Prevalence and longitudinal correlates of recent exposure to fentanyl among HIV-positive people who use unregulated drugs during a community-wide overdose crisis.

The United States and Canada are experiencing an opioid overdose crisis driven largely by exposure to fentanyl (a potent synthetic opioid), with little known about fentanyl exposure among HIV-positive people who use unregulated drugs (PWUD). We sought to estimate the prevalence and correlates of fentanyl exposure among a community-recruited sample derived from a prospective cohort study of HIV-positive PWUD in Vancouver, Canada. Generalized linear mixed-effects analyses were used to identify longitudinal factors associated with a fentanyl-positive urine drug screen test. Between June 2016-November 2017, 456 participants were recruited and contributed 1007 observations. At baseline, 96% of participants were ART-exposed, 72% had an HIV viral load (VL) <50 copies/mL and 21% had a fentanyl-positive test. Longitudinally, fentanyl-positive tests were characterized by: younger participant age (Adjusted Odds Ratio [AOR] = 0.45), recent non-fatal overdose (AOR = 2.30), engagement in opioid agonist therapy (AOR = 1.91), and at least daily heroin injection (AOR = 11.27). CD4+ cell count was negatively associated with fentanyl urine positivity (AOR = 0.92) (all  < 0.05). We identified several risk factors for overdose linked to fentanyl exposure among this sample, although no link with HIV treatment engagement or detectable HIV VL. Innovative strategies are needed to reduce the harmful effects of the contaminated unregulated drug supply experienced by PWUD.