Julie Bruneau

Background and aims: The prevalence of chronic pain is elevated among people who inject drugs. Chronic pain may motivate drug use, potentially increasing the risk of non‐fatal overdose. We aimed to estimate the association between chronic pain and non‐fatal overdose in people who inject drugs. Design: Prospective cohort study of people who inject drugs recruited in community settings [the Hepatitis Cohort (HEPCO) study], with data collection every three months between August 2017 and November 2025. Setting: Montreal, Canada. Participants: Participants were people who inject drugs (past 6‐month injecting), aged 18 years or older, living in the greater Montreal area and speaking French or English. Measurements: The outcome was defined as having at least one non‐fatal overdose in the past 3 months, and the exposure was defined as experiencing chronic pain in the past 3 months. Covariates were age; gender; past 3‐month psychological distress (K10), housing status, opioid use, benzodiazepine use and opioid agonist treatment; past‐month days of alcohol use; and interview era (pre‐November 2020 vs. November 2020 onwards). A lagged analysis was conducted to explore temporality, based on chronic pain status reported at the visit preceding the outcome assessment. The analysis was not pre‐registered and the results should therefore be regarded as exploratory. Results: The primary analysis included 4790 study visits from 887 participants and 355 reports of non‐fatal overdose. At baseline, 81.4% of the sample was men, median age was 45 years and 46.8% reported chronic pain in the past 3 months. Chronic pain in the past 3 months was associated with a 40% increase in past 3‐month non‐fatal overdose [adjusted prevalence ratio (PR) = 1.40; 95% confidence interval (CI) = 1.13–1.75]. Similar results were observed in the lagged analysis (adjusted PR = 1.52, 95% CI = 1.18–1.96). Summary: In a Montreal, Canada, cohort of people who inject drugs, chronic pain was associated with experiencing non‐fatal overdose. We interpret this finding within a reciprocal model of pain and substance use, in which chronic pain increases the likelihood of using drugs in ways that increase overdose risk, and pain is potentiated by drug use and withdrawal.

Ongoing monitoring of hepatitis C virus (HCV) and HIV incidence among people who inject drugs (PWID) is important for epidemic control and assessing progress towards disease elimination. We estimated trends in HIV and HCV infection incidence in a community‐based cohort of PWID in Montreal, Canada. Data from March 2011 to March 2025 were drawn from the HEPCO study of PWID aged ≥ 18 years and living in Montreal. Participants with at least two visits were included in analyses. We used a random point approach to estimate the date of each infection event, imputing each date 1000 times, and Rubin's rules to pool incidence rates and 95% CIs across imputations. A total of 743 participants contributed to HCV analyses, with 152 infection events and incidence of 6.47 per 100 person‐years (p‐y) (95% CI 6.46–6.49). Incidence peaked in 2013 and declined to 2019 before increasing again post‐pandemic. There were 61 primary HCV infection events (incidence: 6.15 per 100 p‐y; 95% CI 4.79–7.90) and 91 reinfection events (incidence: 6.71 per 100 p‐y; 95% CI 6.69–6.73). A total of 836 participants contributed to HIV analysis, with only eight infections over 3089.89 p‐y (incidence: 0.26 per 100 p‐y; 95% CI 0.13–0.52). Declining HCV incidence among PWID in Montreal may have reversed, but limited data collection during the years 2020–2021 complicates interpretation. HIV incidence was persistently low. HCV incidence remains above World Health Organization elimination targets, highlighting the need for sustained investment in prevention and linkage to care for PWID.

The relationship between substance use and chronic pain is bidirectional. Although chronic pain and polysubstance use are highly prevalent among people who inject drugs (PWID), few studies have examined how the frequency of use of different substances relates to chronic pain. The aim of this study was to examine associations between substance use frequency and chronic pain in a sample of PWID. A cross-sectional analysis was conducted among PWID participating in a community-based cohort in Montreal, Canada. Chronic pain measures were introduced in the interviewer-administered questionnaire in February 2017. The first questionnaire was used for analyses, which covers data up to November 2022. Logistic regression analyses were conducted to examine associations between alcohol, stimulants, opioid and cannabis frequency and chronic pain. Six hundred and eight participants were included; 84% were men and mean age was 44.7 years old. Prevalence of chronic pain was 48%. Age (adjusted odds ratio [aOR] = 1.38, 95% confidence interval [CI] 1.15–1.65) and regular alcohol consumption in the past month (aOR = 1.76, 95% CI 1.13–2.75) were associated with chronic pain in univariable and multivariable logistic regression models. The frequency of use for all other substances was not found to be significantly associated with chronic pain. The prevalence of chronic pain in our sample was high. The positive association between high frequency of alcohol use and chronic pain could be explained by alterations of pain pathways by heavy use and withdrawal episodes, potentially increasing hyperalgesia. This study underscores the importance of addressing alcohol use along with other substances among PWID.

