There is a need to ensure public health policies are robustly evaluated to establish their benefits and harms on the population and subgroups. We aimed to assess the comparability of Northern Ireland (NI) and Republic of Ireland (RoI) alcohol-related data to determine their suitability for evaluating the effectiveness of alcohol policies on alcohol consumption, sales, and related outcomes.

A comparability analysis of NI and RoI alcohol-related hospital admissions, deaths, consumption, sales, and crime administrative and survey data was undertaken. Data sources were compared, where applicable, in terms of coding systems, population coverage, definitions, quality, response/completion rates, and question similarity.

The NI and RoI consumption and sales data were found not to be comparable enough for use in a natural experiment study; comparability for hospital admission data was acceptable. Key barriers to comparability included variations in population coverage and lack of overlap in questionnaire topics. Data access issues made it difficult to fully determine data comparability for alcohol-related crime and deaths. By contrast, NI alcohol-related data were more comparable with other UK countries, making comparisons for the purpose of policy evaluation possible. RoI would benefit from identifying another economically and culturally similar country with comparable alcohol-related data.