Association of Kawasaki disease with urbanization level and family characteristics in Taiwan: A nested case-control study using national-level data.

Kawasaki disease (KD) is an inflammatory vasculitis disorder of unknown etiology. It is a rare but fatal disease and the leading cause of acquired coronary heart disease in children under the age of 5 years. We examined the association of KD with the demographics of family members, parents' characteristics, and perinatal factors in Taiwanese children. This nested case-control study used data from Taiwan's Health and Welfare Data Science Center and initially included children born in Taiwan between January 1, 2006, and December 31, 2015 (n = 1,939,449); the children were observed for KD development before the age of 5 years (n = 7870). The control group consisted of children without KD who were matched with each KD case by sex and birth date at a ratio of 8:1. The odds ratio (ORs) of the aforementioned associations were estimated using conditional logistic regression. The risk of KD decreased in children with younger parents [<25 years; younger maternal age, OR = 0.72, 95% confidence interval (CI), 0.66-0.79; younger paternal age, OR = 0.68, 95% CI, 0.59-0.78], lower socioeconomic status, more than 2 siblings (OR = 0.80, 95% CI, 0.73-0.89), and siblings with a history of KD (OR = 4.39, 95% CI, 3.29-5.86). Children living in suburban (OR = 0.95, 95% CI, 0.90-1.00) and rural (OR = 0.81, 95%CI, 0.74-0.90) areas exhibited a lower risk of KD than children living in urban areas. In conclusion, a higher incidence rate of KD was observed in children aged <5 years who had an urban lifestyle, had siblings with KD, were born to older mothers, and belonged to high-income and smaller families. Parental allergic or autoimmune diseases were not associated with the risk of KD.