Nationwide surveys show that the incidence of recurrent Kawasaki disease in Japan has hardly changed over the last 30 years.

AIM: Since Kawasaki disease (KD) was first reported in 1967, its aetiology has been intensively investigated, but remains unclear. We investigated the incidence of recurrent KD in Japan in 2003-2012, compared with previous data from our team, and assessed the potential risk factors for disease recurrence.
METHODS: Data from nationwide KD surveys were retrospectively analysed and 81 310 patients were observed. Incidence rates were compared between different years.
RESULTS: The incidence rates for recurrent KD were 3.89 per 1000 person-years (January 2003 to December 2012), 4.95 (July 2003 to December 2010), 6.48 (January 2003 to December 2006) and 6.51 (January 2007 to December 2010). These rates were almost consistent with our previous data, which started in the 1980s. The incidence rate for recurrence was statistically higher among males, patients under the age of three years and those who received intravenous immunoglobulin or steroid therapy at the initial episode. The presence of cardiac sequelae during the initial episode did not affect the recurrence incidence.
CONCLUSION: Although the incidence of KD has increased, the incidence of recurrent KD has remained largely unchanged over the past 30 years. Risk factors for recurrence included male sex, young age and initial resistance to immunoglobulin therapy. ©2017 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.