Update on the Effectiveness of High Retention Seats in Preventing Fatal Injury in Rear Impacts

ABSTRACT<b>Purpose:</b> Starting in 1997, General Motors (GM) introduced high retention seats in new model vehicles to improve rear impact safety. The seat allowed the occupant to pocket into the seatback; and, it had increased strength and improved head restraint coverage. The initial 4 year safety trends were evaluated using 1991-2000 FARS. The reduction in odds of fatal injury was 30.4% (0.9%-51.1% 95% CI, p &lt;0.05). This study updates the earlier one by adding 8 years of FARS data.<b>Methods:</b> The 2001-2008 FARS was analyzed for rear impacts of 1992 to 2008 model year GM vehicles that transitioned to high retention seats. The number of fatal and non-fatal injuries to drivers and right-front passengers was determined in vehicles with baseline (earlier designs) and high retention seats. The odds ratio for fatal injury and the change in fatality risk were determined with ±95% CI (confidence intervals), z-statistic and significance level. The data was further subdivided by passenger car, light truck (truck, SUV and van) and driver-only crashes.<b>Results:</b> Based on 9,570 drivers and right-front passengers in fatal rear impacts in 1991-2008 FARS data, the fatality risk was 16.6% (15.1%-18.3% 95% CI) in vehicles with high retention seats and 27.1% (26.1%-28.1% 95% CI) in vehicles with baseline seats. The reduction in odds for fatal injury was 46.3% (39.3%-52.4% 95% CI) with high retention seats and it was statistically significant with z = 9.982, p &lt; 0.0001. The reduction in odds for fatal injury was similar for occupants in passenger cars at 45.4% (35.4%-53.8% 95% CI) and light trucks, SUVs and vans at 45.0% (28.8%-57.5% 95% CI) using 2001-2008 FARS; however, the fatality risk was higher in passenger cars at 23.1% (20.6%-25.7% 95% CI) than in light trucks, SUVs and vans at 8.7% (7.0%-10.7% 95% CI).<b>Conclusions:</b> Vehicles with high retention seats significantly reduced the odds for fatal injury by 46.3% (39.3%-52.4% 95% CI, p &lt; 0.0001) in rear impacts compared to vehicles with earlier seat designs. The new generation of yielding seats has significantly improved occupant safety in rear impacts.

**摘要**
**目的**：自1997年起，通用汽车（General Motors，GM）在新款车型中搭载高保持力座椅（high retention seats），以提升追尾碰撞安全性能。该座椅可使乘员贴合嵌入座椅靠背，同时提升了结构强度并优化了头枕覆盖范围。本研究早期依托1991-2000年死亡事故分析报告系统（Fatality Analysis Reporting System，FARS）数据，对最初四年的安全趋势进行了评估，结果显示致命损伤发生几率降低了30.4%（95%置信区间[CI]为0.9%~51.1%，p<0.05）。本研究通过补充8年的FARS数据，对前述研究进行了更新。

**方法**：本研究针对2001-2008年的FARS数据展开分析，分析对象为1992至2008款车型、换装高保持力座椅的通用汽车车辆的追尾碰撞事件。研究统计了搭载基础款（早期设计）座椅与高保持力座椅的车辆中，驾驶员及前排右侧乘员的致死性与非致死性损伤例数。研究计算了致死性损伤的比值比、致死风险变化值，并给出了95%置信区间（confidence intervals，CI）、z统计量与显著性水平。此外，研究还将数据按乘用车、轻型卡车（含普通货车、运动型多用途汽车[SUV]及厢式货车）以及仅涉及驾驶员的碰撞场景进行了细分。

**结果**：基于1991-2008年FARS数据中9570例追尾碰撞致死事件的驾驶员与前排右侧乘员数据，搭载高保持力座椅的车辆致死风险为16.6%（95%CI：15.1%~18.3%），而搭载基础款座椅的车辆致死风险为27.1%（95%CI：26.1%~28.1%）。高保持力座椅可使致命损伤发生几率降低46.3%（95%CI：39.3%~52.4%），且该结果具有统计学显著性（z=9.982，p<0.0001）。基于2001-2008年的FARS数据，乘用车乘员与轻型卡车、SUV及厢式货车乘员的致命损伤发生几率降幅相近，分别为45.4%（95%CI：35.4%~53.8%）与45.0%（95%CI：28.8%~57.5%）；但乘用车的致死风险为23.1%（95%CI：20.6%~25.7%），高于轻型卡车、SUV及厢式货车的8.7%（95%CI：7.0%~10.7%）。

**结论**：与搭载早期座椅设计的车辆相比，搭载高保持力座椅的车辆在追尾碰撞中可使致命损伤发生几率显著降低46.3%（95%CI：39.3%~52.4%，p<0.0001）。新一代高保持力座椅已显著提升了追尾碰撞场景下的乘员安全防护水平。