County Poverty Concentration and Disparities in Unintentional Injury Deaths: A Fourteen-Year Analysis of 1.6 Million U.S. Fatalities

Unintentional injury is the fourth leading cause of death in the United States, and mortality due to injury has risen over the past decade. The social determinants behind these rising trends have not been well documented. This study examines the relationship between county-level poverty and unintentional injury mortality in the United States from 1999–2012. Complete annual compressed mortality and population data for 1999–2012 were obtained from the National Center for Health Statistics and linked with census yearly county poverty measures. The outcomes examined were unintentional injury fatalities, overall and by six specific mechanisms: motor vehicle collisions, falls, accidental discharge of firearms, drowning, exposure to smoke or fire, and unintentional poisoning. Age-adjusted mortality rates and time trends for county poverty categories were calculated, and multivariate negative binomial regression was used to determine changes over time in both the relative risk of living in high poverty concentration areas and the population attributable fraction. Age-adjusted mortality rates for counties with > 20% poverty were 66% higher mortality in 1999 compared with counties with < 5% poverty (45.25 vs. 27.24 per 100,000; 95% CI for rate difference 15.57,20.46), and that gap widened in 2012 to 79% (44.54 vs. 24.93; 95% CI for rate difference 17.13,22.09). The relative risk of living in the highest poverty counties has increased for all injury mechanisms with the exception of accidental discharge of firearms. The population attributable fraction for all unintentional injuries rose from 0.22 (95% CI 0.13,0.30) in 1999 to 0.35 (95% CI 0.22,0.45) in 2012. This is the first study that uses comprehensive mortality data to document the associations between county poverty and injury mortality rates for the entire US population over a 14 year period. This study suggests that injury reduction interventions should focus on areas of high or increasing poverty.

意外伤害是美国第四大死因，过去十年间因伤害导致的死亡率有所上升。这些上升趋势背后的社会决定因素尚未得到充分记录。本研究旨在探讨1999年至2012年间美国县级行政区域内贫困程度与意外伤害死亡率之间的关系。1999年至2012年完整的年度压缩死亡率及人口数据从国家健康统计中心获取，并与年度县贫困指数相联系。所研究的结局包括意外伤害死亡人数，总体上以及由六种特定机制导致的死亡：机动车碰撞、跌落、枪械意外发射、溺水、暴露于烟雾或火焰中以及意外中毒。计算了按年龄调整的死亡率以及县贫困类别的时序趋势，并使用多元负二项回归分析确定相对风险和归因人口分数随时间的变化。1999年，贫困率超过20%的县的按年龄调整死亡率比贫困率低于5%的县高66%（每10万人中有45.25人比27.24人；95%置信区间为15.57至20.46），这一差距在2012年扩大至79%（每10万人中有44.54人比24.93人；95%置信区间为17.13至22.09）。除枪械意外发射外，所有伤害机制的居住在最高贫困县的风险相对值均有增加。所有意外伤害的归因人口分数从1999年的0.22（95%置信区间为0.13至0.30）上升到2012年的0.35（95%置信区间为0.22至0.45）。这是首项使用全面死亡率数据记录县贫困程度与全美人口意外伤害死亡率之间关联性的研究，覆盖了14年的时段。本研究指出，伤害减少干预措施应聚焦于贫困程度高或持续增加的地区。