Mike McDonough: Opioid consensus

DRUG addiction, like other diseases has a multifactorial aetiology — it is not the result of genetic predisposition or family environment alone, but it does require drug exposure.

The opportunities to acquire a drug of addiction and maintain the supply of that drug are one of the important aetiological factors that determine (and prevent) drug addiction.

During a recent heroin epidemic, increased availability of heroin (making it cheaper) was clearly associated with increased addiction and related harms including a dramatic increase in heroin-related deaths. Conversely, when supply diminished, so too did the heroin epidemic.

Hence, the relationship between drug supply, drug addiction and drug-related harm is a fundamental one.

In the past decade, the rate of pharmaceutical opioid analgesic prescribing has dramatically increased in Australia and increased recognition of opioid-related harm is now evident, as it has been for nearly two decades in North America. It was reported in the US that opioid analgesic-related deaths now exceed the annual motor vehicle mortality rate.

What is most concerning is that opioid prescribing has escalated despite minimal evidence for its use in non-malignant pain, and beyond various clinical guidelines and despite increasing calls for caution with opioids.

Long-term opioid prescribing carries even more significant risks of adverse effects. Recent evidence indicates that patients taking doses of 200 mg morphine-equivalent daily for prolonged periods have an appreciable increased risk for opioid-related death and also that interventions to limit the dose prescribed (eg, ranging between 120 mg–200 mg daily maximum) have been associated with reductions in opioid mortality.

Last year in Melbourne, at a forum on S8 opioid prescribing, it was acknowledged that we have a professional responsibility for action in regards to opioid prescribing, a sentiment shared by physicians elsewhere.

Medical consensus about opioid prescribing practices is likely to be both more reasonable and effective than calls for penalties.

Like most professions, the medical profession is a self-regulating body, and it is preferable to have the profession as a whole establish a consensus about opioid prescribing practices rather than waiting for “others to act”, such as by increasing regulation and/or penalties.

Any prescription drug epidemic, by its nature, requires prescription/prescribing doctor participation, with iatrogenesis recognised as a significant and potentially preventable component of this epidemic.

Currently, it appears that because a lot of doctors are prescribing high doses of opioids and for protracted periods, this practice may have become somewhat normative. Adopting a daily dose threshold of 200 mg morphine-equivalent would seem a reasonable place to start in view of the evidence.

If accepted by consensus, this could send a clear message to the profession that prescribing at this dose or above for prolonged periods is associated with increased mortality risk. That might also promote additional caution by prescribers on any further dose escalation, consideration for specialist review and may even have a public health benefit by discouraging prolonged and high-dose prescribing.

The dosage threshold may also remind prescribers that continuing such treatment carries considerable risk and should prompt a re-evaluation of the risk–benefit ratio. Any continued prescribing should, as always, incorporate a continued focus on the monitoring of both safety and efficacy of any opioid medication.

It is reasonable to assert that the prescription opioid epidemic is largely an iatrogenic problem and is therefore preventable. The structure of our health system may be implicated in the prescription opioid epidemic as prescribers may be unaware that patients they are treating with opioids are attending one or more other doctors for similar prescriptions.

In many states, an opioid permit system operates to discourage multiple opioid prescribers. Currently, in Tasmania, real-time recording of S8 prescription drugs has commenced and eventually may greatly help reduce multiple opioid prescribing.

There have been many calls for action on opioid prescribing consequences and questions raised about physician/prescriber responsibility, but I believe in a profession-wide consensus. In the meantime, we still have the principle primum non nocere.

Associate Professor Mike McDonough is the head the addiction medicine and toxicology unit with Western Health in Melbourne.

Detailed references available on request to editor@mjainsight.com.au

Posted 22 April 2013