Hameed Syed Morad, Bell Nathaniel, Schuurman Nadine
Open Med. 2010;4(4):e171-80. Epub 2010 Oct 5.
Recent studies have shown that the morbidity and mortality associated with injury of pedestrians are inversely related to socio-economic status (SES). However, in drawing inferences from this association, investigators have paid little attention to the modifiable artifacts related to scale and how the data are partitioned. The purpose of this population-based study was to identify the relation between SES and incidence patterns of pedestrian injury at 4 different geographic scales.
We used a Poisson generalized linear model, stratified by age and sex, to analyze the relation between each of 4 area measures of SES and incidence patterns of pedestrian injuries occurring in metropolitan Vancouver between 1 January 2001 and 31 March 2006. The 4 area measures of SES were based on boundaries of dissemination areas, census tracts, custom-defined census tracts (generated by reassignment of dissemination area boundaries by means of a geographic information system) and census subdivisions of the Canadian census. We measured the SES of the location where the injury occurred with the Vancouver Area Neighbourhood Deprivation Index.
A total of 262 injuries in adults (18 years of age or older) were analyzed. Among adult men, the odds ratio (OR) for injury of pedestrians at the scale of dissemination area was 4.93 (95% confidence interval [CI] 2.89-8.42) for areas having the lowest SES relative to those with the highest SES. For the same population, the OR for injury was lower with increasing aggregation of data: 2.33 (95% CI 1.45-3.74) when census tracts were used, 3.26 (95% CI 2.06-5.16) when modified census tracts were used and 1.27 (95% CI 0.47-3.45) when census subdivisions were used. Among adult women, the OR for pedestrian injury by SES was highest at the scale of census subdivision within medium-low SES areas (4.33, 95% CI 1.23-15.22). At the census subdivision scale, the relation between SES and incidence pattern of injury was not consistent with findings at smaller geographic scales, and the OR for injury decreased with each increase in SES.
In this analysis, there was significant variability when different administrative boundaries were applied as proxy measures of the effects of place on incidence patterns of injury. The hypothesized influence of SES on prevalence of pedestrian injury followed a statistically significant socio-economic gradient when analyzed using small-area boundaries of the census. However, researchers should be aware of the inherent variability that remains even among the more homogenous population units.
近期研究表明，行人受伤相关的发病率和死亡率与社会经济地位（SES）呈负相关。然而，在从这种关联中得出推论时，研究人员很少关注与规模以及数据划分方式相关的可修正因素。这项基于人群的研究旨在确定SES与4种不同地理尺度下行人受伤发病率模式之间的关系。
我们使用按年龄和性别分层的泊松广义线性模型，分析2001年1月1日至2006年3月31日期间在大温哥华地区发生的行人受伤发病率模式与4种SES区域测量指标之间的关系。这4种SES区域测量指标基于传播区域、普查区、自定义普查区（通过地理信息系统重新分配传播区域边界生成）以及加拿大人口普查的普查分区边界。我们用温哥华地区邻里贫困指数来衡量受伤发生地点的SES水平。
共分析了262例成人（18岁及以上）受伤案例。在成年男性中，相对于SES最高的地区而言，SES最低地区在传播区域尺度下行人受伤的优势比（OR）为4.93（95%置信区间[CI]2.89 - 8.42）。对于同一人群，随着数据聚合程度增加受伤的OR值降低：使用普查区时为2.33（95%CI 1.45 - 3.74），使用修正普查区时为3.26（95%CI 2.06 - 5.16），使用普查分区时为1.27（95%CI 0.47 - 3.45）。在成年女性中，中低SES区域内普查分区尺度下按SES划分的行人受伤OR值最高（4.33，95%CI 1.23 - 15.22）。在普查分区尺度下，SES与受伤发病率模式之间的关系与较小地理尺度下的研究结果不一致，且随着SES的每次升高受伤的OR值降低。
在本分析中，当使用不同行政边界作为地点对受伤发病率模式影响的替代指标时存在显著差异。在使用人口普查的小区域边界进行分析时，SES对行人受伤患病率的假定影响呈现出具有统计学意义的社会经济梯度。然而，研究人员应意识到即使在更同质化的人口单位中仍存在的固有差异。
