title: Young Drivers and Their Passengers: A Systematic Review of Epidemiological Studies on Crash Risk.
abstract: OBJECTIVE
  A systematic review of the literature was conducted to appraise the evidence from epidemiological studies of crash risk in young drivers accompanied by passengers, compared with solo driving.
  
  
  METHODS
  Databases searched were the Cochrane Library, Embase, Scopus, Transportation Research Information Services, and Web of Science for studies published between January 1, 1989 and August 1, 2013. Epidemiological studies were selected for review if they focused on crashes of young drivers (≤24 years old) and included both a no-passenger comparison group and some measure of exposure to enable calculation of estimates.
  
  
  RESULTS
  Fifteen articles (17 studies) were selected; seven studies reported on fatal crashes and 10 on nonfatal or combined fatal/nonfatal crashes. Studies on fatal crashes showed increased risk, compared with solo driving, for young drivers with at least one passenger (significant estimates ranging from 1.24 to 1.89) and two or more passengers versus solo driving (1.70-2.92). Increased risk was also found for fatal crashes and for combined or nonfatal crashes with male versus female passengers (1.53-2.66) and for younger versus older drivers (1.42-3.14).
  
  
  CONCLUSIONS
  Results more clearly indicated an increased risk for passenger presence in fatal crashes than that in nonfatal or combined fatal/nonfatal crashes. Findings of this review, based on correlational studies, support licensing policies that limit the presence and number of young passengers for young drivers.
authors.affiliation: Faculty of Medicine and Health Sciences, Université de Sherbrooke, Longueuil, Quebec, Canada; Charles Lemoyne Hospital Research Centre, Longueuil, Quebec, Canada. Electronic address: marie.claude.ouimet@usherbrooke.ca.
authors.forename: Marie Claude
authors.initials: MC
authors.lastname: Ouimet
authors.affiliation: University of Michigan Transportation Research Institute, Ann Arbor, Michigan.
authors.forename: Anuj K
authors.initials: AK
authors.lastname: Pradhan
authors.affiliation: Department of Community and Behavioral Health, Colorado School of Public Health, University of Colorado Anschutz Medical Campus, Aurora, Colorado.
authors.forename: Ashley
authors.initials: A
authors.lastname: Brooks-Russell
authors.affiliation: Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland.
authors.forename: Johnathon P
authors.initials: JP
authors.lastname: Ehsani
authors.affiliation: Charles Lemoyne Hospital Research Centre, Longueuil, Quebec, Canada.
authors.forename: Djamal
authors.initials: D
authors.lastname: Berbiche
authors.affiliation: Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland.
authors.forename: Bruce G
authors.initials: BG
authors.lastname: Simons-Morton
mesh_terms: D000063:Accidents, Traffic / Q000706:statistics & numerical data*; D000293:Adolescent; D000294:Adolescent Behavior; D001334:Automobile Driving / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D010379:Peer Group; D012307:Risk Factors; D012737:Sex Factors; D055815:Young Adult
keywords: Adolescent; Driver; Passenger; Systematic review; Traffic accident; Young adult