title: Association Between NCAP Ratings and Real-World Rear Seat Occupant Risk of Injury.
abstract: OBJECTIVE
  Several studies have evaluated the correlation between U.S. or Euro New Car Assessment Program (NCAP) ratings and injury risk to front seat occupants, in particular driver injuries. Conversely, little is known about whether NCAP 5-star ratings predict real-world risk of injury to restrained rear seat occupants. The NHTSA has identified rear seat occupant protection as a specific area under consideration for improvements to its NCAP. In order to inform NHTSA's efforts, we examined how NCAP's current 5-star rating system predicts risk of moderate or greater injury among restrained rear seat occupants in real-world crashes.
  
  
  METHODS
  We identified crash-involved vehicles, model year 2004-2013, in NASS-CDS (2003-2012) with known make and model and nonmissing occupant information. We manually matched these vehicles to their NCAP star ratings using data on make, model, model year, body type, and other identifying information. The resultant linked NASS-CDS and NCAP database was analyzed to examine associations between vehicle ratings and rear seat occupant injury risk; risk to front seat occupants was also estimated for comparison. Data were limited to restrained occupants and occupant injuries were defined as any injury with a maximum Abbreviated Injury Scale (AIS) score of 2 or greater.
  
  
  RESULTS
  We linked 95% of vehicles in NASS-CDS to a specific vehicle in NCAP. The 18,218 vehicles represented an estimated 6 million vehicles with over 9 million occupants. Rear seat passengers accounted for 12.4% of restrained occupants. The risk of injury in all crashes for restrained rear seat occupants was lower in vehicles with a 5-star driver rating in frontal impact tests (1.4%) than with 4 or fewer stars (2.6%, P =.015); results were similar for the frontal impact passenger rating (1.3% vs. 2.4%, P =.024). Conversely, side impact driver and passenger crash tests were not associated with rear seat occupant injury risk (driver test: 1.7% for 5-star vs. 1.8% for 1-4 stars; passenger test: 1.6% for 5 stars vs 1.8% for 1-4 stars).
  
  
  CONCLUSIONS
  Current frontal impact test procedures provide some degree of discrimination in real-world rear seat injury risk among vehicles with 5 compared to fewer than 5 stars. However, there is no evidence that vehicles with a 5-star side impact passenger rating, which is the only crash test procedure to include an anthropomorphic test dummy (ATD) in the rear, demonstrate lower risks of injury in the rear than vehicles with fewer than 5 stars. These results support prioritizing modifications to the NCAP program that specifically evaluate rear seat injury risk to restrained occupants of all ages.
authors.affiliation: a Center for Injury Research and Prevention , The Children's Hospital of Philadelphia , Philadelphia , Pennsylvania.
authors.forename: Kristina B
authors.initials: KB
authors.lastname: Metzger
authors.affiliation: a Center for Injury Research and Prevention , The Children's Hospital of Philadelphia , Philadelphia , Pennsylvania.
authors.forename: Siobhan
authors.initials: S
authors.lastname: Gruschow
authors.affiliation: a Center for Injury Research and Prevention , The Children's Hospital of Philadelphia , Philadelphia , Pennsylvania.|b Department of Pediatrics at the Perelman School of Medicine , University of Pennsylvania , Philadelphia , Pennsylvania.|c Center for Clinical Epidemiology and Biostatistics , Perelman School of Medicine at the University of Pennsylvania , Philadelphia , Pennsylvania.
authors.forename: Dennis R
authors.initials: DR
authors.lastname: Durbin
authors.affiliation: a Center for Injury Research and Prevention , The Children's Hospital of Philadelphia , Philadelphia , Pennsylvania.|c Center for Clinical Epidemiology and Biostatistics , Perelman School of Medicine at the University of Pennsylvania , Philadelphia , Pennsylvania.
authors.forename: Allison E
authors.initials: AE
authors.lastname: Curry
mesh_terms: D015998:Abbreviated Injury Scale; D000063:Accidents, Traffic / Q000706:statistics & numerical data*; D001336:Automobiles / Q000706:statistics & numerical data*; D016208:Databases, Factual; D006801:Humans; D015397:Program Evaluation; D015203:Reproducibility of Results; D012306:Risk; D012449:Safety / Q000592:standards*; D014481:United States; D014947:Wounds and Injuries / Q000209:etiology*
keywords: crash ratings; crash test; motor vehicle crash; motor vehicle safety; occupant protection