Automobile injury trends in the contemporary fleet: Belted occupants in frontal collisions

<b>Objective:</b> As vehicle safety technologies and evaluation procedures advance, it is pertinent to periodically evaluate injury trends to identify continuing and emerging priorities for intervention. This study examined detailed injury distributions and injury risk trends in belted occupants in frontal automobile collisions (10 o’clock to 2 o’clock) using NASS-CDS (1998–2015). <b>Methods:</b> Injury distributions were examined by occupant age and vehicle model year (stratified at pre- and post-2009). Logistic regression models were developed to examine the effects of various factors on injury risk (by body region), controlling for delta-V, sex, age, height, body mass index (BMI), vehicle model year (again stratified at 2009). <b>Results:</b> Among other observations, these analyses indicate that newer model year vehicles (model year [MY] 2009 and later) carry less risk of Abbreviated Injury Scale (AIS) 2+ and AIS 3+ injury compared to older model year vehicles, with odds ratios of 0.69 (AIS 2+) and 0.45 (AIS 3+). The largest reductions in risk between newer model year vehicles and older model year vehicles occur in the lower extremities and in the risk of skull fracture. There is no statistically significant change in risk of AIS 3+ rib fracture or sternum injury between model year categories. Females are at greater risk of AIS 2+ and AIS 3+ injury compared to males, with increased risk across most injury types. <b>Conclusions:</b> For belted occupants in frontal collisions, substantial reductions in injury risk have been realized in many body regions in recent years. Risk reduction in the thorax has lagged other body regions, resulting in increasing prevalence among skeletal injuries in newer model year vehicles (especially in the elderly). Injuries also remain common in the arm and hand/wrist for all age ranges studied. These results provide insight into where advances in the field have made gains in occupant protection and what injury types remain to be addressed.

研究目标：随着车辆安全技术与评价规程的持续迭代，定期评估损伤趋势以识别持续存在及新出现的干预优先级具有重要现实意义。本研究依托国家事故采样系统-碰撞数据系统（NASS-CDS，1998–2015），针对碰撞角度为10时至2时方向的正面汽车碰撞中佩戴安全带的乘员，分析了详细的损伤分布与损伤风险变化趋势。
研究方法：本研究按乘员年龄与车辆生产年份（以2009年为界分为前后两组）对损伤分布进行分层分析。构建逻辑回归模型，通过控制碰撞速度变化量（delta-V）、性别、年龄、身高、身体质量指数（Body Mass Index, BMI）以及车辆生产年份（仍以2009年为界分层）的影响，探究各类因素对不同身体区域损伤风险的作用。
研究结果：除其他观测结果外，分析表明，与老旧车辆相比，2009年及以后生产的新型车辆（车辆生产年份[MY] 2009及以后）的简明损伤定级标准（Abbreviated Injury Scale, AIS）2级及以上和3级及以上损伤风险更低，其优势比分别为0.69（AIS 2+）与0.45（AIS 3+）。新型车辆相较于老旧车辆，损伤风险降幅最为显著的身体区域为下肢，颅骨骨折风险的降低幅度也最为显著。不同生产年份的车辆之间，AIS 3级肋骨骨折或胸骨损伤的风险未出现统计学意义上的显著差异。与男性乘员相比，女性乘员的AIS 2+及AIS 3+损伤风险更高，且多数损伤类型的风险均有所上升。
研究结论：对于正面碰撞中佩戴安全带的乘员而言，近年来多个身体区域的损伤风险已得到显著降低。但胸部损伤风险的改善滞后于其他身体区域，导致新型车辆中（尤其是老年乘员）骨骼损伤的占比有所上升。此外，所有研究覆盖的年龄段中，手臂、手部及腕部损伤仍较为常见。本研究结果可为车辆乘员保护领域的技术进步所带来的成效，以及仍待解决的损伤类型提供参考依据。