Implementation of minimum unit pricing for alcohol in Scotland and subsequent rates of hospital-admitted self-harm: controlled interrupted time series analysis

Abstract

BACKGROUND: Harmful alcohol use is a major modifiable risk factor for self-harm. We aimed to examine associations between minimum unit pricing for alcohol, introduced in Scotland in 2018, and rates of hospital-admitted self-harm. METHODS: Data were obtained from Public Health Scotland and English Hospital Episode Statistics. Interrupted time series (ITS) analysis compared pre- and post-intervention self-harm admission rates per 100 000 population, including controlled comparisons with England. RESULTS: The before-after slope reduction in Scotland corresponded to -5.6 (95% CI -7.5 to -3.7) admissions per quarter, per 100 000 population, over the intervention period. Using controlled ITS, a greater slope reduction was observed in Scotland relative to England: -3.5, CI -6.4 to -0.6. No differences in slope change were observed when examining only pre-pandemic study quarters. Findings were consistent with a possible postintervention rate reduction in the two most deprived population quintiles, while no between-nation slope difference was observed in the three least deprived quintiles. CONCLUSIONS: Findings were consistent with possible postintervention reductions in hospital-admitted self-harm in Scotland compared to England, with reductions concentrated in more deprived populations. Population-level alcohol pricing policies may contribute to reducing self-harm frequency, although causal interpretation is limited by the observational, quasi-experimental study design and differing between-nation pre-intervention trajectories.