Consumer discernment of fentanyl in illicit opioids confirmed by fentanyl test strips: Lessons from a syringe services program in North Carolina.

Background: The United States (U.S.) continues to witness an unprecedented increase in opioid overdose deaths driven by precipitous growth in the supply and use of illicitly-manufactured fentanyls (IMF). Fentanyl's growing market share of the illicit opioid supply in the U.S. has led to seismic shifts in the composition of the country's heroin supply. The growth in fentanyl supply has transformed illicit opioid markets once offering heroin with fairly consistent purity and potency to a supply overpopulated with fentanyl(s) of inconsistent and unpredictable potency. In response, people who inject drugs (PWID) have developed a number of sensory strategies to detect fentanyl in illicit opioids. The current study examined the accuracy of sensory discernment strategies by measuring study participants' descriptions of the last opioid injected and checked with a fentanyl test strip (FTS) by that test's positive/negative result. The primary objective was to determine associations between FTS results and descriptions of the illicit opioid's physical appearance and physiological effects.

Methods: Between September-October 2017, a total of 129 PWID were recruited from a syringe services program in Greensboro, North Carolina and completed an online survey about their most recent use of FTS. Participants were instructed to describe the appearance and effects associated with the most recent opioid they injected and tested with FTS. We conducted bivariate and multivariate analyses to determine differences in positive vs negative FTS results and the physical characteristics and physiological experiences reported. An exploratory analysis was also conducted to describe the types and bodily locations of unusual sensations experienced by PWID reporting positive FTS results.

Results: For physical characteristics, 32% reported that the drug was white before adding water and 38% reported the solution was clear after adding water. For physiological effects compared to heroin, 42% reported a stronger rush, 30% a shorter high, 30% a shorter time to the onset of withdrawal symptoms, and 42% experienced unusual sensations. In the multivariable model adjusting for demographics and polydrug correlates, white color of drug before adding water, stronger rush, shorter time to withdrawal, and unusual sensations were significantly associated with a positive FTS result. The most common unusual sensations were pins and needles (51%), warming of the head and face (35%), and lightheadedness (30%), and the most common locations where sensations occurred were face and neck (61%), arms/legs (54%), and chest (37%).

Conclusion: We found positive FTS results were significantly associated with the physical characteristics and physiological effects described by PWID. Descriptions concerning physical appearance were consistent with law enforcement profiles of illicitly-manufactured fentanyl and physiological effects were concomitant with scientific and clinical medical literature on iatrogenic fentanyl use. Taken together, these findings suggest sensory strategies for detecting fentanyl in illicit opioids may be an effective risk reduction tool to help consumers navigate unpredictable markets more safely.