Injury patterns in motor vehicle collision–youth pedestrian deaths

The objective of this study was to describe fatal pedestrian injury patterns in youth aged 15 to 24 years old and correlate them with motor vehicle collision (MVC) dynamics and pedestrian kinematics using data from medicolegal death investigations of MVCs occurring in the current Canadian motor vehicle (MV) fleet. Based on a systematic literature review, MVC–pedestrian injuries were collated in an injury data collection form (IDCF). The IDCF was coded using the Abbreviated Injury Scale (AIS) 2015 revision. The AIS of the most frequent severe injury was noted for individual body regions. The Maximum AIS (MAIS) was used to define the most severe injury to the body overall and by body regions (MAISBR). This study focused on serious to maximal injuries (AIS 3–6) that had an increasing likelihood of causing death. The IDCF was used to extract collision and injury data from the Office of the Chief Coroner for Ontario (OCCO) database of postmortem examinations done at the Provincial Forensic Pathology Unit (PFPU) in Toronto, Canada, and other provincial facilities between 2013 and 2019. Injury data were correlated with data about the MVs and MV dynamics and pedestrian kinematics. The study was approved by the Western University Health Science Research Ethics Board (Project ID: 113440; Lawson Health Research Institute Approval No. R-19-066). There were 88 youth, including 54 (61.4%) males and 34 (38.6%) females. Youth pedestrians comprised 13.1% (88/670) of all autopsied pedestrians. Cars (<i>n</i> = 25/88, 28.4%) were the most frequent type of vehicle in single-vehicle impacts, but collectively vehicles with high hood edges (i.e., greater distance between the ground and hood edge) were in the majority. Forward projection (<i>n</i> = 34/88, 38.6%) was the most frequent type of pedestrian kinematics. Regardless of the type of vehicle, there was a tendency in most cases for the median MAISBR ≥ 3 to involve the head and thorax. A similar trend was seen in most of the pedestrian kinematics involving the various frontal impacts. Of the 88 cases, at least 63 (71.6%) were known to be engaged in risk-taking behaviors (e.g., activity on roadway). At least 12 deaths were nonaccidental (8 suicides and 4 homicides). Some activities may have been impairment related, because 26/63 (41.3%) pedestrians undertaking risk-taking behavior on the roadway were impaired. Toxicological analyses revealed that over half of the cases (47/88, 53.4%) tested positive for a drug that could have affected behavior. Ethanol was the most common. Thirty-one had positive blood results. A fatal dyad of head and thorax trauma was observed for pedestrians struck by cars. For those pedestrians hit by vehicles with high hood edges, which were involved in the majority of cases, a fatal triad of injuries to the head, thorax, and abdomen/retroperitoneum was observed. Most deaths occurred from frontal collisions and at speeds more than 35 km/h.

本研究旨在描述15至24岁青年行人的致命损伤模式，并结合当前加拿大机动车（Motor Vehicle, MV）车队中发生的机动车碰撞（Motor Vehicle Collision, MVC）相关动力学数据与行人运动学数据，基于相关法医学死亡调查数据开展关联分析。本研究基于系统文献综述，将MVC相关行人损伤信息整理至损伤数据采集表（Injury Data Collection Form, IDCF）中；该表采用2015版简明损伤定级标准（Abbreviated Injury Scale, AIS）进行编码，针对各身体部位记录了最常见严重损伤的AIS分值，并采用最高简明损伤定级（Maximum AIS, MAIS）分别定义全身及各身体部位的最严重损伤（MAISBR）。本研究聚焦于致死风险随等级升高的严重至极严重损伤（AIS 3~6级）。研究团队通过该损伤数据采集表，从安大略省首席验尸官办公室（Office of the Chief Coroner for Ontario, OCCO）的数据库中提取2013至2019年间，于加拿大多伦多省法医病理科（Provincial Forensic Pathology Unit, PFPU）及其他省级机构完成的尸检相关碰撞与损伤数据，并将损伤数据与机动车、机动车碰撞动力学及行人运动学相关数据进行关联分析。本研究已通过西安大略大学健康科学研究伦理委员会审批（项目编号：113440；劳森健康研究所审批编号：R-19-066）。本研究共纳入88名青年行人，其中男性54例（占比61.4%），女性34例（占比38.6%）；该群体占所有接受尸检的行人总数的13.1%（88/670）。在单车碰撞事故中，轿车（n=25/88，占比28.4%）为最常见的碰撞车辆类型，但整体来看，引擎盖边缘离地高度较高的车辆占多数。前抛运动（n=34/88，占比38.6%）为最常见的行人运动学类型。无论车辆类型如何，大多数案例中中位数MAISBR≥3的损伤多累及头部与胸部；在各类正面碰撞对应的行人运动学场景中，也观察到了相似的损伤累及趋势。在88例案例中，至少63例（占比71.6%）的行人存在冒险行为（如在道路上活动）；至少12例死亡并非意外事故，其中8例为自杀，4例为他杀。部分冒险行为可能与意识受损相关，63例存在道路冒险行为的行人中，有26例（占比41.3%）存在意识受损情况。毒理学分析显示，超过半数案例（47/88，占比53.4%）的行为影响类药物检测呈阳性，其中最常见的物质为乙醇，共31例血液乙醇检测结果呈阳性。被轿车撞击的行人中，观察到头部与胸部创伤构成的致命损伤二元组合；对于占多数案例的引擎盖边缘离地高度较高的车辆撞击的行人，观察到头部、胸部及腹部/腹膜后腔创伤构成的致命损伤三元组合。大多数死亡案例发生于正面碰撞且碰撞车速超过35km/h的场景中。