Diagnosis of Systemic-Onset Juvenile Idiopathic Arthritis after Treatment for Presumed Kawasaki Disease

Objectives To estimate the incidence of systemic-onset juvenile idiopathic arthritis (SoJIA) within 6 months after treatment for presumed Kawasaki disease (KD) (presumed patients with KD with subsequent diagnosis of SoJIA [pKD/SoJIA]) and describe presentation differences from sole KD. Study design We identified patients treated for KD at Nationwide Children's Hospital and from the Pediatric Health Information System from 2009-2013. We then identified the subset of children, pKD/SoJIA, who received an International Classification of Diseases, Ninth Revision code for SoJIA and had it listed at least once 3 months after and within 6 months after KD diagnosis. Demographic characteristics, readmission rates, treatments, and complications were noted. A literature review was also performed to identify clinical, laboratory, and echocardiographic data of previously documented patients with KD later diagnosed with SoJIA. Results There were 6745 total treated patients with KD in the Pediatric Health Information System database during the study period; 10 patients were identified to have pKD/SoJIA (0.2% of cohort). Those with pKD/SoJIA were predominantly Caucasian compared with patients with KD (90% and 46.8%, respectively; P = .003). Macrophage activation syndrome was more common in patients with pKD/SoJIA than in sole patients with KD (30% and 0.30%, respectively; P < .001). Fifteen cases of pKD/SoJIA were identified by literature and chart review, 12 of whom were initially diagnosed with incomplete KD. Conclusions We reported a 0.2% incidence of pKD/SoJIA, which was associated with Caucasian race, macrophage activation syndrome, and an incomplete KD phenotype.