Increase in opioid use in New Zealand 'should spark concern', University of Auckland researchers warn

Researchers are concerned about increasing rates of opioids being given to older patients in New Zealand.

Opioids, a class of pain medication, have the potential of 'epidemic' level addiction as seen in the US, they warned. The US epidemic has led to a surge in illegal sales, overdoses and deaths.

"Opioids are commonly prescribed for pain and, while we don't yet have an epidemic in New Zealand as in the US, these findings should spark concern," the University of Auckland's School of Pharmacy Associate Professor Amy Chan said.

The warning comes after researchers at the university looked at two studies on opioid use in New Zealand.

One study looked at persistent use among 260,000 opioid-naïve patients who underwent surgery between 2007 and 2019 and were dispensed opioids after discharge.

They found the overall rate of persistent use - meaning used beyond 90 days after an event - was over 9 percent.

"Risk factors for persistent use included prescriptions of higher opioid doses, multiple types of opioids and changing to different opioids in the first 90 days after discharge," pharmacy lecturer and lead author Jiayi Gong said.

Meanwhile, the second study looked at the upward trend of use specifically in older people.

The study looked at more than 800,000 people over 65 years old, from 2007 to 2018, and found steadily increasing opioid prescribing.

The increase was especially among women and those over 85 years of age.

Hoda Fahmy, who led this research, said this was problematic.

"Opioid therapy should only be considered when potential benefits are likely to surpass risks, where it should be prescribed with extensive monitoring and regular assessments to determine the need for continuation," she said.

"Future research is warranted to discern whether the increase in opioid dispensing is a consequence of overprescribing or reflects appropriate pain management practices and to establish evidence-based guidelines for the use of opioids in the older population."

Researchers found codeine was the most commonly prescribed opioid, followed by tramadol. Other opioids include dihydrocodeine, and stronger forms, fentanyl, morphine, pethidine and oxycodone.

At the time of the study, codeine was allowed to be prescribed for three months' supply. But from October 2023, codeine supply was limited to one month.

Fentanyl showed the greatest increase over the study period, which Fahmy said was probably due to the fact funding for fentanyl patches became unrestricted in February 2011.

The findings comes as a US government-backed briefing highlighted New Zealand as a country with a high risk emerging of fentanyl abuse.

Fahmy believes increasing prescription of opioids in older adults should continue to be monitored and inform policies and prescribing.

Co-author Chan added that while both codeine and tramadol are weak opioids, they are still a cause for concern, especially in older patients.

"Weak opioids can still lead to dependency and carry additional risks for older people who are more susceptible to side effects, as their kidney function is often reduced and it is important for processing these medicines," she said.

Chan suggested that patients and their families should keep an eye on opioid use and seek a medication review for long-term use. 

She also called for cautious prescribing and policy vigilance regarding opioid supply.

Further research out of the School of Pharmacy will look at opioid prescription in rest homes and the social and economic impacts of opioid use, especially as more up-to-date data become available.