Opioid agonist treatment outcomes among individuals with a history of nonfatal overdose: Findings from a pragmatic, pan-Canadian, randomized control trial.

BACKGROUND AND OBJECTIVES: History of nonfatal overdose (NFO) is common among people who use opioids, but little is known about opioid agonist treatment (OAT) outcomes for this high-risk subpopulation. The objective of this study was to investigate the relative effectiveness of buprenorphine/naloxone and methadone on retention and suppression of opioid use among individuals with opioid use disorder (OUD) and history of NFO. METHODS: Secondary analysis of a pan-Canadian pragmatic trial comparing flexible take-home buprenorphine/naloxone and supervised methadone for people with OUD and history of NFO. Logistic regression was used to examine the impact of OAT on retention in the assigned or in any OAT at 24 weeks and analysis of covariance was used to examine the mean difference in opioid use between treatment arms. RESULTS: Of the 272 randomized participants, 155 (57%) reported at least one NFO at baseline. Retention rates in the assigned treatment were 17.7% in the buprenorphine/naloxone group and 18.4% in the methadone group (adjusted odds ratio [AOR] = 0.54, 95% CI: 0.17-1.54). Rates of retention in any OAT were 28% and 20% in the buprenorphine/naloxone and methadone arms, respectively (AOR = 1.55, 95% CI: 0.65-3.78). There was an 11.9% adjusted mean difference in opioid-free urine drug tests, favoring the buprenorphine/naloxone arm (95% CI: 3.5-20.3; p = .0057). CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE: Among adults with OUD and a history of overdose, overall retention rates were low but improved when retention in any treatment was considered. These findings highlight the importance of flexibility and patient-centered care to improve retention and other treatment outcomes in this population.

Correlates of nonfatal overdose among treatment-seeking individuals with non-heroin opioid use disorder: Findings from a pragmatic, pan-Canadian, randomized control trial.

INTRODUCTION: Misuse of prescription and synthetic opioids is a primary contributor to the escalating overdose crisis in North America. However, factors associated with nonfatal overdose (NFO) in this context are poorly understood. We examined individual and socio-structural level correlates of NFO among treatment-seeking adults with an opioid use disorder (OUD) not attributed to heroin (nonheroin opioid use disorder [NH-OUD]). METHODS: The study drew data from OPTIMA, a pan-Canadian, multicenter, pragmatic, two-arm randomized control trial comparing supervised methadone and flexible take-home dosing buprenorphine/naloxone models of care among adults with NH-OUD conducted between 2017 and 2020. We used bivariable and multivariable logistic regression to determine factors associated with a lifetime history of NFO among participants enrolled in the trial. RESULTS: Of 267 included participants, 154 (58%) reported a NFO in their lifetime, of whom 83 (55 %) had an NFO in the last 6 months. In multivariable analyses, positive urine drug test (UDT) for methamphetamine/amphetamine (Adjusted Odds Ratio [AOR] = 2.59; 95 % confidence interval [CI]: 1.17-5.80), positive UDT for fentanyl (AOR = 2.31; 95 % CI: 1.01-5.30), receiving income assistance (AOR = 2.17; 95 % CI: 1.18-4.09) and homelessness (AOR = 2.40; 95 % CI: 1.25-4.68) were positively associated with a lifetime history of NFO. CONCLUSIONS: We found a high prevalence of NFO history in treatment-seeking adults with NH-OUD, particularly among participants with certain drug use patterns and markers of socio-structural marginalization at the time of enrollment. Given the known impact of prior NFO on future harms, these findings highlight the need for comprehensive care approaches that address polysubstance use and social determinants of health to mitigate future overdose risk.

Examining fentanyl and its analogues in the unregulated drug supply of British Columbia, Canada using drug checking technologies.

INTRODUCTION: The emergence of fentanyl and its analogues have contributed to a drastic rise in overdose-related mortality in recent years. The objective of this study was to determine the number of drug checking samples containing fentanyl and fentanyl analogues using both point of care and confirmatory drug checking technologies. METHODS: Point-of-care drug checking data, using a combination of fentanyl immunoassay strips and Fourier-transform infrared spectroscopy (FTIR), were collected at harm reduction sites in Vancouver and Surrey, British Columbia. Based on current recommendations from the British Columbia Centre on Substance Use Drug Checking Project, a subset of these samples was sent for confirmatory analysis using quantitative nuclear resonance spectroscopy, gas chromatography-mass spectrometry and/or liquid chromatography-mass spectrometry. RESULTS: A total of 22,916 samples were tested using FTIR and fentanyl immunoassay strips, of which 6125 (29%) were positive for fentanyl and/or fentanyl analogues. FTIR identified a fentanyl analogue in five samples (all carfentanil). Of the 1467 samples sent for confirmatory analysis, fentanyl was identified in 855 (58%) and fentanyl analogues in 85 (6%), including: carfentanil (n = 56), acetyl fentanyl (n = 15), furanyl fentanyl (n = 9) and cyclopropyl fentanyl (n = 5). DISCUSSION AND CONCLUSION: Our research found that FTIR does not consistently distinguish between fentanyl and its analogues at point of care and that highly sensitive confirmatory drug checking technologies are needed to identify fentanyl analogues. These findings underscore the limitations of current drug checking technologies and the importance of using both point of care and confirmatory drug checking initiatives for monitoring changes in the drug supply.