Seasonality of child and adolescent injury mortality in Japan, 2000-2010

Injury is the leading cause of death among children and adolescents in Japan. Despite this, until now there has been comparatively little research on this phenomenon. The purpose of this study was to examine if there was seasonal variation in child and adolescent injury mortality in Japan in 2000-2010. Vital statistics injury mortality data were obtained from the Ministry of Health, Labour and Welfare of Japan. The seasonality of the major causes of unintentional injury (transport accidents, drowning and suffocation) and intentional injury (suicide and homicide) mortality was examined for children and adolescents aged 0-19. Incidence ratios (IR) with 95 % confidence intervals (CI) were calculated to determine the difference between the numbers of observed and expected seasonal deaths. The annual average injury mortality rate among children and adolescents was 9.0 per 100,000. Deaths from transport accidents, drowning, suffocation and suicide had a significant seasonality. There was a summer peak for transport accidents (IR 1.15, 95 % CI 1.10-1.19) and drowning (IR 2.00, 95 % CI 1.88-2.11), a spring peak for suicide (IR 1.09, 95 % CI 1.04-1.14), while the incidence of suffocation was higher in winter (IR 1.12, 95 % CI 1.03-1.21). Child and adolescent injury mortality from transport accidents, drowning, suffocation and suicide has a pronounced seasonality in Japan. More research is now needed to find the circumstances underpinning different forms of injury mortality in different periods of the year so that effective interventions can be designed and implemented to reduce the burden of injury mortality among Japanese children.