BACKGROUND: A strict high legal age limit for alcohol purchases decreases adolescents' access to alcohol, but little is known about long-term health effects. The aim was to estimate the effect of increased alcohol availability during adolescence on alcohol-related morbidity and mortality.

METHODS: A nationwide register-based study using data from a natural experiment setting. In two regions of Sweden, strong beer (4.5%-5.6% alcohol by volume) became temporarily available for purchase in grocery stores for individuals 16 years or older (instead of 21) in 1967/1968. The intervention group was defined as all individuals living in the intervention area when they were 14-20 years old (n=72 110). The remaining Swedish counties excluding bordering counties, without the policy change, were used as the control group (n=456 224). The outcomes of alcohol-related morbidity and mortality were collected from the Hospital Discharge Register and Cause of Death Register, in which average follow-up times were 38 years and 41 years, respectively. HRs with 95% CIs were obtained by Cox regression analysis.

RESULTS: In the fully adjusted model, no clear evidence of an association between increased alcohol availability during adolescence and alcohol-related morbidity (HR: 0.99, 95% CI 0.96 to 1.02) or mortality (HR: 1.02, 95% CI 0.95 to 1.10) was found.

CONCLUSION: The initial elevated risk of alcohol-related morbidity and mortality later in life among adolescents exposed to increased access to strong beer in Sweden vanished when a regional measure population density of locality was included in the model, which is important to consider in future research.