki disease (KD), an acute vasculitis of children with unknown etiology, to gain insight into variation in care and epidemiologic clues regarding the etiology of KD. Study design: We analyzed the first admission of children diagnosed with KD and treated with intravenous immunoglobulin (IVIG) between 2015 and 2019 across the US and studied the monthly diagnosis of KD by age group and geographic location. We evaluated the use of adjunctive therapies, including patients with giant coronary artery aneurysms (gCAAs) who were treated with systemic anticoagulation after IVIG treatment. Results: We identified 8037 patients with acute KD in 45 hospitals. The seasonal cycle of patients ≤6 months old differed from that of other age groups, with regional variability noted between the Western and Southern US. The rate of adjunctive therapy use ranged from 14.8% to 85.6% at individual hospitals. There was significant variability in the choice of adjunctive agents, with regional differences in the use of corticosteroids and infliximab. There were 138 patients with gCAAs (1.7%), of whom 42 (30.4%) received no additional anti-inflammatory therapies beyond IVIG, despite 26.8% of these aneurysms being present at the time of diagnosis. Conclusions: Distinct temporal signatures of KD diagnosis across age groups suggest different age-related mechanisms of exposure. Significant practice variation exists in the use of adjunctive therapy in patients with KD with and without gCAAs. Future head-to-head comparisons of adjunctive agents in high-risk patients will be necessary to guide best practice.