How strong is the evidence for benefit from take-home naloxone?: Findings from application of the Bradford Hill criteria

First published: 29 March 2019 | Last updated: 20 May 2019


Ms Rebecca McDonald

Rebecca McDonald is a PhD Student at the Addictions Department at King’s College London. Her doctoral research examines novel injection-free naloxone formulations for the prevention of opioid overdose. Rebecca holds an MSc in Clinical Psychology with concentration in behavioural neuroscience. She previously worked as Senior Research Assistant at the National Center on Addiction and Substance Abuse at Columbia University (USA) where she was involved in the implementation of SBIRT programs in primary care clinics as well as in the evaluation of a medication-assisted treatment initiative for uninsured and homeless opioid users. Rebecca served as consultant on the development of the 2014 WHO guidelines for the community management of opioid overdose.

Her employer (King’s College London) has registered intellectual property on a novel buccal naloxone formulation with which Rebecca is involved.

Opioid overdose is the biggest contributor to drug-related deaths, and overdose exceeds HIV, hepatitis, and other diseases as leading cause of death among injection users. Fatal outcome of opioid overdose is preventable through timely administration of naloxone, a potent antidote that rapidly reverses opioid-induced respiratory depression. Take-home naloxone provision directly to opioid users for emergency use has been proposed and recently implemented in communities in Europe, Asia, North America and Australia, albeit mostly as pilot schemes and without formal evaluation. In order to address this evaluation gap, a systematic review was carried out to assess the effectiveness of take-home naloxone programs.

Electronic databases were searched for English-language, peer-reviewed quantitative and mixed-method studies of take-home naloxone programs that trained opioid users in overdose prevention and reported on overdose outcomes.

Evidence was evaluated using the Bradford Hill’s criteria, a set of nine criteria to assess public health interventions when only observational data are available.

A total 1,397 records (1,187 after removal of duplicates) were retrieved, with 22 studies meeting the search criteria for analysis. Due to lack of randomized controlled trials, meta-analysis was dismissed in favor of narrative synthesis. From eligible studies, we find take-home naloxone meets at least seven of the nine Bradford Hill criteria.

The evidence from non-randomized studies finds that take-home naloxone programs lead to reduced overdose mortality among program participants and in the community and have a low rate of adverse events.

The full review can be read here

Funding: Rebecca McDonald is a recipient of the MRC/IoPPN Excellence studentship.


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