Mortality Risk in Pediatric Motor Vehicle Crash Occupants: Accounting for Developmental Stage and Challenging Abbreviated Injury Scale Metrics

<b>Objective:</b> Survival risk ratios (SRRs) and their probabilistic counterpart, mortality risk ratios (MRRs), have been shown to be at odds with Abbreviated Injury Scale (AIS) severity scores for particular injuries in adults. SRRs have been validated for pediatrics but have not been studied within the context of pediatric age stratifications. We hypothesized that children with similar motor vehicle crash (MVC) injuries may have different mortality risks (MR) based upon developmental stage and that these MRs may not correlate with AIS severity.<b>Methods:</b> The NASS-CDS 2000–2011 was used to define the top 95% most common AIS 2+ injuries among MVC occupants in 4 age groups: 0–4, 5–9, 10–14, and 15–18 years. Next, the National Trauma Databank 2002–2011 was used to calculate the MR (proportion of those dying with an injury to those sustaining the injury) and the co-injury-adjusted MR (MR_MAIS) for each injury within 6 age groups: 0–4, 5–9, 10–14, 15–18, 0–18, and 19+ years. MR differences were evaluated between age groups aggregately, between age groups based upon anatomic injury patterns and between age groups on an individual injury level using nonparametric Wilcoxon tests and chi-square or Fisher's exact tests as appropriate. Correlation between AIS and MR within each age group was also evaluated.<b>Results:</b> MR and MR_MAIS distributions of the most common AIS 2+ injuries were right skewed. Aggregate MR of these most common injuries varied between the age groups, with 5- to 9-year-old and 10- to 14-year-old children having the lowest MRs and 0- to 4-year-old and 15- to 18-year-old children and adults having the highest MRs (all <i>P</i> MAIS ranging from 0 to 6% and 0 to 4.5%, respectively. Injuries to particular body regions also varied with respect to MR based upon age. For example, thoracic injuries in adults had significantly higher MR_MAIS than such injuries among 5- to 9-year-olds and 10- to 14-year-olds (<i>P</i> =.04; <i>P</i> MAIS in 0- to 18-year-olds was 0.4% for an AIS 3 radius fracture versus 1.4% for an AIS 2 vault fracture.<b>Conclusions:</b> Trauma severity metrics are important for outcome prediction models and can be used in pediatric triage algorithms and other injury research. Trauma severity may vary for similar injuries based upon developmental stage, and this difference should be reflected in severity metrics. The MR-based data-driven determination of injury severity in pediatric occupants of different age cohorts provides a supplement or an alternative to AIS severity classification for pediatric occupants in MVCs.

研究目的：已有研究表明，成人特定损伤的生存风险比（Survival Risk Ratios, SRRs）及其概率对应指标——死亡风险比（Mortality Risk Ratios, MRRs），与简明损伤定级标准（Abbreviated Injury Scale, AIS）损伤严重度评分存在不一致。生存风险比已在儿科人群中完成验证，但尚未针对儿科年龄分层开展相关研究。本研究提出假设：即便遭受相似的机动车碰撞（Motor Vehicle Crash, MVC）损伤，不同发育阶段的儿童其死亡风险（Mortality Risk, MR）或存在差异，且此类死亡风险或与简明损伤定级标准评分无明显相关性。研究方法：本研究采用国家汽车采样系统碰撞数据系统（National Automotive Sampling System Crashworthiness Data System, NASS-CDS）2000-2011年数据集，筛选4个年龄组（0~4岁、5~9岁、10~14岁及15~18岁）机动车碰撞乘员中占比前95%的AIS 2+级损伤。随后，使用国家创伤数据库（National Trauma Databank, NTDB）2002-2011年数据集，针对6个年龄组（0~4岁、5~9岁、10~14岁、15~18岁、0~18岁及19岁以上人群）的每一类损伤，计算其死亡风险（MR，即损伤后死亡人数与损伤总人数的占比）及合并损伤校正死亡风险（MR_MAIS）。本研究分别采用非参数Wilcoxon检验、卡方检验或Fisher确切概率法（根据适配情况选择），从整体年龄组间、基于解剖损伤类型的年龄组间，以及单损伤层面的年龄组间三个维度，对死亡风险的差异进行评估；同时还评估了各年龄组内简明损伤定级标准评分与死亡风险间的相关性。研究结果：占比前95%的AIS 2+级损伤的死亡风险及合并损伤校正死亡风险分布均呈右偏态。此类常见损伤的整体死亡风险在各年龄组间存在显著差异：5~9岁及10~14岁儿童的死亡风险最低，而0~4岁、15~18岁儿童及成人的死亡风险最高（所有组间比较P < 0.001）。单类损伤的合并损伤校正死亡风险分别介于0~6%与0~4.5%之间。不同年龄组间，特定身体区域损伤的死亡风险亦存在差异：例如，成人胸部损伤的合并损伤校正死亡风险显著高于5~9岁及10~14岁儿童（组间比较P=0.04；P < 0.001）。在0~18岁人群中，AIS 3级桡骨骨折的合并损伤校正死亡风险为0.4%，而AIS 2级颅骨穹窿骨折的该指标为1.4%。研究结论：损伤严重度评估指标对于预后预测模型至关重要，同时可应用于儿科伤员分诊算法及其他损伤相关研究。同类损伤的严重程度或因发育阶段不同而存在差异，此类差异应纳入损伤严重度评估指标的考量范畴。基于死亡风险的数据驱动型损伤严重度判定方法，可为不同年龄队列的儿科机动车碰撞乘员提供简明损伤定级标准分级的补充方案或替代选择。