Mortality rates for patients with a history of Kawasaki disease in Japan

Objective: To determine whether the mortality rate of patients with a history of Kawasaki disease is higher than that of the general population. Design: In a cohort study, 6585 patients with Kawasaki disease were observed from the first medical encounter because of the disease through the end of 1992, or until death, Standardized mortality ratios (SMRs) with 95% confidence intervals (CI) were calculated with vital statistics data of Japan for the control. Results: Of 6585 patients who met the eligibility criteria, 6550 (99.5%) were followed through either the end of the study or the date of death. Nineteen patients (14 male subjects) died during the study period; an overall SMR of 1.56 (95% CI, 0.94 to 2.43) was calculated for the entire study period. The SMR was 1.78 (95% CI, 0.97 to 2.99) for male subjects and 1.16 (95% CI, 0.38 to 2.71) for female subjects. During the acute phase of the disease (the first 2 months after onset), the SMR was higher, particularly in male subjects (SMR, 10.12; 95% CI, 3.72 to 22.07). After the acute phase, however, both boys and girls had low SMRs. Nine of the 19 deaths were caused by Kawasaki disease; there were 2 deaths as a result of congenital anomalies of the circulatory system and 2 subjects died of malignant neoplasms of lymphatic or hematopoietic tissues. Conclusions: Although the mortality rate among those with a history of Kawasaki disease was elevated in Japan, many of the deaths that caused the elevation occurred during the acute phase of the disease. The mortality rate was not increased after the acute phase of the disease.