Patterns of polydrug use in Great Britain: Findings from a national household population survey (2011)

Background Polydrug use potentially increases the likelihood of harm. As little is known about polydrug use patterns in the general population, it is difficult to determine patterns associated with highest likelihood.
Methods Latent class analysis was performed on nine illicit substance groups indicating past year use of cannabis, cocaine, amphetamines, ecstasy, LSD, mushrooms, amyl nitrate, tranquillisers and heroin or crack. Analyses were based on data from a large multi-stage probability sample of the population of Great Britain (n = 8538) collected in 2000. Multinomial logistic regression was performed highlighting associations between classes, and demographic and mental health variables.
Results A three class solution best described patterns of polydrug use; wide range, moderate range, and no polydrug use. For males and young people, there was a significantly increased chance of being in the wide and moderate range polydrug use groups compared to the no polydrug use class. Hazardous drinking was more likely in the wide and moderate polydrug classes with odds ratios of 9.99 and 2.38 (respectively) compared to the no polydrug use class. Current smokers were more likely to be wide and moderate range polydrug users compared to the no polydrug use class with odds ratios of 4.53 and 5.85 respectively. A range of mental health variables were also related to class membership.
Conclusions Polydrug use in Great Britain can be expressed as three distinct classes. Hazardous alcohol use and tobacco use were strongly associated with illicit polydrug use, polydrug use appeared to be significantly associated with mental health, particularly lifetime suicide attempts. [Author's abstract]