Background: The Japan Environment and Children’s Study (JECS) is a nation-wide birth cohort study involving 100,000 parent-child pairs that was conducted by the Japanese Ministry of the Environment. This study was started in 2011 to evaluate the effect of various environmental factors on children’s health and development. Health outcomes and exposure measurements will continue until the participating children become 13 years old.
Method: Exposure to environmental factors was assessed by chemical analyses of bio-specimens (blood, cord blood, urine, breast milk, and hair), household environmental measurements, and computational simulations using monitoring data, as well as questionnaires. The JECS’s priority outcomes include reproduction/pregnancy complications, congenital anomalies, neuropsychiatric disorders, immune system disorders, including Kawasaki disease (KD), and metabolic/endocrine system disorders. Genetic factors, socioeconomic status, history of infection, and lifestyle factors were also examined as covariates and potential confounders.
Results: Some of the questionnaires for children under 2 years old have already been collected. The numbers of patients with KD according to age were as follows: 14/71,133 (0.02%) between 0-6 months old, 102/51,351 (0.2%) between 6-12 months old, 71/34,595 (0.21%) between 12-18 months old, and 20/20,995 (0.1%) between 18-24 months old. According to these results, the estimated incidence of KD in children younger than 2 years old could reach more than 0.5%, but this number may increase after further collection of questionnaires. We also conducted a secondary survey regarding KD patients, including family history, clinical symptoms, laboratory data, treatment, and outcome.
Conclusion: Recently, similar birth cohorts to JECS were already initiated in many countries, but this is the first large-scale birth cohort focusing KD. The results of this cohort may shed new light on the environmental pathogenesis of KD.