NDARC Monograph No. 18 (1994)
INTRODUCTION
Injecting drug use was identified as a risk factor in 9.5% of new diagnoses of HIV infection reported during 1992 in Australia, with the seroprevalence among injecting drug users (IDU) estimated to be between 3-5%.
With the advent of the HIV pandemic, the emphasis of treatment interventions aimed at drug users has shifted from drug use per se to the methods used to administer the drugs. The shift has thus been from the promotion of abstinence as the only goal of intervention and treatment to the promotion of safer use within a harm reduction model. This approach advocates that if a person continues to inject, clean needles should be used every time. Other routes of administration are considered preferable to injecting, as they do not involve the risks of parenteral transmission of HIV and other blood borne diseases (e.g. hepatitis B and C). Transitions to and from injecting have major implications for the spread of these diseases by means of needle sharing.
As a result of this change of emphasis, recent research interest has focused on reasons for the choice of routes of administration employed by drug users. The primary focus of these studies has been on routes of administration for heroin use, with the intention of distinguishing those who inject from those who employ other routes of administration such as chasing and sniffing. The questions posed have included: is injecting the route of administration which all persistent users will employ later in their drug career, or do these two groups represent distinct sub-populations? What are the determinants of change from non-injecting to injecting routes of administration?
Such questions have been most often asked in Britain where large proportions of heroin users in some regions do not inject. For example, 48% of treatment admissions in one recent London study were "chasers" i.e. users who inhale the vapours of heroin heated on foil. The early evidence from these studies appears to indicate that not all heroin users will progress to injecting, and that users may vary in their route of administration over time. Transitions between routes of administration were common, with 45% of subjects having changed to injecting, and 34% having changed from injecting to chasing or snorting heroin. A trend towards routes of administration other than injecting has also been recently reported in the United States. Of particular relevance are the findings that those who primarily use heroin by routes other than injecting have significantly less current and lifetime HIV needle risk behaviour.
In Australia heroin is a drug which is almost exclusively injected. This may be attributable to the prohibitively high cost of the drug in Australia in comparison to countries such as the Netherlands and the U.K., and to the fact that the heroin powder available in Australia is not as amenable to smoking as the brown heroin in Europe, which comes primarily from the Golden Crescent.
In Australia the major illicit drug class that displays the variety of administration routes seen in heroin in Britain and Europe is the amphetamines, the use of which has increased in recent years. The NCADA National Household Survey found that there was an increase in amphetamine use between 1988 and 1991. Amphetamines are particularly popular with younger drug users, with nearly a fifth (17%) of 14-24 year old males reporting having used amphetamines. Experimentation with injection of amphetamines is common. Over half (55%) of a sample of Sydney amphetamine users usually injected the drug. Among those who inject, high levels of needle risk behaviour have been reported. One-third of the injectors within the Hando & Hall sample of Australian amphetamine users reported that they had recently shared a needle.
Amphetamine users are a group of drug users who until recently have received little attention from HIV researchers. Most studies of injection practices among illicit drug users have focused on opioid users. From the standpoint of HIV transmission among drug users, a sound knowledge of the prevalence and determinants of different administration routes among amphetamine users appears essential. Such data would enable interventions to be designed which directly address the primary determinants of the choice of injecting as a route of administration. In terms of harm reduction, if large numbers of people are continuing to use amphetamines, the smaller the proportion of injecting users, the lower the prevalence of risky injecting behaviour and parenteral HIV transmission is likely to be.
The current study aimed to ascertain the factors which predict transitions in routes of administration among amphetamine users. If the factors predicting the change of route of administration can be identified, then the route of choice may be amenable to change. Preliminary work in New York has indicated that heroin users can be persuaded to change to a less risky form of administration. A knowledge of what sustains various routes of administration among Australian amphetamine users may enable the design and application of similar interventions to this population.