Twelve Years of Kawasaki Disease in Portugal: Epidemiology in Hospitalized Children.

Background: Kawasaki disease (KD) is the leading cause of acquired heart disease in developed countries. Reported incidences vary worldwide but incidence of KD has not been established in Portugal.

Aim: The aims of the study were to describe the epidemiologic characteristics and estimate incidence rates of KD among hospitalized children in Portugal.

Methods: This study was a descriptive, population-based study, which used hospital discharge records of patients <20 years of age diagnosed with KD from the Hospital Register database for 2000-2011. Incidence rates were calculated using the number of KD patients and corresponding National census data.

Results: There were 533 hospitalizations of 470 patients with KD as the primary diagnosis in Portugal, 63 hospitalizations were transfers of patients between hospitals and there were no relapses. The mean age at admission was 2.8 years, with male predominance (male-to-female ratio: 1.6:1). Children <5 years and infants <1 year represented 83% and 23% of all the patients admitted, respectively. Mean annual incidence was 6.5 per 100,000 children <5 years, 4.5 per 100,000 infants <1 year and 7.8 per 100,000 infants 1-4 years. We found considerable differences between national territorial regions, with majority of cases in most dense regions. The mean length of hospital stay was 9 days, and the incidence peaked in spring (35%) and spring/winter (63%). Coronary aneurysms were reported in 8.5% of patients with a higher male-to-female ratio (3.4:1) and a lower mean age (1.93 years). Reported mortality was 0.4%.

Conclusions: This is the first large-scale epidemiologic study of KD in Portugal. The highest incidences occurred among male children 1-4 years of age and in spring/winter.