Trends in treatment episodes for methamphetamine smoking and injecting in Australia, 2003-2019.

INTRODUCTION: We examined trends in Australian treatment episodes for smoking and injecting methamphetamine from 2003 to 2019. METHODS: Data from the Alcohol and Other Drug Treatment National Minimum Data Set, where amphetamines were the principal drug of concern, were analysed from 2003 to 2019. Rates were calculated per 100 000 population aged 10-100 years. Joinpoint software was used to identify changepoints and estimate the annual percentage change (APC) in the rate of treatment episodes. Treatment episode characteristics were compared for smoking versus injecting in 2019. RESULTS: The rate of treatment episodes for methamphetamine increased from 77 to 262 per 100 000 population between 2003 and 2019 (average APC 8%, P < 0.001), this being due to treatment episodes for smoking methamphetamine (average APC 32%, P < 0.001) with no significant increase in treatment episodes for injecting methamphetamine (average APC 3%). Treatment episodes for smoking increased sharply from 2003 to 2008 (APC 72%, P < 0.001) and again from 2010 to 2016 (APC 46%, P < 0.001), this upward trend being attenuated between 2016 and 2019 (APC 7%, P = 0.012). Treatment episodes for methamphetamine smoking (cf. injecting) involved younger clients (median age 30 vs. 35 years, P < 0.001) who were more likely to receive assessment or case management only (37% vs. 29%, P < 0.001). DISCUSSION AND CONCLUSIONS: Increased methamphetamine treatment episodes in Australia since 2003 are due mostly to smoking the drug, this occurring among younger cohort who receive less substantive treatment than clients who inject methamphetamine.