[Commentary] FUTURE CHALLENGES FOR HEROIN AND OTHER OPIOID SUBSTITUTION TREATMENT

Verthein and colleagues report a 2-year follow-up of heroin-treated patients enrolled in the German heroin trial [1]. The key findings of this paper are that (i) the immediate benefits in health, drug use and criminal activity seen in the first 12 months of heroin-assisted treatment (HAT) are maintained over 2 years, and (ii) that social benefits (e.g. work, housing) continue to improve the longer-term patients’ stay in treatment, indicating that, as expected, these changes take longer to achieve. As such, social improvements are often the key determinants of longer-term abstinence [2] and the study reinforces the importance of long-term treatment, as well as providing further evidence of the safety and effectiveness of HAT beyond 12-month randomized controlled trial (RCT) data. Retention in HAT in the second year was quite high, with 82% of patients at 1 year being retained at 2 years. Of concern, however, is that HAT was less effective in retaining individuals with higher levels of polydrug use (cocaine, benzodiazepines), unstable housing and those with greater criminal activity. One of the key stated rationales for HAT is to attract and retain such individuals who are not well served by conventional methadone maintenance (MMT). A re-analysis of the German data focusing on these complex patients would be interesting to determine whether there are indeed substantial benefits of HAT over MMT for this ‘difficult-to treat’ group. Although the study reports statistically significant differences in end-points of global health (80% versus 74%) and self-reported illicit drug use (69% versus 55%), the effect sizes are modest—with numbers needed to treat (1/absolute risk reduction) of 17 and seven patients, respectively—that is, 17 and seven patients need to be treated with HAT in order to make significant improvements in one patient on these outcomes. Given the recent relatively positive findings of various RCTs of HAT [3–5], the key question for HAT is how it can be extended beyond ‘investigational’ status to become an accessible treatment modality available as part of the spectrum of clinical services available to heroin users. Inevitably, the expansion of HAT faces greater political and community challenges than other forms of opioid substitution treatment, with some critics discounting HAT as treatment per se (e.g. [6]), criticisms which continue to linger with methadone despite the comprehensive and sustained demonstration of its effectiveness and, importantly, its capacity for rapid, inexpensive expansion. There are two broad areas from a public health perspective that need to be considered for this transition to occur: (i) ongoing concerns regarding HAT efficacy and cost effectiveness and (ii) the capacity for the expansion of HAT that addresses treatment accessibility and maintains safety for individuals and the broader community. While the available RCT evidence for HAT has demonstrated improvements in self-reported outcomes (heroin use, health status, social functioning, criminal activity), critics of HAT will continue to demand objective evidence of efficacy—which for any treatment for heroin use must include objective evidence of reduced illicit heroin use. Two RCTs currently under way—the North American Opiate Medication Initiative (NAOMI) study in Canada and the Randomized Injecting Opioid Treatment Trial (RIOTT) in the United Kingdom [7] include mechanisms for estimating objectively illicit heroin use, and we must await their findings. Furthermore, proponents of HAT must demonstrate its considerably greater expense results in health sector savings compared to investing equivalent resources in expanding MMT and other forms of treatment. We should not assume naively that the health sector will want to pay for an expensive treatment whose principle cost savings may be for the criminal justice system. The extent to which heroin treatment can be expanded must consider ways of making HAT: (i) less expensive; (ii) more accessible to patients, for whom attendance at a clinic two or three times a day interferes with community reintegration or makes treatment geographically inaccessible for many; and (iii) maintain safety for individuals and the community. The first two points could be achieved by allowing take-away doses of heroin (as occurs traditionally in Britain). However, this raises concerns regarding safety, given the continued high levels of life-threatening adverse events (respiratory depression, seizures) reported by Verthein and colleagues; and concerns about risks of medication diversion, which in turn erodes practitioner and community support [8]. It may be that alternative longer-acting injectable opioids (e.g. methadone or buprenorphine) or alternative administration routes (e.g. intranasal, implants) may need to be considered that do not require onerous attendance requirements, and can be delivered less expensively in community settings. We should embark upon the next set of research questions—not simply whether HAT is effective compared to MMT for a small minority of eligible patients, but rather how we can optimize the delivery of different forms of opioid substitution treatment, expanding the variety of opioids and routes of administration beyond currently available treatments, in order to attract, retain and treat effectively more opioid-dependent individuals. This is a more pressing public health priority given the marked expansion in prescription opioid (not only heroin) use and the relative decline in injecting in many countries. No doubt HAT will have a role to play; however, it is unlikely that HAT, delivered in its current constraints, will ever be an option for more than a small minority of opioid-dependent individuals.

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