Purity-adjusted prices of illicit drugs are related to drug harms. In this study we examined the time series of purity adjusted prices of crystal methamphetamine and heroin between 2009 and 2020 in Victoria, Australia, and whether this varied by rurality. Data on purity of illicit drug seizures by Victoria Police (2009–2020; n = 47,696) were analysed alongside surveys from two prospective cohort studies of people who use drugs in metropolitan and rural Victoria. Heroin and crystal methamphetamine price, purity, and purity-adjusted price were computed for metropolitan Melbourne (2009–2020) and rural Victoria (2016–2020), adjusted for inflation. Initial rises in unadjusted crystal methamphetamine prices in metropolitan Melbourne were offset by increasing purity levels, leading to a decline in the average purity-adjusted price from AUD 1360 per pure gram (PPG) in 2009 to AUD 330 in 2019, after which it stabilised. Similarly, in rural Victoria, purity-adjusted prices declined between 2016 and 2019, followed by an increase, reaching AUD 600 PPG by 2020. Overall, average purity-adjusted prices were significantly higher in rural Victoria compared to metropolitan Melbourne. The average purity-adjusted PPG for heroin in metropolitan Melbourne increased from AUD 1300 PPG in 2009 until 2014, before declining to AUD 770 by 2020. Overall declines in both crystal methamphetamine and heroin purity-adjusted prices in Victoria suggests that, by 2019, people who purchased these drugs received more drug for a given purchase than in previous years. These changes closely match trends seen in some key harms such as opioid overdose.
Dietze et al. (Sat,) studied this question.