An observational prospective cohort study of naloxone use at witnessed overdoses, Kazakhstan, Kyrgyzstan, Tajikistan, Ukraine.

Objective: To determine whether participation in the United Nations Office on Drugs and Crime (UNODC) and the World Health Organization's (WHO) Stop Overdose Safely (S-O-S) take-home naloxone training project in Kazakhstan, Kyrgyzstan, Tajikistan and Ukraine resulted in naloxone use at witnessed opioid overdoses. Methods: An observational prospective cohort study was performed by recruiting participants in the implementation of the S-O-S project, which was developed as part of the broader S-O-S initiative. Training included instruction on overdose responses and naloxone use. Study participants were followed for 6 months after completing training. The primary study outcome was participants' naloxone use at witnessed overdoses, reported at follow-up. Findings: Between 400 and 417 S-O-S project participants were recruited in each country. Overall, 84% (1388/1646) of participants were interviewed at 6-month follow-up. The percentage who reported witnessing an overdose between baseline and follow-up was 20% (71/356) in Tajikistan, 33% (113/349) in Kyrgyzstan, 37% (125/342) in Ukraine and 50% (170/341) in Kazakhstan. The percentage who reported using naloxone at their most recently witnessed overdose was 82% (103/125) in Ukraine, 89% (152/170) in Kazakhstan, 89% (101/113) in Kyrgyzstan and 100% (71/71) in Tajikistan. Conclusion: Implementation of the UNODC-WHO S-O-S training project in four low- to middle-income countries resulted in the reported use of take-home naloxone at around 90% of witnessed opioid overdoses. The percentage varied between countries but was generally higher than found in previous studies. Take-home naloxone is particularly important in countries where emergency medical responses to opioid overdoses may be limited.