title: Effectiveness of automatic shoulder belt systems in motor vehicle crashes.
abstract: BACKGROUND
  Approximately 10 million cars with automatic shoulder belt systems are currently in use in the United States. However, reports on the effectiveness of such restraints have yielded conflicting results.
  
  
  OBJECTIVE
  To determine the effectiveness of automatic shoulder belt systems in reducing the risk of injury and death among front-seat passenger vehicle occupants.
  
  
  METHODS
  Analysis of data collected from the 1993-1996 National Highway Traffic Safety Administration Crashworthiness Data System on front-seat occupants involved in 25,811 tow-away crashes of passenger cars, light trucks, vans, and sport utility vehicles.
  
  
  METHODS
  Death and serious injury to specific body areas by use of manual lap and shoulder belts, automatic shoulder belts with manual lap belts, or automatic shoulder belts without lap belts, compared with no restraint use.
  
  
  RESULTS
  Use of automatic shoulder belts without lap belts was associated with a decrease in the risk of death vs no restraint use but was not statistically significant for all crashes (odds ratio [OR], 0.66; 95% confidence interval [CI], 0.42-1.06) or for frontal crashes (OR, 0.71; 95% CI, 0.38-1.35) after adjustment for occupant age, sex, vehicle year, air-bag deployment, estimated change in vehicle speed during the crash, and principal direction of force. This association was significantly weaker than the 86% lower risk observed for use of automatic shoulder belts with lap belts (OR, 0.14; 95% CI, 0.07-0.26 vs no restraint; P<.05). Use of automatic shoulder belts without lap belts was associated with an increased risk of serious chest (OR, 2.66; 95% CI, 1.11-6.35) and abdominal (OR, 2.06; 95% CI, 1.004-4.22) injuries for all crashes.
  
  
  CONCLUSIONS
  These data indicate that improperly used automatic restraint systems may be less effective than properly used systems and are associated with an increased risk of serious chest and abdominal injuries. Given the continued widespread use of these automatic systems, educational programs may be warranted. JAMA. 2000;283:2826-2828
authors.affiliation: Harborview Injury Prevention and Research Center, Box 359960, 325 Ninth Ave, Seattle, WA 98104. fpr@u.washington.edu
authors.forename: F P
authors.initials: FP
authors.lastname: Rivara
authors.forename: T D
authors.initials: TD
authors.lastname: Koepsell
authors.forename: D C
authors.initials: DC
authors.lastname: Grossman
authors.forename: C
authors.initials: C
authors.lastname: Mock
mesh_terms: D000007:Abdominal Injuries / Q000453:epidemiology / Q000517:prevention & control; D000063:Accidents, Traffic / Q000401:mortality / Q000706:statistics & numerical data*; D000328:Adult; D006259:Craniocerebral Trauma / Q000453:epidemiology / Q000517:prevention & control; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D012622:Seat Belts / Q000706:statistics & numerical data*; D013898:Thoracic Injuries / Q000453:epidemiology / Q000517:prevention & control; D014947:Wounds and Injuries / Q000453:epidemiology / Q000517:prevention & control*