Rising Kawasaki disease incidence in New Zealand: analysis of national population incidence and outcomes 2000-2017.

OBJECTIVE: The recent epidemiology of Kawasaki disease (KD) in New Zealand (NZ) is unknown. Our aim was to describe the incidence, seasonal variation, long-term outcomes and mortality for KD in NZ.

DESIGN: Retrospective national database analysis.

SETTING: New Zealand.

PATIENTS: First hospitalisation and deaths diagnosed with KD.

MAIN OUTCOME MEASURES: Data were extracted for all hospital admissions in NZ coded as KD (International Classification of Diseases (ICD)-9 and ICD-10) from the National Minimum Dataset 1 January 2000 to 31 December 2017. Age, sex, ethnicity and associated diagnoses were available to review. Intervention rates for immunoglobulin administration were also analysed.

RESULTS: Over the study period, there were 1008 children with initial hospitalisation for KD. The mean age was 39.8 months (SD 37) and 592 (59%) were boys. The annual incidence rate of KD has increased from 12.2 to 19.5 per 100 000 children <5 years old (0.46 case increase per year; 95% CI 0.09 to 0.83). Children of Asian and Pacific Island ethnicities had the highest incidence (51.2 and 26.1/100 000, respectively). The highest growth in incidence was among East Asian children. The case mortality rate was low (12 of 1008, 1.2%); however, Māori were over-represented (6 of 12 deaths).

CONCLUSIONS: There is evidence of increasing KD hospitalisation in NZ, similar to recent studies from Northeast Asia and Australia. KD incidence data were available for retrospective review from a national database, but data on complications and outcomes were incomplete. Notification for KD and an active national surveillance system are recommended to improve care. Future work should focus on factors contributing to poorer outcomes in Māori.