Table 1 Data sources investigated to inform estimates of people who inject drugs in Australia

New South Wales-specific datasets

Pharmaceutical Drugs of Addiction System

Number of people in opioid substitution therapy at July 1, 2014 (also available from National Opioid Pharmacotherapy Statistics Annual Data Collection)

Multiplier data available from Australian Needle and Syringe Program Survey

Needle and Syringe Program data

Number of needles and syringes distributed by public needle and syringe programs and pharmacies in NSW, 2014

Data related to number of needle and syringe units distributed rather than individuals accessing needles and syringes. A two-step estimation process that used published data to construct a benchmark number of people accessing needle and syringe programs, followed by standard multiplier method, produced implausibly low estimates

Re-offending Database

Number of persons proceeded against for use/possess amphetamine, cocaine or narcotics, 2014

Unable to identify suitable multiplier (arrested/charged with use/possess amphetamine, cocaine or opioids in the previous 12 months).

New South Wales Ambulance

Number of ambulance attendances where naloxone was administered, 2014

Unable to identify suitable multiplier (had an overdose in the past 12 months where an ambulance attended and administered naloxone). The Illicit Drug Reporting System collects data on treatment responses to overdose, but it was not possible to construct a multiplier referring specifically to ambulance-administered naloxone.

Emergency Department Data Collection

Emergency department presentations for amphetamine, cocaine or opioid overdose, 2014

Unable to identify suitable multiplier (attended an emergency department with amphetamine, cocaine or opioid overdose in the past 12 months)

Admitted Patients Data Collection

Hospital separations for amphetamine, cocaine or opioid overdose, 2014

Unable to identify suitable multiplier (admitted to hospital with amphetamine, cocaine or opioid overdose in the previous 12 months)

National datasets

National Opioid Pharmacotherapy Statistics Annual Data Collection

Number of people in opioid substitution therapy on a snapshot day in Australia and all states and territories, 2014

Multiplier data extracted from Australian Needle and Syringe Program Survey

Australian Bureau of Statistics mortality data

Number of amphetamine-, cocaine- and opioid-induced deaths in Australia and all states and territories, 2014

An increasing proportion of opioid-related deaths in Australia are due to pharmaceutical opioids and may be among people who do not inject drugs; hence there were concerns that the benchmark data may not represent the population of people who inject drugs and use of these data would overestimate people who inject drugs. Mortality data were used for validation and limitations of this are noted in the Discussion.