A prospective cohort study evaluating the impact of upscheduling codeine in Australia among frequent users of codeine

To evaluate and document the impacts of re-scheduling codeine to a prescription-only medication in Australia in February 2018.

Prospective cohort study. Participants completed an on-line survey with a range of outcome measures at four time-points, once before codeine was re-scheduled (November 2017) and three times after the event: 1 month after (February 2018), 4 months after (June 2018) and 12 months after (February 2019).

Australia.

Participants were 260 Australians aged 18 years and above who reported regular over-the-counter (OTC) codeine use and, at the time of the study, were not engaged in treatment for codeine dependence.

Survey measures included estimates of daily average codeine use (mg) and overall daily average opioid use [calculated using an oral morphine equivalent daily dose (OMEDD, mg)], opioid use disorder with regard to codeine use (using a modified Alcohol Use Disorder and Associated Disabilities Interview Schedule-IV), pain and pain self-efficacy, anxiety and depression and health service use.

A reduction in total daily codeine use (mg) from 64.3 mg [95% confidence interval (CI) = 46.7-81.9] in November 2017 (baseline) to 27.6 mg (95% CI = 19.2-36.0) in February 2019 (final time-point) was observed. A decline in the proportion of participants who met criteria for an opioid use disorder was also evident, with 51.2% (n = 133) at baseline relative to 33.3% (n = 58) at the 12-month follow-up. This study had an overall participant retention rate of 67% at the final time-point.

Re-scheduling codeine in Australia has been accompanied by significant reductions in codeine use and prevalence rates of opioid use disorder in a cohort of individuals who regularly use the medication, without apparent adverse impacts on pain or measures of anxiety and depression.