Objectives Intersectionality is a theoretical concept and tool for critical thought about how disadvantage is experienced within different minority groups, and in particular when people fall into multiple groups and experience increased social oppression as a result. While this school of thought is used frequently in sociological and political arenas, it has not been widely applied in epidemiological context to understand how health behaviours and outcomes are affected when people identify in more than one minority, or socially disadvantaged category. This study aimed to use the theoretical framework of intersectionality to guide and interpret the analysis of the data from a large scale survey looking at substance and alcohol use across different genders, sexualities, and ethnicities. Specifically we aimed to understand whether intersectionality acted as a risk or protective factor when examining alcohol and drug use. Methods The paper analysed data from 92,183 participants within the Global Drug Survey from January 2015. 92.5% of participants are from High Income OECD-member country as defined by the World Bank. Data was analysed to look for differences in ethnic identity, genders, and sexual orientation Results Ethnicity single group odds ratios are higher for five substances and lower for four substances. Intersecting identity shows generally lower odds ratios of lifetime and past year use than single group odds ratios. Intersecting identity (ethnicity and sexual minority) appears to have a protective factor against substance use and health impact of alcohol. Ethnic minorities show generally higher odds ratios (single group comparison) for all substances both lifetime and past year use. Ethnic minority females show higher odds ratios than ethnic majority females for lifetime and past year substance use. Sexual minority single odds ratios are generally higher than those for female (except lifetime alcohol use). Potential protective factors of an intersecting identity of ethnic minority and sexual minority appear to be lower for females than for males. The potential short-term protective factor of sexual minority females decreases drastically for ethnic minority females. Conclusion This study shows the impact of intersecting identities on health risk behaviours as significant and in need of further research to bring a better understanding of behavioural patterns within the most vulnerable groups within society in order to intervene effectively in future
