Decomposing the impact of deprivation on child pedestrian casualties in England

Abstract

The incidence of child injury due to road traffic accidents appears to be positively associated with socio-economic deprivation. However, the reasons behind this relationship have proven difficult to identify. In this paper, we present results from a cross-sectional analysis using generalized linear regression models of child pedestrian casualties for the wards of England. We find that there are distinct and substantial effects on casualty rates from characteristics associated with area deprivation across diverse environments. These associations exist over and above influences arising from local environmental characteristics. Distinct dimensions of deprivation appear to affect the incidence of pedestrian casualties to varying degrees and sometimes in different directions. The results identify a relationship between income deprivation and the incidence of child pedestrian casualties, but they also show that poverty is only one aspect of deprivation that matters. In particular, we find a consistent positive influence from crime related deprivation.

Introduction

The existence of a statistical relationship between socio-economic deprivation and health has frequently been proposed in the literature (e.g. Lancaster and Green, 2002, Cooper, 2002, Lorant et al., 2001, Gould and Duncan, 2000, Diamond et al., 1999, Carstairs and Morris, 1991, Townsend et al., 1988, Jarman, 1983). Specifically, higher levels of deprivation are found to be associated with poor health. Research has sought to test the presence and strength of such associations, but has also frequently addressed issues relating to how deprivation is actually measured and how deprivation indices are constructed.

Recent findings indicate that the incidence of injuries amongst children is particularly influenced by deprivation. Hippisley-Cox et al. (2002) find that children from the most deprived social classes have a mortality rate from injury five times that of children from the least deprived social class, while Roberts and Powers (1996) have shown that the social class gradient is prevalent over the most common mechanisms of injury.

Pedestrian road accidents are a major source of injuries to children. Research on the relationship between child pedestrian casualties and the socio-economic characteristics of victims supports the deprivation hypothesis: children of the lowest social class are approximately four times more likely to be killed on the road than those of the highest social class (see White et al., 2000, Christie, 1995 for reviews of this literature).

The factors that lie behind this observed relationship are multi-faceted and often highly inter-correlated. Although the existing literature does not provide us with an exact or comprehensive understanding, individual level studies of child pedestrian casualties do provide some indication of factors that may be of importance. These include poor housing accommodation and lack of open space for playing at home (Roberts and Pless, 1995), low levels of access to car passenger transport for children (Erskine, 1996), increased exposure to hazardous traffic environments and increased proximity to busy streets Bagley, 1992, Christie, 1995, Roberts et al., 1995, lower levels of child supervision within households (Christie, 1995), the scarcity of publicly available play spaces (Al-Balbissi et al., 1990), and the tendency of deprived children to play unsupervised close to home (Sharples et al., 1990).

Despite evidence such as this we still do not have a precise understanding of how socioeconomic status affects road accident rates. This is because many of the factors cited in the individual studies could be prevalent to equal degrees in both deprived and non-deprived locations. Indeed, for several of the factors cited above we could argue that variation is based at least as much on urban density as it is on deprivation. Thus, we need to be clear about what we are trying to capture when we measure deprivation, and we need to try to make deprivation measures distinct from other prominent influences on the incidence of child casualties.

In this paper we focus on the measurement of deprivation and the construction of the deprivation index in an attempt to shed light on relationships between area deprivation and the incidence of child pedestrian casualties. We decompose the deprivation effect by considering six separate dimensions related respectively to income, employment, health, education, housing and services, and crime. Our principal research question is whether the different dimensions of deprivation affect the incidence of child pedestrian casualties in different ways. If they do, we wish to obtain statistical quantification of the association between each distinct aspect of deprivation and the incidence of child pedestrian casualties in England.

We present results from models derived to explain variation in child pedestrian casualties (CPCs) according to a range of location-specific characteristics, a subset of which are the components of deprivation. It is important to emphasize that our analysis is area based. Unlike the individual studies quoted above, our observations are spatial units, not people or family groups. The deprivation scores characterize the socio-economic profile of 7925 small areas of England. As such we cannot directly determine an association between the incidence of casualty and deprivation at an individual or household level. From a policy perspective, however, a location based model is very useful because it allows us to identify the area-level factors that are associated with casualties. Furthermore, our objective is to disentangle the effect on child casualties of ward characteristics and the dimensions of ward deprivation.

The paper is structured as follows. Section 2 describes the deprivation indices. Section 3 develops an area-level model to examine the incidence of child pedestrian casualties. Section 4 discusses issues of model fit and estimation. Results from cross-sectional negative binomial GLMs are presented in Section 5. Conclusions are given in Section 6.