title: Minimum purchasing age for alcohol and traffic crash injuries among 15- to 19-year-olds in New Zealand.
abstract: OBJECTIVE
  In 1999, New Zealand lowered the minimum purchasing age for alcohol from 20 to 18 years. We tested the hypothesis that this increased traffic crash injuries among 15- to 19-year-olds.
  
  
  METHODS
  Poisson regression was used to compute incidence rate ratios for the after to before incidence of alcohol-involved crashes and hospitalized injuries among 18- to 19-year-olds and 15- to 17-year-olds (20- to 24-year-olds were the reference).
  
  
  RESULTS
  Among young men, the ratio of the alcohol-involved crash rate after the law change to the period before was 12% larger (95% confidence interval [CI]=1.00, 1.25) for 18- to 19-year-olds and 14% larger (95% CI=1.01, 1.30) for 15- to 17-year-olds, relative to 20- to 24-year-olds. Among young women, the equivalent ratios were 51% larger (95% CI=1.17, 1.94) for 18- to 19-year-olds and 24% larger (95% CI=0.96, 1.59) for 15- to 17-year-olds. A similar pattern was observed for hospitalized injuries.
  
  
  CONCLUSIONS
  Significantly more alcohol-involved crashes occurred among 15-to 19-year-olds than would have occurred had the purchase age not been reduced to 18 years. The effect size for 18- to 19-year-olds is remarkable given the legal exceptions to the pre-1999 law and its poor enforcement.
authors.affiliation: University of Newcastle, 2 Edison St, Adamstown Heights, NSW 2289 Australia. kypri@tpg.com.au
authors.forename: Kypros
authors.initials: K
authors.lastname: Kypri
authors.forename: Robert B
authors.initials: RB
authors.lastname: Voas
authors.forename: John D
authors.initials: JD
authors.lastname: Langley
authors.forename: Shaun C R
authors.initials: SC
authors.lastname: Stephenson
authors.forename: Dorothy J
authors.initials: DJ
authors.lastname: Begg
authors.forename: A Scott
authors.initials: AS
authors.lastname: Tippetts
authors.forename: Gabrielle S
authors.initials: GS
authors.lastname: Davie
mesh_terms: D000063:Accidents, Traffic / Q000706:statistics & numerical data*; D000293:Adolescent; D000294:Adolescent Behavior; D000328:Adult; D000428:Alcohol Drinking / Q000331:legislation & jurisprudence*; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D009520:New Zealand / Q000453:epidemiology