Post-hospital prescription opioid use: what do the statistics say?

A new study details the scale of prescription opioid use after a hospital or emergency department (ED) visit, providing insights on how often people then go on to long-term and potentially problematic use of these medicines in NSW.

The study from UNSW’s National Drug & Alcohol Research Centre (NDARC) and the Medicines Intelligence Centre of Research Excellence found the proportion of hospital or ED visits where people started opioids — such as oxycodone, morphine or tramadol — and remained on them long-term was small and declined over the 2014–2020 period.

Long-term use

“Australia has looked on with concern at the widespread harm from prescription opioid painkillers in the US,” said pharmacist and epidemiologist Kendal Chidwick, lead author of the study which was published today in the British Journal of Clinical Pharmacology.

“While these medicines are an important tool for reducing moderate to severe pain in the short-term, they have significant side effects.

“Our analysis suggests that efforts to reduce opioid use in Australia have been successful, in terms of post-hospital use.”

The researchers used confidentialised health data to follow all hospitalisations and ED visits in NSW between 2014 and 2020, focusing on people who had not used prescription opioids in the year before.

Long-term use was defined as 90 or more days continuous opioid use at some time during the period between 90 to 270 days after starting.

The study is the largest of its kind in Australia to date, the authors claim. As the state with the largest population, results for NSW are likely representative of Australia-wide trends.

Measures to reduce use paying off

Until recently, Australia’s use of prescription opioids was increasing, and with it worries about dependence, overdose and death.

“Previous research suggests that about half of all prescription opioids are started after a hospital or ED visit,” said co-author Dr Malcolm Gillies, who is a biostatistician from the Medicines Intelligence Research Program at UNSW. “That can go on to long-term use.”

Over the last few years, Australia has deployed a range of measures to reduce opioid use and related harms. Measures have included smaller pack sizes, restricting repeat dispensings and changing low-dose codeine to prescription-only, alongside real-time prescription monitoring and increasing implementation of opioid stewardship programs in hospitals.

“It appears that the tide has changed in Australia, with reductions in opioid use after hospital admissions,” Gillies said.

“Our study revealed that both starting an opioid after a hospital or ED visit, and remaining on it long-term, declined over time, which is good news.”

From 2014 to 2020, overall opioid initiations decreased by 16%, from 8.7% to 7.2% of hospital/ED admissions, and long-term opioid use decreased by 33%, from 1.3% to 0.8%.

“Ensuring that each patient has their pain effectively managed while minimising harms is key when it comes to opioid prescribing,” Gillies said.

“Looking at the bigger picture, best-practice care of chronic pain will mean increasing access to coordinated multidisciplinary pain services.”

Patient demographic and admission characteristics

The study also found that one in four people admitted for trauma, such as a physical injury or road accident, started an opioid and 2.3% of them went on to long-term use. Traumatic injuries can result in chronic pain in some patients, which might lead to long-term opioid use. This rate of long-term use is somewhat lower than reported in previous Australian research.

One in 15 people attending ED started an opioid and 1.0% of them went on to long-term use. This is lower than estimates from the US.

“It’s reassuring to have evidence, at the population level, that Australia’s rates of long-term prescription opioid use following hospital and ED visits are low compared to some other countries,” Chidwick said.

“Our results highlight variation by patient demographic and admission characteristics.

“Continued opioid stewardship is critical to ensuring the balance of benefits and harms.”

Long-term use of opioids was low after Caesarean sections and planned surgeries such as hip replacements or tonsillectomies, despite high rates of starting an opioid among these groups, mostly for managing post-operative pain.

One in five obstetric admissions involving surgery and one in 10 planned surgical admissions resulted in an opioid dispensing; however, less than 1.0% of these progressed to long-term use.

The importance of linking data

In 2022, Australia released its first national clinical care standard on Analgesic Stewardship in Acute Pain. Before this, individual stewardship programs varied across hospitals.

“Insights from such large studies like ours will inform stewardship programs and promote quality prescribing practices,” said co-author Professor Sallie Pearson, pharmacoepidemiologist at the School of Population Health at UNSW.

“Linking health data across systems enables large sample sizes over long time frames and reveals the ‘real world’ use of medicines in Australia,” Pearson said.

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