Socioeconomic status and injury mortality: individual and neighbourhood determinants

STUDY OBJECTIVE This study examined both individual and neighbourhood correlates of injury mortality to better understand the contribution of socioeconomic status to cause specific injury mortality. Of particular interest was whether neighbourhood effects remained after adjusting for individual demographic characteristics and socioeconomic status. DESIGN Census tract data (measuring small area socioeconomic status, racial concentration, residential stability, urbanisation, and family structure) was merged with the National Health Interview Survey (NHIS) and a file that links the respondents to subsequent follow up of vital status and cause of death data. Cox proportional hazards models were specified to determine individual and neighbourhood effects on homicide, suicide, motor vehicle deaths, and other external causes. Variances are adjusted for the clustered sample design of the NHIS. SETTING United States, 1987–1994, with follow up to the end of 1995. PARTICIPANTS From a sample of 472 364 persons ages 18–64, there were 1195 injury related deaths over the follow up period. MAIN RESULTS Individual level effects were generally robust to the inclusion of neighbourhood level variables in the models. Neighbourhood characteristics had independent effects on the outcome even after adjustment for individual variability. For example, there was approximately a twofold increased risk of homicide associated with living in a neighborhood characterised by low socioeconomic status, after adjusting for individual demographic and socioeconomic characteristics. CONCLUSIONS Social inequalities in injury mortality exist for both persons and places. Policies or interventions aimed at preventing or controlling injuries should take into account not only the socioeconomic characteristics of people but also of the places in which they live.