Role of individual and contextual effects in injury mortality: new evidence from small area analysis

Abstract

Objective: To analyse the role of individual and contextual variables in injury mortality inequalities from a small area analysis perspective, looking at the data for the city of Barcelona (Spain) for 1992-98. Setting: Barcelona (Spain). Methods: All injury deaths in residents older than 19, which occurred in the period 1992-98 were included (n=4393). Age and sex specific mortality rates were calculated for each educational level and each cause of death (traffic injuries, falls, drug overdose, suicide, other injuries). The contextual variables included were the proportion of men unemployed, and the proportion of men in jail, in each neighbourhood. Multilevel Poisson regression models were fitted using data grouped by age, educational level, and neighbourhood for each sex. Results: Death rates were higher in males, at the extremes of the age distribution (under 44 and over 74 years), and for lower educational levels. The results of the Poisson multilevel models indicate that inequalities by educational level follow a gradient, with higher risks for the population with no schooling, after having adjusted for the contextual variables of the neighbourhood. Such inequalities were more important in the youngest age group (20-34 years), as relative risk of 5.41 (95% confidence interval (CI) 3.9 to 7.4) for all injury causes in males and 4.38 (95% CI 2.3 to 8.4) in females. The highest relative risks were found for drug overdose. There was a contextual neighbourhood effect (the higher the deprivation, the higher the mortality) after having taken into account individual variables. Conclusion: The findings underscore the need to implement injury prevention strategies not only at the individual level taking into account socioeconomic position, but also at the neighbourhood level.A lthough the study of social inequalities in health has been broadened since the 1980s, inequalities in injuries have been studied somewhat less, 1 and most studies focus on children and the young. These show the existence of socioeconomic inequalities in injury mortality and morbidity, with the less privileged classes consistently showing higher injury rates. 2-11

Socio-economic inequalities in mortality due to injuries in small areas of ten cities in Spain (MEDEA Project)

“…Studies on suicides have reported a positive relationship between deprivation and mortality (Burrows et al, 2010;Chang et al, 2011;Esnaola et al, 2006;Middleton et al, 2006;Miller et al, 2005), however one systematic review found that the existence of this relationship depends on the size of geographical area analysed and on the variables used to measure deprivation (Rehkopf and Buka, 2006). In the case of falls, associations have also been reported between areas of greater deprivation and mortality due to this cause (Borrell et al, 2002;Esnaola et al, 2006). Finally, studies on traffic injuries are inconclusive in this regard.…”

The Effects of Area and Individual Social Characteristics on Suicide Risk: A Multilevel Study of Relative Contribution and Effect Modification

“…However, the relationships between these variables and suicide risk were not fully consistent: for residential mobility, family income, poverty rate, black racial concentration and poor female headed households, the significantly increased suicide risks are only observed at the intermediate levels. Borrell et al (2002) used multilevel Poisson regression models to study injury mortality including 804 suicides. After controlling for individual variables no relationship between the percentage of neighbourhood unemployment or the proportion of men in jail and suicide was observed.…”

Road crash involvement and professional status: A prospective study using the French Gazel cohort

“…Social inequalities exist with regard to the health burden of road safety: underprivileged subjects have the highest morbidity and mortality as a consequence of crash involvement (Borrell et al 2002;Cubbin et al 2000a). …”