Simon Holliday: A chronic pain tightrope

PRESCRIPTION opioid analgesics are an essential part of the management of acute and terminal pain.

However, with the growing use of opioids for chronic non-cancer pain such as acute low back pain — usually recurrent and often prolonged — we are seeing increasing rates of harmful use or diversion.

GPs often have to deal with the maintenance of an opioid regimen for acute cancer pain with little training, so may uncomfortably walk the tightrope of neither wishing to under-treat pain nor wishing to foster harms such as addiction. Now, with 20% of GP consultations involving chronic pain but few GPs receiving specific training, it becomes a frequent dilemma.

Several promising alternatives for chronic non-cancer pain such as fish oils, pregabalin and duloxetine currently lack Pharmaceutical Benefits Scheme subsidies, so the natural response to chronic pain is to re-prescribe subsidised opioids.

Opioids do reduce pain levels in the immediate post-dose period but significant improvement in levels of pain and function occur in less than 26% of long-term users.

In population epidemiological studies, opioids do not improve any of the key outcome treatment goals — pain relief, improved quality of life or improved functional capacity.

Almost half the patients who start opioids for chronic non-cancer pain stop them due to the classical side effects but many doctors and patients are unaware of the minefield of newly described toxicities. These include an exaggerated response to both physical and emotional pain, which seems to particularly be found in patients with past or present psychiatric or substance use problems.

Opioid-induced changes in “affective tone” leave patients without the usual emotional resources to cope with the pain and opioid toxicities. Opioids have been associated with endocrinopathies, suicides, inadvertent overdoses and sleep apnoea.

A major problem is the issue of hoarding or diversion, with 60% of those on opioids hoarding them. Among university students given opioids for acute pain, 27% reported diverting them. Some (18%) of those abusing opioids obtained them from just one doctor.

However, the majority of opioid abusers obtain their stock not from dealers but from family or friends. These are given freely (56%), purchased (9%) or stolen (5%). The person providing the opioids usually (82%) obtained them from just one doctor.

The widespread adoption of opioids in chronic non-cancer pain has been underpinned by pharmaceutical company research, marketing, funding of professional and consumer organisations and of professional education. From a low base rate, by 1999 86% of the opioid market was for chronic non-cancer pain treatment. The author more recently observed frequent prompting for opioids from nurse practitioners and from pharmacists conducting medication reviews, with both groups looking for a simple solution to an identified problem.

We are recruiting a population very different to that used in the trials of these drugs. In a prospective US study from 2001-2005, half of all past opioid abusers became long-term prescription opioid users.

The consequence of the experiment of extending prescription opioids to those with non-cancer pain is that now 29% of entrants to opioid substitution therapy units report their primary opioids are those introduced to them by doctors for pain management.

Most GPs have very strong aversions to opioid addicts or being associated with them professionally. This binary approach obscures the non-judgemental systematic approach of universal precautions.

GPs need proper support and resources so that initial screening, preventive monitoring, minimisation of hoarding and diversion, and advice about the safe disposal of unused opioids becomes a universal feature of the treatment of chronic non-cancer pain.

Dr Simon Holliday is a GP in Taree, NSW, specialising in addiction medicine.

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

Posted 31 October 2011

[poll id="134"]