Use of fentanyl test strips by people who inject drugs

Abstract

BACKGROUND: This study examines fentanyl test strip (FTS) use among people who inject drugs (PWID) in North Carolina and West Virginia and serves as a longitudinal follow-up to baseline findings from the South Atlantic Fentanyl Test Strip Study (SAFTSS). SAFTSS was established to investigate contemporaneous changes in FTS use and drug use behaviors among a rural cohort of PWID. The present analysis extends prior baseline findings by incorporating an additional 12 months of follow-up data to offer longitudinal insight into demographic and behavioral patterns of FTS use among rural PWID.

METHODS: We analyzed data from the same cohort described in Zibbell et al. (2024). Data was originally collected between June 2021 and March 2022, with additional post-baseline follow-up surveys conducted at 6 and 12 months. The primary outcome was past 30-day FTS use. We used mixed-effects logistic regression models to estimate the probability of past 30-day FTS use across the three survey waves. Models were estimated for both the full analytic sample and a complete case subsample.

RESULTS: Past 30-day FTS use declined over the 12-month follow-up period in both the full analytic sample (aOR = 0.642; p < 0.05) and the complete case sample (aOR = 0.557; p < 0.01). Currently unhoused participants had lower odds of FTS use in both samples (full sample aOR = 0.679; p < 0.05; complete cases aOR = 0.611; p < 0.05). In the full analytic sample, witnessing an overdose in the prior six months was strongly associated with higher odds of FTS use (aOR = 2.444; p < 0.001), and this association remained robust in the complete case analysis (aOR = 2.257; p < 0.001).

CONCLUSIONS: Observed declines in FTS use amongst the SAFTSS cohort at six and 12 months are consistent with baseline findings. Observed declines in fentanyl test strip use across the 12-month SAFTSS follow-up period suggests early uptake may not translate into sustained engagement in the late fentanyl era. Witnessing an overdose was strongly associated with FTS use throughout the entire study period. Participants who witnessed an overdose in the previous six months demonstrated substantially higher predicted probabilities of FTS use. These longitudinal findings reinforce baseline evidence that direct exposure to overdose events is a key motivator for engagement in harm reduction services among PWID.