Who is using oxycodone in NSW and why?

A sociodemographic study of oxycodone usage in NSW shows women of childbearing age, people living in regional areas and older people were more likely to have been prescribed the opioid.

A demographic study of the use of oxycodone in NSW has found the likelihood of first-time use increased with age and was more commonly used by people living outside major cities.

Oxycodone (also known as brand names including OxyContin and Endone) is a strong opioid medicine that is commonly prescribed around the world to manage cancer as well as acute and chronic pain.

In recent decades, its use has been subject to much scrutiny due to a prescription opioid addiction epidemic in America. Despite this attention, little is known about why, and in which settings, opioids are prescribed in Australia.

Harmful use of prescription opioids can result in addiction, overdose and even death. To understand the associations between opioid use and sociodemographic factors, researchers from the Medicines Intelligence Research Program and National Drug and Alcohol Research Centre (NDARC) at UNSW Sydney looked at linked data involving more than 800,000 people prescribed the opioid in the years 2014 to 2018.

The study, which was published recently in the British Journal of Clinical Pharmacology, found that the likelihood of first-time oxycodone use increased with age and was more commonly used by people living outside major cities. About half of new oxycodone use in NSW was after a recent episode of hospital care or a procedure, while the other half was initiated by general practitioners or specialists for other reasons.

“Many people are concerned about using oxycodone given that it is a strong opioid,” says study lead author Dr Malcolm Gillies, who is a biostatistician from the Medicines Intelligence Research Program at UNSW.

“Our study shows how linked health data can generate insights into how opioids are used in the Australian community. This knowledge helps inform interventions that will improve prescribing practice and quality use of medicines.”

Pathways to oxycodone prescriptions

The study used linked data from NDARC’s POPPY II study, a retrospective cohort of NSW residents who initiated a prescription opioid through the Pharmaceutical Benefits Scheme. To assess oxycodone use, the researchers examined linked data on PBS medicines dispensed, Medicare claims, hospitalisations and emergency department (ED) visits for the period between 2014 and 2018, covering roughly 800,000 people.

The study found that during this period, 30 per cent of people starting a new course of opioids were prescribed oxycodone rather than another opioid. Annually, 3 per cent of people in NSW used oxycodone for the first time, while about the same proportion of the population had ongoing prescriptions for oxycodone.

The most common reasons to be prescribed oxycodone were discharge from hospital, having a recent therapeutic procedure, or after a visit to ED.

“Acute care and procedures like joint or hip replacement surgery, caesarean section and other surgeries accounted for about one half of all new oxycodone use,” says Dr Gillies.

“On the other hand, hospital admission for injury or a past-year history of cancer were less common reasons for oxycodone initiation.”

Persistent use of oxycodone

Two-thirds of the time, people used a single pack of oxycodone and then stopped. However, 4.6 per cent of people were still using oxycodone a year after initiation.

“This provides an estimate of long-term or persistent use; however, this number does not consider the use of other opioids such as codeine,” says Dr Gillies.

“Even after a serious operation we would expect the need for oxycodone to relieve pain would be over by 90 days.

“The fact that a proportion of people were taking oxycodone 12 months later underlines the need for early, careful assessment of ongoing pain to maximise appropriate use of non-opioid and non-pharmacological pain control.”

New Australian hospital care standards require that hospital prescribers prepare an opioid weaning and cessation plan, to be started as soon as clinically appropriate, and provide it to the patient’s general practitioner on discharge.

“While our study describes if and when oxycodone was used, it can’t shed light directly on the proportion of use that was inappropriate,” says Dr Gillies.

Only about 1 per cent of those prescribed oxycodone in NSW between 2014-2018 had a history of opioid dependence.

Sex, age and postcode of oxycodone use

New oxycodone use in women aged 18–44 years (i.e. of childbearing age) was significantly higher than for men of equal age, highlighting the contribution of opioid initiation after delivery by caesarean section.

Oxycodone use among people living in areas outside the major cities was significantly elevated. However, this higher rate of new use in rural and regional areas could not be explained by age, sex nor socioeconomic disadvantage alone.

“Our findings are consistent with other Australian findings of increased opioid use outside major cities but differ in finding no socioeconomic gradient,’ says Dr Gillies.

Further explanation will require data on service accessibility as well as detailed, population-level data on acute and chronic pain conditions.

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