Fentanyl abuse proportion in methadone maintenance treatment, and patients' knowledge about its risks

Fentanyl is not yet routinely monitored among methadone maintenance treatment (MMT) patients in Israel. We aimed 1. to evaluate urine fentanyl proportion changes over 3 years and characterize patients' characteristics 2. To study patients' self-report on fentanyl usage, and compare knowledge about fentanyl risk, before and following brief educational intervention.

Fentanyl in the urine of all current MMT patients was tested every 3 months year between 2021 and 2023, and patients with positive urine fentanyl were characterized. Current patients were interviewed using a fentanyl knowledge questionnaire (effects, indications, and risks) before and following an explanation session.

Proportion of fentanyl ranged between 9.8 and 15.1%, and patients with urine positive for fentanyl (September 2023) were characterized as having positive urine for pregabalin, cocaine, and benzodiazepine (logistic regression). Of the current 260 patients (87% compliance), 78(30%) self-reported of fentanyl lifetime use ("Ever"), and 182 "never" use. The "Ever" group had higher Knowledge scores than the "Never", both groups improved following the explanatory session (repeated measure). The "Ever" group patients were found with urine positive for cannabis and benzodiazepine on admission to MMT, they were younger, did not manage to gain take-home dose privileges and had a higher fentanyl knowledge score (logistic regression).

In the absence of routine fentanyl tests, a high knowledge score, shorter duration in MMT, benzodiazepine usage on admission, and current cannabis usage, may hint of the possibility of fentanyl abuse.