Kawasaki disease, an acute febrile illness of childhood, was described in Japan in 1967 by Dr. Tomasaku Kawasaki as the mucocutaneous lymph node syndrome. A vasculitis of medium-sized vessels, Kawasaki disease has a predilection for the coronary arteries, and 20% to 25% of untreated children develop coronary artery aneurysms. Fortunately, a regimen of intravenous immunoglobulin and aspirin reduces the incidence of coronary artery abnormalities to less than 5%. Nonetheless, Kawasaki disease is the leading cause of acquired heart disease in children in North America and Japan. Furthermore, the etiology of Kawasaki disease remains elusive, impeding the development of targeted therapy and diagnostic testing.
EPIDEMIOLOGY AND SPECIFIC POPULATIONS AT RISK
The Japanese Ministry of Health collects epidemiologic data on Kawasaki disease every 2 years with nationwide surveys and has done so since 1970. In total, approximately 300,000 cases of Kawasaki disease were reported in Japan between 1970 and 2012. In addition to endemic disease, 3 epidemics of Kawasaki disease occurred in Japan in 1979, 1982, and 1986, with an incidence of 196.1 cases per 100,000 children less than 5 years of age in 1982, the most severe of the epidemics. Interestingly, there have been no recent epidemics, but surveys reveal a steady increase in the incidence of Kawasaki disease. The incidence of Kawasaki disease in Japan in 2012 was 264.8 per 100,000 in children younger than 5 years of age, the highest reported incidence to date.
In contrast to Japan, rates of Kawasaki disease in the United States have been stable for approximately the past 2 decades. The hospitalization rates for Kawasaki disease in the United States were 19 per 100,000 children less than 5 years of age in 2009, 19.6 per 100,000 children in 2003, and 17.5 per 100,000 children in 1997. Children of Asian and Pacific Islander heritage have consistently higher hospitalization rates in the United States, a finding consistent with the hypothesis that Kawasaki disease results from unidentified environmental triggers in genetically susceptible hosts. Furthermore, siblings of patients with Kawasaki disease may be at higher risk for developing the disease, and parents of affected children in Japan are twice as likely to have a history of Kawasaki disease themselves.
RISK FACTORS FOR POOR OUTCOMES
Risk factors for poor coronary artery outcomes have been identified in a number of studies. A study using the Centers for Disease Control and Prevention (CDC) passive surveillance system for Kawasaki disease found that coronary artery aneurysms were significantly associated with age less than 1 year or greater than 9 years, male sex, Asian and Pacific Islander race, and Hispanic ethnicity. A number of investigators have created predictive models to identify risk factors for poor clinical outcome. Young age, male sex, and a number of laboratory parameters, including neutrophilia, thrombocytopenia, hyponatremia, elevated C-reactive protein, and transaminitis, have been associated with poor response to intravenous immunoglobulin or ...