Social differences in injury risk in childhood and youth : exploring the roles of structural and triggering factors

Sammanfattning: Injuries are a leading cause of mortality and morbidity among children and adolescents. Injury risks are not randomly distributed across social groups. The primary aim of this thesis is to increase knowledge about the determinants of the social distribution of injuries among children and adolescents. Family-related social characteristics and peer victimisation in the school environment are studied separately and in combination. The first three studies, based on Swedish national registers, investigate the importance of socioeconomic status and various other family-related social factors (e.g. receipt of welfare benefit, family constellation, parental country of birth, and population density of living area) for the risk of injury at different ages. Four types of injuries are considered: fall-, traffic-, and two types of violence-related injuries - those caused by self-harm and those due to interpersonal violence. Two other studies, regional and interview based, investigate the triggering effect of peer victimisation in school on the risk of injuries among 10-15 year-olds, and also the effect modification of familyrelated socioeconomic characteristics. Socioeconomic differences in injury risks among Swedish children and adolescents are considerable, and appear to be age- and diagnosis-specific. Among the youngest children, both absolute and relative differences are small for fall and traffic injuries. Whereas the greatest absolute differences are found among 15-19 year-olds - in traffic injuries for boys and in self- inflicted injuries for girls - the greatest relative ones are found among 10-14 year-olds, for injuries caused by interpersonal violence. Processes of equalisation with age, measured as a reduction in relative differences in injury risks, occur solely in the case of traffic and self-inflicted injuries in girls. When various social characteristics of the family are considered, one by one and adjusted for each other, and focus is placed on intentional injuries in adolescents, living in a family having received welfare benefit is the characteristic with the strongest association with injury risk. To some extent, receipt of welfare benefit is likely to be a mediator of the effect of other factors, such as socioeconomic status of the household and parental country of birth. Peer victimisation increases the risk of unintentional injury for a short period after an episode has occurred (1-15 minutes), but not thereafter. The effect is higher for children who are seldom or never victimised than for those who are often victimised. Socioeconomic status and level of education of the household do not significantly modify the effect of peer victimisation on injury risk. The age- and diagnosis-specificity of social differences in injury risks can be important for the setting of priorities regarding preventive strategies, and also for understanding of the social aetiology of childhood and adolescent injuries. Whereas the observed association between household socioeconomic status and the risk of unintentional injuries is not affected by other household attributes, association with the risk of intentional injuries is. The extent to and manner in which household socioeconomic status affect the relationship between peer victimisation and the risk of unintentional injury deserve further investigation.