Burnet Institute, Centre for Population Health, Melbourne, VIC, Australia.
Addiction. 2015 Jan;110(1):120-8. doi: 10.1111/add.12740. Epub 2014 Oct 23.
Methamphetamine-related harms in Victoria have increased recently in the context of stable or declining use prevalence. We determine how changes in price and purity of methamphetamine compared to other drugs such as heroin may, in part, explain these divergent patterns.
Detailed methamphetamine and heroin purchase price data from 2152 participant interviews from the Melbourne Injecting Drug User cohort study were used to generate drug price series for the period January 2009-June 2013. Data on drug purity from 8818 seizures made within Victoria were used to generate drug purity series during the same period. Purity-adjusted price data for methamphetamine and heroin were obtained for the period 2009-13 by combining the two data sets.
While the average purity of heroin seizures remained consistent and low, the average purity of powder and of crystal methamphetamine seizures increased from 12% [95% confidence interval (CI) = 10-14%] to 37% (95% CI = 20-54%) and 21% (95% CI = 18-23%) to 64% (95% CI = 60-68%), respectively. Crystal methamphetamine purity was bimodal, with observations generally less than 20% or greater than 70%. The average unadjusted price per gram for heroin decreased from $374 (95% CI = $367-381) to $294 (95% CI = $280-308), powder methamphetamine did not change significantly from $252 (95% CI = $233-271), and crystal methamphetamine increased substantially from $464 (95% CI = $416-511) in 2009 to $795 (95% CI = $737-853) in 2011. This increase was offset by an even greater increase in purity, meaning the average purity-adjusted price per gram declined. Furthermore, pure prices of both methamphetamine forms were similar, whereas their unadjusted prices were not. The pure price of heroin fluctuated with no ongoing trends.
Decreases in methamphetamine purity-adjusted price along with the bimodality of crystal methamphetamine purity may account for some of the recent increase in methamphetamine-related harm. For a given amount spent, methamphetamine purchase power has increased and the presence of extreme purity variations may challenge individuals' control of consumption.
在使用流行率稳定或下降的情况下，最近维多利亚州与甲基苯丙胺相关的危害有所增加。我们确定价格和纯度的变化与其他药物（如海洛因）相比，在一定程度上可以解释这些不同的模式。
从墨尔本注射吸毒者队列研究的 2152 名参与者访谈中获得详细的甲基苯丙胺和海洛因购买价格数据，以生成 2009 年 1 月至 2013 年 6 月期间的药物价格系列。在同一时期，使用维多利亚州 8818 次缉获毒品的数据来生成药物纯度系列。通过将两个数据集合并，获得了 2009-13 年期间甲基苯丙胺和海洛因的纯度调整后价格数据。
虽然海洛因缉获物的平均纯度保持不变且较低，但粉末和晶体甲基苯丙胺缉获物的平均纯度分别从 12%（95%置信区间[CI] = 10-14%）增加到 37%（95%CI = 20-54%）和 21%（95%CI = 18-23%）增加到 64%（95%CI = 60-68%）。晶体甲基苯丙胺纯度呈双峰分布，观察值通常小于 20%或大于 70%。每克海洛因的未调整平均价格从 2009 年的 374 美元（95%CI = 367-381 美元）降至 2013 年的 294 美元（95%CI = 280-308 美元），粉末甲基苯丙胺没有显著变化，仍为 252 美元（95%CI = 233-271 美元），而晶体甲基苯丙胺则大幅从 2009 年的 464 美元（95%CI = 416-511 美元）增加到 2011 年的 795 美元（95%CI = 737-853 美元）。这一增长被纯度的更大增长所抵消，这意味着每克甲基苯丙胺的平均纯度调整后价格下降。此外，两种形式的甲基苯丙胺的纯价格波动，没有持续的趋势。
随着甲基苯丙胺纯度调整后价格的下降以及晶体甲基苯丙胺纯度的双峰分布，可能导致最近与甲基苯丙胺相关的危害有所增加。对于给定的支出金额，购买甲基苯丙胺的能力有所提高，而极端纯度变化的存在可能会挑战个人对消费的控制。
