Proof opiates are useful for chronic back pain 'lacking'

"Powerful painkillers doled out in their millions are ineffective against back pain," the Daily Mail reports.

An Australian review found evidence for the effectiveness of opiate-based painkillers, such as tramadol and oxycodone, for chronic back pain was "lacking".

The review pooled the findings of 20 trials investigating the safety and effects of opioid painkillers for non-specific or mechanical chronic lower back pain.

This is back pain with no identified cause, such as a "slipped" disc or injury. This is a common, yet poorly understood, type of back pain that is often challenging to treat.

The trials found opioids had a minimal effect on pain compared with an inactive placebo – about half the level that would be needed for a clinically meaningful effect.

The rate of intolerance was also very high, with often half or more people experiencing side effects like nausea and constipation, and withdrawing from treatment as a result.

The findings lend support to national guidelines for the management of non-specific lower back pain, which suggest it is inadvisable for a person to rely solely on painkillers.

Self-management techniques, such as education, exercise programmes, manual therapy and sometimes psychological interventions, may deliver greater lasting benefits.

If pain relief is needed, weaker painkillers, such as paracetamol, and anti-inflammatory drugs, such as ibuprofen, are advised initially, with strong opioids only used for a short period of time for severe pain.  

If you are having trouble coping with chronic pain, contact your GP, who may be able to recommend additional treatments and services.

The study was carried out by researchers from the George Institute for Global Health at the University of Sydney, and other institutions in Australia.

Funding was provided by the Australian National Health and Medical Research Council.

The review was published in the peer-reviewed journal JAMA Internal Medicine on an open-access basis, so it is free for you to read online.

The Mail's reporting of the study was generally accurate, but the headline in the print version of its story – "Back pain drugs 'do more harm than good'" – is unsupported.

The study only considered short-term side effects such as nausea and constipation, and not the longer-term problems addressed in the paper's reporting, like addiction and overdose.

This systematic review and meta-analysis pooled the results of randomised controlled trials, aiming to see whether opioid painkillers such as codeine, tramadol and morphine are safe and effective for managing lower back pain.

Although people with chronic lower back pain may often resort to the use of opioids because lesser painkillers are ineffective, the researchers say there has been no systematic study examining their effects and tolerability at different doses.

A systematic review is the best way of gathering the available evidence to look at safety and effectiveness, but the strength of a review's findings are only as good as the studies it includes.

The researchers searched several literature databases to identify randomised controlled trials of opioid use in people with non-specific lower back pain.

Sometimes called mechanical lower back pain, this is back pain where no specific cause can be identified, such as a herniated, or "slipped", disc, inflammatory conditions, infection, or cancer, for example.

Trials were eligible if they compared an opioid with inactive placebo, or compared two different drugs or doses, and reported outcomes of pain, disability or adverse effects.

There were no restrictions on the duration of back pain, painkiller use, use of other medications, or the presence of other illnesses. Two researchers reviewed and quality assessed studies, and extracted data.

The trials included rated pain on visual or numerical scales (for example, rating pain from 0 to 100) and disability scores on questionnaires such as the Roland Morris Disability Questionnaire and Oswestry Disability Index.

The researchers reported the mean difference in scores between the opioid and control groups. A difference of 10 points on a 100-point scale was a minimal difference required for any effect on pain, but a 20-point difference was considered a clinically meaningful effect.

The researchers were mainly interested in short-term effects on pain relief. They also looked at the number of people who withdrew from the trial or were lost to follow-up as a result of adverse effects or lack of effect.    

Twenty trials involving 7,295 people were identified, 17 of which compared opioids with placebo, while two compared opioids with each other.

All the trials examined effects in the short term only – the maximum treatment and follow-up period was three months. The trials were generally high quality. 

The pooled results of 13 studies (3,419 people) found opioids had a minimal effect on pain – there was a mean 10.1 score difference between opioids and placebo (95% confidence interval [CI] 7.4 to 12.8 reduction).

The difference when using single-ingredient opioids was 8.1, and 11.9 when using an opioid combined with another simple painkiller, like paracetamol.    

There was limited data available for disability. Two studies found the combination of tramadol and paracetamol had no effect on disability compared with placebo, while another found no effect for morphine. However, the quality of evidence for these outcomes was said to be very low.

The researchers looked at studies with a run-in period separately. This is where only those who responded favourably during the trial phase were actually randomised. Such trials therefore preferentially only include good responders.

These results found increasing opioid dose was associated with better pain relief, but clinically meaningful effects on pain were still not seen at any of the doses evaluated.

When looking at the two head-to-head trials directly comparing two opioids/doses, both trials found around a five-point score difference.

The proportion of participants who withdrew was high in all trials – up to around 50% or greater withdrew.

The main cause for withdrawal was lack of effect or adverse effects. More than half the people taking opioids experienced side effects such as nausea, constipation and headaches. 

The researchers concluded: "For people with chronic low back pain who tolerate the medicine, opioid analgesics provide modest short-term pain relief, but the effect is not likely to be clinically important within guideline recommended doses." 

This systematic review found no evidence that opioids provide a meaningful effect on chronic non-specific lower back pain.

Opioids are often used as a last resort for people who have not responded to other painkillers. But these results found opioids gave only half the size of the effect that would be needed to make a real difference – about a 10-point score difference, rather than 20.

On the whole, the body of evidence was high quality. A large number of trials where identified, and most were multi-centre trials with good sample sizes carried out in the US, Canada, Australia and Europe. This means the findings should be representative of people with this condition in the UK.

Most of the evidence compared the effect of opioids with placebo only, rather than any other active intervention.

And 17 of the studies were funded by the pharmaceutical industry, giving uncertain potential for publication bias.

However, in these cases, if anything, you would expect to see an overly favourable effect of opioids, which is not the case.  

The extremely high dropout rate also cannot go unnoticed – 50% or greater in many studies.

This may have contributed to the lack of effect seen, but also demonstrates the difficulty there is tolerating these strong painkillers. Many people experience debilitating side effects when taking them, such as nausea, vomiting and constipation.  

Chronic non-specific lower back pain is an extremely common cause of disability in the UK. Perhaps overreliance on pain killers and anti-inflammatory drugs isn't the best answer.

As the guideline body the National Institute for Health and Care Excellence (NICE) says, a key focus should be on helping people manage their condition themselves through education and information, exercise programmes, or manual therapy.

Chronic non-specific pain can sometimes also have a psychological element, and interventions such as cognitive behavioural therapy can be helpful.

NICE recommends regular paracetamol as the first-choice option for pain relief. If this is insufficient, they suggest moving to non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, or weak opioids, such as codeine, but being aware of the potential side effects of both.

Stronger opioids, such as fentanyl or oxycodone, are only advised for short-term use for severe pain.     

These recommendations, and the findings of this review, do not apply to people with identified causes of their back pain, such as inflammatory conditions, infections, cancer, or trauma. 

If you have been taking opiate-based painkillers for some time and feel you no longer need or want to take them, you should talk to your GP. Stopping suddenly is not a good idea as this could trigger withdrawal symptoms.

For more information, visit the NHS Choices guide to back pain.