Opioid prescribing doubled between 1991-2015, with demand most common for chronic non-cancer pain conditions such as lower back pain, according to an international study led by  University of Sydney researchers.

It also found that stronger opioids are more frequently prescribed than weaker opioids for people with chronic non-cancer  pain.

The systematic review of studies from across the world is the first to examine the literature about the extent opioid analgesics are being prescribed to manage people with chronic pain conditions, according to Dr Stephanie Mathieson from the University of Sydney’s Institute for Musculoskeletal Health.

The review evaluated 42 published studies that included 5,059,098 people with chronic pain conditions (other than cancer) from eight countries.

Key findings were:

• Opioid prescribing rates increased from about 20% of people with chronic non-cancer pain to around 40% between 1991 and 2015.
• On average almost one in three patients (30.7%) were prescribed an opioid during this period.
• For patients with chronic lower back pain, 42% were prescribed an opioid.
• The average age of those prescribed an opioid medicine was 55.7 years.
• One in four (24%) of opioids were strong combination products containing opioids (eg oxycodone plus paracetamol).
• Strong opioids (eg oxycodone, morphine, fentanyl) accounted for 18.4% of chronic non-cancer pain opioids
• 8.5% were weak opioids (eg codeine, tramadol).
• 11% were weak combination products containing opioids (eg codeine plus paracetamol).

However Dr Mathieson cautioned that two thirds of studies in the review were from the US and there was an evidence gap for opioid use in non-cancer pain in other countries.

“One of our goals was to establish a baseline of how commonly opioids are prescribed for chronic non-cancer pain which may help determine the success of future opioid mitigation strategies. While we have sufficient data for this purpose for the USA, we have sparse or no data for other countries,” the authors wrote.

There was also insufficient data on the dose and duration of opioids prescribed to patients with chronic non-cancer pain, especially lower back pain, the authors said.

They pointed to guidelines such as those from the Centres of Disease Control and Prevention in the United States that  discourage the use of opioids to manage chronic non-cancer pain. Measures are now being taken to manage the ‘opioid crisis’  – such as Australia’s up-scheduling of codeine – but the authors said  research on opioid mitigation strategies specific to the needs of patients with chronic non-cancer pain is still needed

“The ‘deprescribing’ of opioids needs to address reducing the initial prescription of opioids, but also how to support the cessation of opioids while still providing access to appropriate pain management,” they wrote in the Journal of Internal Medicine.