MAPPING THE CONSEQUENCES OF AN UNANTICIPATED DRUG SUPPLY CHANGE OF UNCERTAIN ORIGINS: RESPONSE TO THE COMMENTARIES

Events such as the Australian heroin shortage are rare. They have been even less often studied systematically using the rich array of data available in the Australian case. The interpretation of ecological data is fraught with difficulties, so we welcome the insightful commentaries on our paper [1]. Our responses to them are divided into two broad categories: comments on the consequences of the heroin shortage and our interpretation of them; and the policy implications to be drawn from the shortage. We agree that the huge drop in fatal and non-fatal overdoses was the most striking consequence of the Australian heroin shortage. Gossop [2] queried two of our interpretations: first, could we be sure, he asked, that a reduction in numbers of syringes dispensed by needle and syringe programmes meant that injecting drug use had declined? His substantive point is that frequency of injection may have changed; this could have been the case for VIC, but was less clear for NSW. Our interpretation was based upon two key findings: the sustained reduction in numbers of syringes distributed in NSW after a decade long increase in numbers, and a drop in HCV notifications among young people [3], which suggests that there was not a huge increase in numbers engaging in stimulant injecting. Moreover, the interpretation of these data was supported by key experts and other data derived from those working with the population, who reported reductions in the number of young people presenting to services [3, 4]. Secondly, can we be sure that the heroin shortage has produced a ‘net gain’? We believe so for the study period to date. The main reason is the very large reductions in heroin-related mortality (of the order of 300–400 fewer deaths) and morbidity and either no increase or a small reduction in property crime. The reduction in mortality alone is a very large gain in life years among young adults, and it was not obviously outweighed during the period of study by any offsetting increases in problems related to methamphetamine and cocaine use, which increased only very modestly. We agree with Weatherburn that the net positive consequences of the shortage to date may not have occurred if other circumstances had not been so propitious, including reductions in cocaine availability (after the increases initially seen in NSW [5, 6]), increased treatment access (and other forms of demand and harm reduction that are well-established in Australia), and increased male employment. Jaffe [7] comments on the fact that there did not appear to be a switch from smoking or snorting of heroin to injection as a consequence of the reduction in quality and increase in price of the drug. It is important to note that most heroin users in Australia were already using injection as a route of administration; his concern—that such a supply change in countries where intranasal or smoking as routes of administration were common—might be an issue of concern, and it reinforces our belief that harm and demand reduction efforts (discussed below) are critically important alongside supply side interventions, to attempt to reduce the harm resulting from any such shifts. The very modest effects on crime might be considered puzzling, given the long-standing assumption (supported by reasonable evidence and a moderate aetiological fraction) that some proportion of property crime in Australia is heroin-related. Reuter [8] and Caulkins [9] were less puzzled, suggesting that modest effects should be expected because of the shift in drug purchases to others drugs and an inelasticity of demand for heroin and other drugs among more dependent heroin users who were less likely to cease heroin use and more likely to switch to methamphetamine. Caulkins [9] also argues that more economically informed structural modelling analyses of the time-series would not have tested for the effects that we did. We agree that more economically informed modelling is desirable. The time-series analyses of the effect of the heroin shortage were developed on the fundamental assumption that we have limited knowledge about heroin price, availability and purity measures that could be used to assess direct effects of the shortage on heroin markets. We therefore examined indicators of heroin-related harms, in order to describe the major effects of an abrupt change in a heroin market and how these would be manifested across the different jurisdictions under study. We feel that economists should consider using the results of this data-based modelling strategy to infer new information about drug markets, which they can perhaps then test with innovative research methods on the available indicator data. Time-series modelling was largely to decide which changes could not be attributed to chance. The comments of Mann [10] were interesting in that he felt that they corresponded to predictable, previously documented phenomena in the alcohol field. We would welcome the collaboration of experts in more detailed and economically informed analyses of the time-series data that we have collected. Several commentators have essentially asked the question as to whether the Australian heroin shortage represents a victory for supply side drug policies [11-13]? The rush by some to proclaim the Australian heroin shortage as a ‘victory’ for supply control policy has been answered by an equally swift and reflexive rejection of this possibility by some proponents of demand and harm reduction policies. Both responses are understandable. The supply-side of the drug policy debate has not had many unequivocal wins; and sceptics of supply side efforts often point to studies in Australia, Canada, the United Kingdom and the United States that have failed to detect any impact of drug seizures on drug price and other indicators of drug use [14, 15]. Mark Tyndall's commentary [12] represents one example of understandable concern that our work is not taken to represent a view that aggressive supply-side interventions should be the sole or major focus of drug policy, a view that we strongly support. Unfortunately, the polarization of opinion about the causes and policy lessons of the Australian heroin shortage has hampered the task of describing and understanding the event and its most immediate consequences. Before extracting policy implications from the event, we considered it important to carefully document its effects. We did not discuss the causes of the shortage in this paper for the reasons just given. Several of the authors have done so in detail elsewhere, where they came to the conclusion (largely on the basis of the implausibility of any of the alternative explanations) that supply reduction efforts by law enforcement, targeted at high level internationally run trafficking syndicates, contributed in part to the shortage [16], the effects of which were mediated by steep increases in the price of heroin, as indicated by Reuter [8]. We feel that it was the successful disruption of high level trafficking syndicates, rather than the scale of seizures per se, that was important in this instance [16]. The longer-term effects of the shortage may not prove to be as positive as they have been in the short term. We agree with Caulkins [9] and Gossop [2] that these changes are likely to prove transitory in the longer term and that the public health and order effects of the shift to methamphetamine injecting may prove very unwelcome. Some front-line police and health staff are already comparing the effects of methamphetamine use on injectors unfavourably with the effects of heroin use. There are also strong reasons to doubt the reproducibility of the Australian experience in other similar countries, whatever we take its causes to be. As Weatherburn [13] points out, the application of Australia's experience is limited given Australia's geography, the small size of its population and drug market in international terms, and its distance from the major source countries. Further, the differences in the way in which the shortage was manifested across the different jurisdictions suggests that local conditions will also affect outcomes. It may not even be possible to apply lessons from heroin to methamphetamine in Australia because methamphetamine is, in large part, domestically produced, which presents a very different set of problems for law enforcement and health. Finally, we think it important to remember that Australia has a history of timely and innovative implementation of novel harm reduction measures, and good implementation of demand reduction measures that (in this case) importantly include steadily increasing treatment places for opioid pharmacotherapy and widespread needle and syringe programmes. Without such established programmes, reductions in heroin supply may have had dramatically different (and negative) outcomes. Rather than signalling a ‘win’ for supply reduction, we argue that the results of this study [6, 17-19] suggest that a modicum of success in one facet of drug policy may be better achieved in the context of established success in the others.

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