Effectiveness of interventions designed to increase safe medicine disposal: a systematic review and meta-analysis of randomised trials.

Background: Drug-related harm is a major cause of mortality, poisonings, hospitalisations and misuse. Reducing the availability of unused medicines is a component of ensuring medication safety. However, the current literature on how to increase the implementation of medicine disposal strategies needs to be clarified. This systematic review evaluated the effectiveness of strategies designed to promote medicine disposal.

Methods: Electronic databases and clinical trial registries were searched from inception to 16th February 2024 without restriction for randomised trials of any interventions aiming to increase medicine disposal compared to any control. Medicine disposal could be done using any method as reported by eligible studies. The primary outcome was the change in the proportion of participants who disposed of unused medicines. Secondary outcomes were changes in patient (e.g. knowledge of disposal strategies), population (e.g. poisonings), environmental (e.g. preventing going to landfill) and economic (e.g. cost-effectiveness) outcomes. The original Cochrane tool was used to assess the risk of bias. Random-effects meta-analysis was conducted on the primary outcome, and a narrative synthesis was performed on secondary outcomes due to heterogeneity. Grading of Recommendations Assessment, Development and Evaluation (GRADE) was used to assess the quality of evidence. PROSPERO registration: CRD42023491797.

Results: Eighteen randomised trials were included (plus five ongoing, registered trials). All studies were conducted in North America, published from 2016 to 2023, targeted opioid analgesic disposal and included 5347 participants. Interventional strategies of providing disposal kits (risk ratio [RR] 1.42, 95% confidence Interval [CI] 1.13 to 1.79, moderate evidence), education alone (RR 1.47, 95% CI 1.03 to 2.09, low evidence), education plus reminder prompts (RR 2.51, 95% CI 1.30 to 4.83, moderate evidence) and education plus disposal kits (RR 2.00, 95% CI 1.03 to 3.87, moderate evidence) increased disposal compared to routine practice. Secondary outcomes were infrequently reported, including no studies reporting population-level (poisonings, hospitalisations) and environmental outcomes.

Conclusions: There is moderate quality of evidence supporting interventions of disposal kits, disposal kit and education and education with text reminders to increase the disposal of unused medicines compared to routine practice. The conclusions of this review should be interpreted following consideration on the quality of evidence and the number of trials conducted.