(Medical Xpress)—New research from the University of Otago shows that reducing the minimum alcohol purchasing age to 18 in December 1999, was associated with an increase in assaults of 15-19 year-old males in New Zealand.
The study examined characteristics of patients admitted to New Zealand hospitals with assault injuries on weekends four years before, and up to 12 years after, the law change. Researchers compared assault rates among 18-19 year-olds, whose legal access to alcohol increased, and 15-17 year-olds, whose informal access to alcohol probably increased, against 20-21 year-olds, whose access was unaffected by the law change. The research, published in the prestigious American Journal of Public Health, showed that assault rates increased among 15-19 year-old males compared with the older control group. There were no such effects for females.
Lead author Professor Kypros Kypri says "Our previous research and three other studies showed deleterious effects of the 1999 law change on traffic injury and this was consistent with studies of similar law changes in Australia, the USA, and Canada. There had been no such studies of the effects on assault which is an increasingly important problem in New Zealand and other countries that have liberalised access to alcohol among young people."
The 12 years following the law change were split into three 4-year periods and assault rates in each were compared with the four years immediately preceding the law change. Compared with the change seen in 20-21 year-old males, rates increased by a fifth in 18-19 year-old males, and by a quarter in 15-17 year-old males. Among females, the differences between the three age groups over time were not statistically significant.
"A limitation of the study is that there was insufficient statistical power to properly examine the effect of the law change on females. This is partly because the assault rate is so much lower among females than males, but it is also likely that the dynamics of assault are quite different when females are injured," says co-author Professor Jennie Connor.
She added, "While girls and young women are drinking more than ever, they still account for only one in five or six assault hospitalisations. Assault remains predominantly a problem affecting young men and is likely to be contributing to the gender gap in health".
The findings have important implications for public policy. "Increasing the minimum alcohol purchasing age should be considered as a countermeasure for the rising incidence of assault in many middle and high income countries, including New Zealand" says Professor Kypri.
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Kypri K, Davie G, McElduff P, Connor JL, Langley JDL (2014)." Effects of lowering the minimum alcohol purchasing age on weekend" hospitalised assault. American Journal of Public Health, 104(8) 10.2105/AJPH.2014.301889.