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❓ A WA parliamentary question on notice inquires about the estimated number of drug addicts in Western Australia five years prior and the methodology used for calculation. The Minister provides a detailed response outlining two different methodologies used to estimate heroin use.

AnsweredQoN 705Legislative Assembly

Asked

12 September 2000

Member

Dr CONSTABLE

Portfolio

Police

QuestionView source ↗

With reference to information provided during the Estimates Committee in May this year that there are 15,000 to 50,000 heroin addicts in Western Australia, I ask - (a) what was the estimated number of drug addicts in Western Australia five years ago; and (b) how is the estimate calculated? Answered on 20 September 2000 The Minister

AnswerView source ↗

Answered

20 September 2000

Response time

8 days

(a) There have been two methodologies that have been used to estimate the number of heroin users in this State. The first approach that was followed by the Select Committee into the Misuse of Drugs Act 1981 involves the use of multipliers. The second approach uses prevalence data from representative population based surveys conducted by the Australian Institute of Health and Welfare for the National Drug Strategy Household Surveys. It should be noted that these surveys involve relatively small samples of users and as they have high standard errors produce unreliable estimates. Select Committee Estimate The Interim Report of the Select Committee Into the Misuse of Drugs Act 1981, Taking the profit out of drug trafficking, estimated that there were between 43,200 and 57,600 active heroin users in WA in 1996 (at page 71). This was the basis of the estimate of 50,000 users provided to the estimates committee. The lower end of the range of the estimate of 15,000 is based on the assumption that around 30% of users at any one time are likely to be dependent. National Drug Strategy Household Surveys Commissioned research undertaken by the Australian Institute of Health and Welfare, the 1998 National Drug Strategy Household Survey - WA results, which was published in February 2000, contains an analysis of information from the two most recent NDS Household Surveys, in 1995 and 1998. Based on information provided in the AIHW report it is estimated that in 1995 there were 5,480 persons who had recently used heroin in Western Australia (ie had used in the past year). Based on information provided in the AIHW report, it is estimated that in 1998 there were 21,949 persons who had recently used heroin in Western Australia (ie had used in the past year). (b) The methodology as outlined in the Select Committee Report used a treatment multiplier based on research originally undertaken in 1985 in the United Kingdom by Hartnoll. This assumed that every person who was in the treatment program was heroin dependent and that there was a ratio of six to 10 heroin users not in treatment for every one person in treatment. They also estimated there were two to three non dependent heroin users for every dependent user. The estimates based on the NDS Household Surveys are calculated on the basis of the proportion of the total population of persons aged 14-19, 20-29, 30-39 and 40 years and over who are estimated to have used heroin in the previous year. The denominator population is the estimated standard resident population for June 1995 and June 1998 respectively multiplied by the proportion of the population for each age group who are estimated to have used heroin in the past year.
(b) how is the estimate calculated?

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