The impact of codeine rescheduling on non-opioid analgesic use by people who regularly use codeine: a prospective cohort study.

Abstract

Background: Codeine was rescheduled in Australia to prescription only in February 2018. Initial studies reported an increase in population level paracetamol and ibuprofen sales following codeine upscheduling. However, to date no study has been able to investigate changes in non-opioid analgesic use at the individual patient level to determine if sales data reflect actual consumption patterns.

Aim: To address this gap, we aimed to determine the impact of codeine rescheduling on non-opioid analgesic use in people who regularly used over-the-counter codeine, primarily for pain, prior to the rescheduling change.

Method: We conducted a prospective cohort study with 260 participants who reported regular over-the-counter codeine consumption at cohort entry. Surveys were completed at baseline (November 2017, 3 months before rescheduling) and at 1 month (February 2018), 4 months (June 2018), and 12 months (February 2019), following rescheduling. The primary outcomes were mean daily doses of non-opioid analgesics, captured through a 7 day medication diary.

Results: The mean daily paracetamol dose decreased from 1754.4 mg (95% CI 1300.5-2208.3) at baseline to 1023.8 mg (95% CI 808.5-1239.1) at the final time-point (+ 12 months) (p = .009). The mean daily ibuprofen dose decreased from 305.1mg (95% CI 217.9-392.4) at baseline to 161.2 mg (95% CI 98.5-224.0) 12 months after rescheduling (p = .03). No significant change in doses of other medications remained was found.

Conclusion: In people who regularly consumed over-the-counter codeine, doses of non-opioid analgesics either reduced or remained stable following codeine rescheduling, suggesting concerns of medication substitution or overuse following the change were not realised.