Trends in stimulant use in Australia: A comparison of wastewater analysis and population surveys

Levels of community drug use are usually described by national surveys; data relied upon by decision makers in health and law enforcement. In recent years the analysis of wastewater for drugs and their metabolites has become prominent. Both methods convey unique drug use information. This paper demonstrates differences arising from the two approaches, using methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA) and cocaine data from the state of South Australia. The proportion of people using each drug, obtained from three prominent drug surveys, was compared with estimates of total community drug use derived by wastewater analysis. Temporal trends were compared for available years of the surveys and wastewater analysis from 2010 to 2013. Wastewater results showed methamphetamine to be the most prevalent stimulant in Adelaide, South Australia, with an average of 24.4±1.7 doses per day per 1000 inhabitants for 2013, while consumption of MDMA and cocaine were much lower at 0.52±0.12 and 0.42±0.06 doses per day per 1000 inhabitants, respectively. Survey data typically had MDMA as the most used stimulant on a proportion of the population basis. The difference in magnitude of drug use between MDMA and methamphetamine was also less apparent. Temporal trends of the proportion of the population using a drug by surveys did not generally reflect total use within the community which was observed by wastewater analysis. Survey data are excellent for describing users demographically. However, discrepancies between the proportion of the population who are users and the magnitude of drug use can lead to misrepresentation of the overall scale of use. The results from this study indicate methamphetamine was used to a much greater extent than suggested by the surveys. Together, wastewater analysis and survey data give a comprehensive view of the drug problem enabling more informed decisions on drug policy.