Citation

Kypri K, Voas RB, Langley JD, Stephenson SC, Begg DJ, Tippetts AS, Davie GS. Am. J. Public Health 2005; 96(1): 126-131.

Affiliation

University of Newcastle.

Copyright

(Copyright © 2005, American Public Health Association)

DOI

10.2105/AJPH.2005.073122

PMID

16317197

PMCID

PMC1470436

Abstract

Objectives. In 1999, New Zealand lowered the minimum purchasing age for alcohol from 20 to 18. 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 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-yearolds, relative to 20- to 24-year-olds. Among 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. The effect size for 18- to 19-year-olds is remarkable given the legal exceptions to the pre-1999 law and its poor enforcement.