Objective To describe interventions to prevent and treat overdoses in the pre-hospital setting and review their effectiveness.

Design This review was undertaken in three stages: 1: systematic overview—systematic literature search for all reports of interventions to treat and prevent overdose in the pre-hospital setting; 2: systematic review—we selected comparative studies from the overview results and undertook qualitative synthesis; 3: we identified studies suitable for meta-analysis.

Setting We looked for interventions providing overdose reversal and/or prevention treatment in the prehospital emergency setting. UK opiate overdoses are amongst the highest in Europe. People who suffer a non-fatal poisoning are at high risk of death within the following year. For every death there are approximately 7 “near misses”. Naloxone is administered to reverse overdose.

Participants Drug users who overdose or are at risk of further overdose.

Main Outcome Measure Prevention of fatal overdose.

Results (1) Systematic overview—39 references described interventions in six categories: 1. take-home naloxone administered by peers to an overdose patient, following training; 2. CPR training for bystanders witnessing an overdose; 3. alternative routes of naloxone administration by health professionals(intranasal, subcutaneous, intramuscular, intravenous); 4. police attendance protocols to encourage 999 calls by peers witnessing overdose; 5. supervised injection facilities; 6. psychosocial/educational interventions. (2) Systematic review—15 studies were included. Populations, interventions, methods and outcome were heterogeneous but 10/15 contained at least one comparative result. Quality assessment scores identified 3/15 reasonable quality studies (1 RCT) but most were poor quality. Evidence of effectiveness was weak but suggested death rates may be reduced by: take-home naloxone; bystander CPR; treatment for addiction; naloxone implants. Inter-study results were not comparable. (3) Meta-analysis—we could not identify comparable results across such diverse studies. Meta-analysis of effectiveness was therefore not possible.

Conclusion There is little evidence of effectiveness for interventions identified in this review, including alternative pathways for naloxone administration, although naloxone is an effective treatment to reverse opiate overdose. Rigorous evaluation is needed to assess clinical and cost effectiveness, adverse event rates and effects on drug-taking behaviour of such approaches.