Abstract
BACKGROUND AND AIMS: Evidence of the effect of limiting off-premises alcohol trading hours is still scarce. This study tested the effect of a small extension in trading hours on alcohol sales in alcohol monopoly outlets in Norway. DESIGN: The extension of trading hours was implemented within a stepped-wedge cluster-randomized trial design. Eligible state monopoly outlets (n = 229) were clustered into trade districts (n = 62), which were block-randomized to one of three sequences regarding date of implementation: 1 September 2020 (n = 21 districts, 82 outlets), 1 December 2020 (n = 21 districts, 73 outlets) and 1 March 2021 (n = 20 districts, 74 outlets). Outcomes were followed-up for a 1-year period. SETTING AND PARTICIPANTS: Study participants were state monopoly outlets in urban and rural trade districts in all parts of Norway. MEASUREMENTS: Monthly alcohol sales in litres of pure alcohol per trade district and per outlet were measured from March 2020 to March 2022 (primary outcome). We applied a linear mixed-effect model with two-way fixed effects within a difference-in-difference framework. As a robustness check we considered the effects of cross-border trade and effects in subgroups of outlets. Trading hours in monopoly outlets were extended by 1 hour on Saturdays. The extension was permanent. Pre-intervention periods and not-yet-treated units served as control conditions. FINDINGS: We did not find a statistically significant effect of the small extension in trading hours on monthly alcohol sales (i) per trade district [average treatment effect: -185.5 litres, 95% confidence interval (CI) = -1159.9, 788.9] and (ii) per outlet (-35.3 litres, 95% CI = -142.1, 72.0). These findings were consistent across estimation methods and model specifications. CONCLUSION: There is no clear evidence that a small extension in off-premises trading hours affected alcohol sales in monopoly outlets in Norway.