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

Objective: 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). Methods: 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). Results: 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. Conclusions: 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.

研究背景与目的：随着车辆安全技术与评价规程的不断演进，定期评估损伤趋势以明确持续存在及新兴的干预优先级具有重要意义。本研究依托美国国家事故抽样系统-碰撞数据系统（National Accident Sampling System-Crashworthiness Data System, NASS-CDS）1998-2015年的数据集，针对碰撞角度为10点钟至2点钟方位的正面汽车碰撞场景中佩戴安全带的乘员，详细分析了其损伤分布特征与损伤风险变化趋势。
研究方法：首先按乘员年龄与车辆车型年（以2009年为界分为前后两个阶段）进行分层，分析损伤分布特征；随后构建逻辑回归模型，在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）、车辆车型年（仍以2009年为界分层）等变量的前提下，探究各类因素对不同身体区域损伤风险的影响。
研究结果：多项分析表明，与老旧车型相比，2009年及之后款型的新车（车型年[MY]2009及以后）的简略损伤量表（Abbreviated Injury Scale, AIS）2级及以上、3级及以上损伤风险更低，对应优势比分别为0.69（AIS 2+）与0.45（AIS 3+）。新旧车型在损伤风险上的最大降幅出现在下肢区域与颅骨骨折风险维度。不同车型年组别间，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变化。女性乘员的AIS 2+及AIS 3+损伤风险均高于男性，且在多数损伤类型中风险均有所提升。
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实现显著降低。但胸部区域的损伤风险改善进度滞后于其他身体区域，导致新款车型（尤其针对老年乘员）中骨骼损伤的占比有所上升。此外，所有研究年龄段的乘员仍普遍存在手臂、手部/腕部损伤。本研究结果可为车辆乘员保护领域的技术进展成效提供参考，并明确了仍需优化的损伤类型与防控方向。