Feasibility, consumer acceptability, and behavioural outcomes associated with take-home fentanyl test strips
Why did we undertake this study?
Fentanyl and fentanyl analogues pose an urgent public health threat. These substances are of higher potency than other opioids and have contributed to tens of thousands of deaths worldwide,particularly in North America.Most of these deaths appear to be the result of people unwittingly consuming substances that have been adulterated with illicitly manufactured fentanyl or fentanyl analogues.
To mitigate this risk,community-based organisationsstarted to utilize and distribute fentanyl test strips.These commercially available test strips detect fentanyl, related analogues and their metabolites in urine (i.e., post-consumption), however they can be used off-label to detect fentanyl and some fentanyl analogues indrug supplies (i.e., pre-consumption).Studies, predominantly conducted in North America, show high consumer acceptability of such a strategy, as well as the potential to result in behavioural changes that reduce overdose risk.
Thankfully, Australia has not yet witnessed the same magnitude of fentanyl-related overdoses, with most deathsinvolving the intravenous administration of fentanyl from transdermalpatches. Nevertheless,we have had clusters of deaths from‘fentanyl‐laced’substances and fentanyl analogues, as well aspublic health alertsregarding substances being adulterated with fentanyl or fentanyl analogues. It is therefore important that we are prepared to respond should similar trends start to emerge in Australia.
What did the study involve?
We recruited a total of 78 people who had used heroin in the past six months,from Kirketon Road Centre and Rankin Court, and provided a short training session on how to use the fentanyl test strips to test their drugs (or drugresidue), and how to interpret the results. Participantswere thengiven 10 fentanyl test strips to take home andwere followed up four weeks later(72 participants were followed-up; 92% follow-up rate).
What did we find?
Consumer acceptability of fentanyl test strips, and drug checking more broadly, was high.
We found that most participants (81%) had used at least one test strip by the time of the 4-week follow-up and had used a median of 6 strips. Virtually all participants viewed the strips favourably, reporting that would like to continue using the strips (97%), if they were free to access, and that they would recommend them to their peers (95%).Indeed, participants reporting giving away a total of 72 strips.
The majority (93%) of participants also reported that they would like to be able to access a drug checking service to have the contents and/or purity of their substances tested.
Findings regarding the feasibility of take-home fentanyl test strips were mixed.
On the one hand, the test strips are cheap (1USD per strip), and easy to use, with most participants reporting that they felt confident in their ability to use the strips (97%) and interpret the results(93%).
However, despite high levels of self-reported confidence, we have concerns that some results were misinterpreted.Of a total of342used test strips, 56 were self-reported to have returned a positive detection for fentanyl (not analytically verified), which was higher than expected. Given that there was no evidence of associated overdose, either among our participants, or from nearby services, we investigated this further, andfound that the second line (which indicates that fentanyl has not been detected) can be extremely faint (see examples below).This may have resulted in some negative results beingmisinterpreted as positive.
People reported changing their behaviour when they received, or thought they had received, a positive detection for fentanyl.
Of thosewho reported a positive fentanyl detection using the test strips (n=25),68% reported that they used less than they otherwise would have or started with a smaller amount. An additional 60% reported sharing this information with peers and/or health professionals, and 40% told their supplier. One-fifth (20%) reported using the test after they had already consumed the substance.
What is the overall take-home message?
People who use heroin want information about what their drugs contain,however are currently reliant on sub-optimal technologies.Fentanyl test strips cannot determine purity, do not distinguish between fentanyl and the myriad of fentanyl analogues, and have the potential to be misinterpreted.
More recently, it has been suggested that a faint second line may be indicative of a positive or ‘faintly positive’ result. This contrasts with current advice that the presence of any second line, no matter how faint, is a negative result, as well as with other studies whichfound that a faint second line was a genuine negative result. This discrepancy is concerning, and further research is needed to determine how a faint second line should be interpreted.
In the meantime, these limitations could be overcome by providing access to more advanced drug checking technologies, with parallel provision of harm reduction information.