Codeine use and harms in Australia: evaluating the effects of re-scheduling

Globally, codeine is the most-used opioid. In December 2016, Australia announced that low-strength codeine (≤ 15 mg) would be re-scheduled and no longer available for purchase over-the-counter; this was implemented in February 2018. We aimed to evaluate the effect of this scheduling change on codeine misuse and use and misuse of other opioids.

Interrupted time-series analysis of monthly opioid exposure calls to New South Wales Poisons Information Centre (NSWPIC, captures 50% of Australia's poisoning calls), January 2015- January 2019 and monthly national codeine sales, March 2015-March 2019. We incorporated a washout period (January 2017 - January 2018) between the announcement and implementation, when prescriber/consumer behaviour may have been influenced.

Intentional opioid overdoses resulting in a call to NSWPIC.

We used linear segmented regression to identify abrupt changes in level and slope of fitted lines. Codeine poisonings and sales were stratified into high strength (> 15 mg per dose unit) and low strength (≤ 15 mg). Only low-strength formulations were re-scheduled.

We observed an abrupt -50.8 percentage [95% confidence interval (CI) = -79.0 to -22.6%] level change in monthly codeine-related poisonings and no change in slope in the 12 months after February 2018. There was no increase in calls to the NSWPIC for high-strength products, level change: -37.2% (95% CI = -82.3 to 8%) or non-codeine opioids, level change: -4.4% (95% CI = -33.3 to 24.4%). Overall, the re-scheduling resulted in a level change in opioid calls of -35.8% calls/month (95% CI = -51.2 to -20.4%). Low-strength codeine sales decreased by 87.3% (95% CI = -88.5 to -85.9%), with no increase in high-strength codeine sales in the 14 months following re-scheduling, -4.0% (95% CI = -19.6 to 14.6%).

Codeine re-scheduling in Australia appears to have reduced codeine misuse and sales.