title: NASS-CDS analysis of high retention seat performance in rear impacts.
abstract: OBJECTIVE
  A recent study used the Fatality Analysis Reporting System (FARS) to determine the safety performance of high retention seats in fatal rear impacts. The odds of fatal injury were reduced 46.3% (95% confidence interval [CI], 39.3-52.4, z = 9.982, P <.0001) with high retention seats. This study extends the earlier one by establishing an exposure group of nonfatal occupants in towaway crashes using NASS-CDS.
  
  
  METHODS
  The 2001-2008 NASS-CDS was analyzed for rear impacts of 1992 to 2008 model year GM vehicles with high retention or baseline seats using the same search strategy as in FARS. Injuries were analyzed by severity (Maximum Abbreviated Injury Scale [MAIS]). The number of fatalities from FARS and number of nonfatal occupants from NASS-CDS were used to determine the risk for fatal injury in towaway crashes with 5-7 o'clock principal direction of force (PDOF). The odds ratio for fatal injury and the change in fatality risk were determined with ±95% confidence intervals, z-statistics, and significance levels. Injury risks were also determined using NASS-CDS.
  
  
  RESULTS
  Based on 2001-2008 FARS and NASS-CDS, the fatality risk was 0.21% in high retention seats and 0.39% in baseline seats in 5-7 o'clock towaway crashes. The odds for fatality were 46.8% (95% CI, 39.8-53.0, z = 10.001, P <.0001) lower with high retention seats. There was a higher trend for lower serious-to-critical injury in high retention seats than baseline seats in NASS-CDS. Six electronic cases were available in NASS-CDS with fatal injury in high retention seats. Only one involved the seat performance as a factor in the fatality, a 72-year-old belted female in a 14 mph rear delta V impact who experienced fractures of the thoracic spine. Her upper body likely wrapped around the upright seatback.
  
  
  CONCLUSIONS
  High retention seats significantly reduced the odds for fatal injury in towaway crashes with 5-7 o'clock PDOF. There was a trend for lower serious-to-critical injury risks, but more data are needed to determine significant differences.
authors.affiliation: a ProBiomechanics LLC , Bloomfield Hills , Michigan.
authors.forename: David C
authors.initials: DC
authors.lastname: Viano
authors.forename: Chantal S
authors.initials: CS
authors.lastname: Parenteau
mesh_terms: D015998:Abbreviated Injury Scale; D000063:Accidents, Traffic / Q000401:mortality* / Q000706:statistics & numerical data*; D000328:Adult; D000368:Aged; D016208:Databases, Factual; D005260:Female; D006801:Humans; D008297:Male; D011482:Protective Devices; D014947:Wounds and Injuries / Q000401:mortality* / Q000517:prevention & control*; D055815:Young Adult
keywords: fatalities; injury risks; rear crashes; seats