Long-term opioid prescribing increasing despite questionable efficacy

Opioid prescribing in England increased from 2010 to 2014 despite these drugs increasingly being considered ineffective in the treatment of chronic non-cancer pain, a study published in the British Journal of General Practice has shown.

There is growing controversy about the long-term use of opioids in treating non-cancer pain. | iSTOCK
There is growing controversy about the long-term use of opioids in treating non-cancer pain. | iSTOCK

Researchers analysing opioid prescription data from August 2010 to February 2014 found there was an increase in the total amount of opioid prescribed in primary care in England, in equivalent milligrams of morphine (Spearman's correlation co-efficient [r]=0.48).

Prescribing increased for buprenorphine, codeine, morphine, oxycodone and tramadol, with buprenorphine and codeine showing the greatest rate of increase over the study period. Tramadol was the most prescribed opioid in England.

Prescribing decreased for methadone and dihydrocodeine over the study period. Fentanyl was, by far, the least prescribed drug and the quantities prescribed remained fairly constant over the study period.

The authors posit several reasons for the increase in tramadol prescribing: the withdrawal of co-proxamol in the 2000s; a preference for tramadol over NSAIDs because of concerns over complications (especially in older people); and a perception that the drug lies between weak and strong opioids, providing a false sense of security to prescribers hoping to avoid the stigma and risks of 'strong' opioids.

The decrease in methadone prescribing may be related to the rise in prescribing of burprenorphine, which is an alternative treatment for opioid dependence.

Lesser-prescribed opioids, such as diamorphine, pethidine, and the recently licensed tapentadol, were not included in the study.

Social deprivation

In addition, the study revealed regional variations in prescribing, raising questions of inequality of care. The data showed a north-south gradient in opioid usage, with 9 out of 10 of the highest prescribing areas located in the north of the country (r=0.66, p<0.0001). There was also an association between social deprivation and higher opioid prescribing (r=0.56, p<0.0001). 

Chronic pain is known to disproportionately affect patients of lower socioeconomic status and a lack of services in deprived areas may also contribute to inappropriate opioid prescribing.

Although the study could not differentiate prescriptions for chronic pain from those for end-of-life pain, a 2014 study found that only 12.2% of the prescriptions for strong opioids in England are written for cancer pain.

In conclusion, the authors report that 'Long-term opioid prescribing is increasing despite poor efficacy for non-cancer pain, potential harm, and incompatibility with best practice'.

They suggest that with greater adherence to evidence-based treatment guidelines for chronic pain from the British Pain Society and Map of Medicine 'opioid prescription would be likely to fall and the function of those with chronic pain [would] improve'.

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