Kawasaki disease, autoimmune disorders, and cancer: a register-based study.

Kawasaki disease has well-described cardiovascular complications. However, the association to autoimmunity and cancer in the long term is not well described. We investigated theses associations using a registry-based matched cohort follow-up study of patients diagnosed with Kawasaki disease. Patients with Kawasaki disease were included and matched 1:5 to a population control group, matched by birth year, sex and incident month of the Kawasaki disease diagnosis. A total of 820 cases < 21 years of age were identified. Median age at diagnosis was 3 years. Median follow-up time was 12 years. Patients with KD were at higher risk of being diagnosed with ischaemic heart disease at 10 years (HR 39.94 (95% CI 5.00-319.28)) and 30 years (HR 8.33 (95% CI 3.03-22.91)). The 10-, 20- and 30-year risks of developing autoimmune disorders were HR 4.23 (95% CI 3.01-5.94), HR 3.23 (95% CI 2.44-4.29) and 2.83 (95% CI, 2.17-3.68), all p < 0.001. Cancer risk was increased after 30 years (HR 2.42 (95% CI, 1.09-5.34)). All-cause mortality after 35 years was also significantly increased (HR 3.14 (95% CI, 1.03-9.60)). Children with KD have increased long-term risks of ischaemic heart disease also of autoimmune disease and cancer, as well as an increased all-cause mortality. The surprisingly increased risk of autoimmunity must be investigated further. What is known: • Kawasaki disease is characterized by acute vasculitis and inflammation that can affect the coronary arteries. • Anti-inflammatory medicine is effective in the acute stages of the disease. What is new: • Children with Kawasaki disease have an increased risk of developing autoimmune disease in the long term. • Kawasaki disease is associated with a slightly increased mortality rate driven by non-cardiovascular causes.