title: Long-term effects of lowering the alcohol minimum purchasing age on traffic crash injury rates in New Zealand.
abstract: In December 1999, New Zealand lowered the alcohol minimum purchasing age from 20 to 18 years. We tested hypotheses that this change was associated with long-term increases in traffic injury attributable to alcohol-impaired driving among 18- to 19-year-olds (target age group) and 15- to 17-year-olds (affected by 'trickle-down').
  
  
  
  We undertook a controlled before-and-after comparison of rates of fatal and non-fatal traffic injury to persons of any age attributable to impaired drivers aged 18-19 years and 15-17 years, versus 20- to 21-year-olds. Crash data including assessment of driver alcohol impairment were recorded by New Zealand Police. The pre-change period was 1996-1999. Post-change periods were 2000-2003, 2004-2007 and 2008-2010. Outcomes were population-based and vehicle travel-based rates.
  
  
  
  Compared with the change in injury rates attributable to alcohol-impaired 20- to 21-year-old male drivers, injuries attributable to 18- to 19-year-old male drivers increased in all post-change periods and significantly so in the second post-change period (incidence rate ratio [IRR] 1.3, 95% confidence interval [CI] 1.1 to 1.5). For 15- to 17-year-old male drivers, rates increased in all post-change periods compared with 20- to 21-year-olds, and more so in the second (IRR 1.2, 95% CI 1.1 to 1.4) and third (IRR 1.2, 95% CI 1.1 to 1.4) periods. There was a short-term relative increase in harm attributable to 18- to 19-year-old female drivers (IRR 1.5; 1.1 to 2.0). Results were similar for vehicle travel-based rates.
  
  
  
  Reducing the alcohol minimum purchasing age was followed by long-term increases in the incidence of traffic injury attributable to male 15- to 19-year-old alcohol-impaired drivers. [Kypri K, Davie G, McElduff P, Langley J, Connor J. Long-term effects of lowering the alcohol minimum purchasing age on traffic crash injury rates in New Zealand. Drug Alcohol Rev 2017;36:178-185].
authors.affiliation: School of Medicine and Public Health, University of Newcastle, Newcastle, Australia.|Injury Prevention Research Unit, University of Otago, Dunedin, New Zealand.
authors.forename: Kypros
authors.initials: K
authors.lastname: Kypri
authors.affiliation: Injury Prevention Research Unit, University of Otago, Dunedin, New Zealand.
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Davie
authors.affiliation: School of Medicine and Public Health, University of Newcastle, Newcastle, Australia.
authors.forename: Patrick
authors.initials: P
authors.lastname: McElduff
authors.affiliation: Injury Prevention Research Unit, University of Otago, Dunedin, New Zealand.
authors.forename: John
authors.initials: J
authors.lastname: Langley
authors.affiliation: Department of Preventive and Social Medicine, University of Otago, Dunedin, New Zealand.
authors.forename: Jennie
authors.identifier: 0000-0002-3209-8693
authors.initials: J
authors.lastname: Connor
mesh_terms: D000063:Accidents, Traffic / Q000706:statistics & numerical data*; D000293:Adolescent; D000367:Age Factors; D000428:Alcohol Drinking / Q000453:epidemiology / Q000331:legislation & jurisprudence*; D000434:Alcoholic Beverages / Q000191:economics / Q000600:supply & distribution*; D003132:Commerce / Q000331:legislation & jurisprudence; D000066448:Driving Under the Influence / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D009520:New Zealand / Q000453:epidemiology; D012737:Sex Factors; D013997:Time Factors; D055815:Young Adult
keywords: alcohol; drinking age; minimum purchasing age; traffic injury