This project was undertaken to provide a detailed understanding of the interface between the price of drugs
and the behaviour of people who inject drugs (PWID) and other drug-market changes. Specifically, three major
aims were to:
1.understand the drug purchase patterns of a large cohort of PWID, and how these change over time;
2.understand how price relates to drug use and drug preferences; and
3.determine the likely effects of changes in drug prices on PWID.
Data on drug purchases and drug use were obtained from the Melbourne Injecting Drug User Cohort Study
(MIX). MIX is a prospective cohort study of young PWID who were recruited between April 2008 and January
2010. Individuals were eligible for the study if they reported being aged between 18 and 30 years old and had
injected either heroin or methamphetamine at least six times in the previous six months.
Data on drug purity were obtained from the Victoria Police Forensic Services Department (VPFSD) so that
price, purity and purity-adjusted price time series could be created for heroin, powder methamphetamine
and crystal methamphetamine. Trends in purchase and use patterns were analysed for heroin, powder
methamphetamine and crystal methamphetamine. Where sufficient observations were available, trends for the
illicit use of benzodiazepines and other opioids were also examined.