Breastfeeding and Risk of Kawasaki Disease: A Nationwide Longitudinal Survey in Japan

BACKGROUND AND OBJECTIVES: Kawasaki disease (KD) is the most common cause of childhood-acquired heart disease in developed countries. However, the etiology of KD is not known. Aberrant immune responses are considered to play key roles in disease initiation and breastfeeding can mature immune system in infants. We thus examined the association between breastfeeding and the development of KD. METHODS: We used a nationwide population-based longitudinal survey ongoing since 2010 and restricted participants to a total of 37630 children who had data on their feeding during infancy. Infant feeding practice was queried at 6 to 7 months of age, and responses to questions about hospital admission for KD during the period from 6 to 30 months of age were used as outcome. We conducted logistic regression analyses controlling for child and maternal factors with formula feeding without colostrum as our reference group. RESULTS: A total of 232 hospital admissions were observed. Children who were breastfed exclusively or partially were less likely to be hospitalized for KD compared with those who were formula fed without colostrum; odds ratios for hospitalization were 0.26 (95% confidence interval: 0.12-0.55) for exclusive breastfeeding and 0.27 (95% confidence interval: 0.13-0.55) for partial breastfeeding. Although the risk reduction was not statistically significant, feeding colostrum only also provided a protective effect. CONCLUSIONS: We observed protective effects of breastfeeding on the development of KD during the period from 6 to 30 months of age in a nationwide, population-based, longitudinal survey in Japan, the country in which KD is most common.