Association of early social environment with the onset of pediatric Kawasaki disease

Abstract Purpose The purpose of this study was to investigate the association of early social environment with Kawasaki disease (KD). Methods We analyzed the data of children aged up to 10 years derived from the 21st Century Longitudinal Survey in Newborns ( n  = 41,872) in Japan. Parental education, total household income, and family size were obtained via a questionnaire at 0.5 years after birth. Physician's diagnosis of KD during the past year was surveyed via a questionnaire for caregiver with children aged up to 10 years. We used Cox proportional hazards modeling to examine the risk factors for KD onset. Results Children born in households with an annual income of JPY 10 million or more were 1.76 times more likely to have KD onset compared with children born in households with an income of less than JPY 4 million (hazard ratio: 1.76, 95% confidence interval [CI]: 1.15–2.69). Children born in households with three or less persons were 1.62 times more likely to have KD onset compared with those born in households with six or more persons (95% CI: 1.10–2.40). The children who were born in urban municipalities also showed higher risk of KD onset compared with those born in rural municipalities (hazard ratio: 1.55, 95% CI: 1.06–2.26). Conclusions Higher household income, smaller family size, and urbanization at birth were associated with increased KD incidence. This study, however, did not find a significant association between lack of exposure to infection in early life and onset of KD.