Who uses multiple drugs together, and what are the patterns? A population study in Great Britain

What is it about?

Polydrug use, the concurrent or sequential use of multiple substances, carries greater potential for harm than single-substance use, yet patterns of polydrug use in the general population were poorly understood at the time of this study. Using data from a national household population survey in Great Britain, the study applied latent class analysis to self-reported past-year use of nine illicit substance groups including cannabis, cocaine, amphetamines, ecstasy, LSD, mushrooms, amyl nitrate, tranquillisers and heroin or crack cocaine. Latent class analysis is a statistical technique that identifies distinct subgroups within a population based on their patterns of responses, revealing which combinations of substances tend to cluster together across different groups of people. The analysis identified distinct polydrug use profiles in the general population and characterised the demographic and substance-use characteristics of each class, establishing which patterns of multi-substance use are most prevalent and which are associated with the highest likelihood of harm.

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Why is it important?

Understanding polydrug use patterns at a population level is essential for designing targeted prevention, harm reduction and treatment responses. Treating all drug users as a homogeneous group fails to capture the very different risk profiles and intervention needs of, for example, recreational stimulant users compared with people using heroin alongside tranquillisers. This paper was among the first to apply latent class analysis to national polydrug use data in a Great Britain context, demonstrating the value of data-driven statistical approaches for segmenting substance use populations in ways that are clinically and policy-relevant.