Change in alcohol outlet density and alcohol-related harm to population health (CHALICE): a comprehensive record-linked database study in Wales

Excess alcohol consumption has many adverse effects on health, including an increased risk of liver cirrhosis, gastrointestinal tract and breast cancers, high blood pressure and stroke. There is also an increased risk of harm resulting from antisocial behaviour and violence. Binge drinking is a particular problem, with the highest prevalence in the 16- to 24-year age group for women and men. Up to 40% of attendances at accident and emergency (A&E) departments and around half of all violent crimes in the UK are alcohol related. Around 37% of men and 25% of women exceeded UK guidelines for safe levels of alcohol consumption in 2014 (women more than three units per day; men more than four units per day) and 19% of men and 11% of women binge drink (women more than six units per day; men more than eight units per day). Given the wide range of harm resulting from this substantial level of excess consumption, the potential impact on health at the population level from a reduction in consumption is considerable. One of the principal policies recommended by the British Medical Association to reduce alcohol consumption is to reduce easy access to alcohol through controls on hours of sale and outlet density. This uses the availability theory of alcohol-related harm, which states that harmful outcomes are linked directly or indirectly to a greater availability of alcohol, through a higher density of alcohol outlets, leading to higher consumption and hence alcohol-related harm. However, the evidence relating outlet density to alcohol-related harm is not consistent. Many cross-sectional studies have suggested that high outlet densities are associated with a higher rate of a wide range of alcohol-related injuries. Fewer studies have investigated associations between outlet density and non-injury health outcomes, suggesting that high outlet densities are associated with high levels of consumption, sexually transmitted infections and alcohol-related hospital admissions. There have been few longitudinal studies but these have provided limited evidence that an increase in outlet density is associated with increased consumption and interpersonal violence and that a decrease in proximity to outlets is associated with a small decrease in consumption. No longitudinal studies of admissions to hospital have been published for non-violent outcomes. Many methodological questions remain over the best way to measure outlet density and how to model the relationship with alcohol-related harms. Little is known about the effects of a change in outlet density on inequalities in alcohol-related health and the role of population migration