Kawasaki disease incidence in children and adolescents: an observational study in primary care.

BACKGROUND Kawasaki disease is reported to be increasing in incidence and is the commonest childhood cause of acquired heart disease in the Western world. AIM To determine the current UK incidence of Kawasaki disease across childhood and adolescence; and investigate trends over time and season. DESIGN AND SETTING An observational, descriptive study in the UK. METHOD The Health Improvement Network (THIN) database of primary healthcare records was searched for codes or text indicating Kawasaki disease. Identified records were compared with a study case definition and a date of onset was assigned to cases. The incidence, age/sex distribution, and trend in seasonal and temporal distribution were estimated (2008-2012). RESULTS A total of 110 episodes of Kawasaki disease in 109 children were identified from 3.9 million person-years observation. The incidence of Kawasaki disease was 2.8 per 100 000 person-years (95% confidence interval [CI] = 2.3 to 3.4) when aged <20 years; 9.1 (95% CI = 7.3 to 11.2) aged <5 years, and 3.0 per 100 000 (95% CI = 2.0 to 4.3) across the age groups when possible cases were included. More cases were identified in males (55%) with one-fifth of cases diagnosed after 5 years of age. There was no statistically significant trend in incidence over the study years (P = 0.10 adjusted for sex and month), or between seasons (P = 0.65 adjusted for year and sex). CONCLUSION Although the incidence of Kawasaki disease remains low and has stabilised in the UK, GPs should recognise that the condition occurs throughout childhood and across the seasons.