Introduction: Death due to opioid overdose was declared a public health crisis in Canada in 2015. Traditionally, patients who have overdosed on opioids that are managed by emergency medical services (EMS) are treated with the opioid antagonist naloxone, provided ventilatory support and subsequently transported to hospital. However, certain EMS agencies have permitted patients who have been reversed from opioid overdose to refuse transport, if the patient exhibits capacity to do so. Evidence on the safety of this practice is limited. Therefore, our intent was to examine the available literature to determine mortality and serious adverse events within 48 hours of EMS treat and release due to suspected rebound opioid toxicity after naloxone administration.

Methods: A systematic search was performed on 11 May 2017 in PubMed, Cochrane Central, Embase and CINHAL. Studies that reported on the outcome of patients treated with prehospital naloxone and released at the scene were included. Analyses for incidence of mortality and adverse events at the scene were conducted. Risk of bias and assessment of publication bias was also done.

Results: 1401 records were screened after duplicate removal. Eighteen full-text studies were reviewed with seven selected for inclusion. None were found to be high risk of bias. In most studies, heroin was the source of the overdose. Mortality within 48 hours was infrequent with only four deaths among 4912 patients ﴾0.081%﴿ in the seven studies. Only one study reported on adverse events and found no incidence of adverse events from their sample of 71 released patients.

Conclusion: Mortality or serious adverse events due to suspected rebound toxicity in patients released on scene post-EMS treatment with naloxone were rare. However, studies involving longer-acting opioids were rare and no study involved fentanyl.

Competing interests: None declared.