Impulsivity is a key contributor to substance use disorder, with previous research consistently demonstrating its role in the initiation, continuation and

Patient-centered approaches may facilitate retention in opioid agonist treatment (OAT) but are challenging to implement in rigid or stigmatizing service contexts. We evaluate a telemedicine program delivering flexible, patient-centered OAT from a community-based harm reduction setting in Montreal, Canada. An OAT clinic was established in a community-based harm reduction setting with hospital-based addiction medicine services delivered remotely via telemedicine. Community workers screened clients, established telemedicine connections, and offered holistic patient follow-up. The medical team offered individualized OAT and other health services. Patients chose between treatment with methadone, buprenorphine/naloxone, or slow-release oral morphine. Hydromorphone co-prescription was also available. Effectiveness was assessed via longitudinal chart review and semi-structured interviews (n = 20). A convergent mixed method design was used to quantify retention rates and blood borne infection care up to 12 month follow up, and to examine patient reported program experiences. Sixty-nine patients (46 men, 23 women; median age 38) initiated OAT between April 2020–March 2022. Most (96%) were injecting opioids, 56% were unstably housed, and 71% reported prior OAT. Patients typically initiated treatment with methadone (54%) or slow-release oral morphine (35%); 78% also received hydromorphone. Continuous retention in the first OAT episode was 83% at one month, 74% at three months, and 54% at 12 months. Disregarding prior treatment interruptions, 71% of patients were receiving OAT at 12 months. Most patients were assessed for HIV (77%) and HCV (78%), and 13/15 confirmed as HCV-positive initiated antiviral treatment. Trust, respect, and the alignment of practices with patient-centered care and harm reduction principles were critical to success. Integrating treatment within a community-based harm reduction setting enhanced accessibility and care coordination, and created a welcoming service environment. Diverse medication options, collaborative treatment planning, and a non-judgmental/non-punitive approach were key to developing positive therapeutic relationships. Our community-based telemedicine program presents a novel framework for OAT delivery that efficiently bridges the health and community sectors. Working collaboratively around the patient, program partners leveraged their strengths to improve treatment experiences and promote retention.

Impulsivity is closely implicated in substance use disorders; however, its definition and assessment among people who use illicit drugs (PWUD) are lacking consistency. This scoping review maps the existing evidence on how impulsivity has been defined, measured, and linked to drug use behaviours and consequences. A systematic search of manuscripts (1990–2025) was conducted across multiple databases, identifying 267 eligible studies. Behavioural tasks (76%) were more commonly used to measure impulsivity compared to self-reported tools (44%). The most frequently used behavioural tasks included the Iowa Gambling Task (26%) (cognitive, decision-making and risk-taking impulsivity) and the Go No-Go Task (23%) (motor impulsivity). Studies relying on self-reported measures primarily used the Barratt Impulsivity Scale (N = 86, 73%). Many studies assessed the association between impulsivity and drug use patterns (39%) and treatment-related variables (40%), with fewer examining risk behaviours (13%) and drug-related consequences (23%). Despite growing research, inconsistencies in impulsivity measurements hinder interpretation and comparability of findings. A universal measurement approach is needed to assess impulsivity in PWUD.

Background and aim: Urine drug testing is often utilized alongside opioid agonist treatment to assess client progress by validating self‐reported substance use, monitoring for diversion and supporting clinical decisions for take‐home dosing. However, there is a paucity of evidence to support the practice of urine drug testing. We aimed to determine the association of alternative urine drug testing frequencies with opioid agonist treatment discontinuation, compared with no monitoring, among individuals receiving methadone or buprenorphine/naloxone treatment. Design: Population‐based retrospective cohort study and target trial emulation based on nine‐linked administrative databases. Setting: British Columbia, Canada, between 1 January 2010 and 17 March 2020. Participants: Individuals with no history of cancer or palliative care, aged 18 or older and no indication of pregnancy who initiated methadone or buprenorphine/naloxone. A total of 18 988 methadone and 11 910 buprenorphine/naloxone recipients were included in the incident user design (individuals with no past opioid agonist treatment experience). Measurements: We used a clone‐censor‐weight approach to estimate hazard ratios with 95% compatibility (“confidence”) intervals for treatment discontinuation (lasting at least 5 and 6 days for methadone and buprenorphine, respectively) and all‐cause mortality on treatment within 12 months for static urine drug testing strategies. Findings: Under static monitoring strategies, weekly urine drug testing was associated with a slightly reduced risk of discontinuation in the first year of continuous retention in treatment [methadone: adjusted hazard ratio (aHR) = 0.96, 95% compatibility interval (CI) = (0.95–0.98); buprenorphine/naloxone: aHR = 0.95 (0.94–0.97)] compared with no monitoring. The estimated associations of weekly urine drug testing with all‐cause mortality were similar in size but extremely imprecise [methadone: aHR = 0.95 (0.78–1.15), buprenorphine/naloxone: aHR = 0.99 (0.62–1.58)]. Less frequent testing demonstrated no observed difference on treatment discontinuation or all‐cause mortality compared with no monitoring. Conclusion: Compared with no urine drug testing, weekly urine drug testing may be associated with improved opioid agonist treatment retention; however, the high costs attributable to frequent testing may not be cost‐effective and requires further evaluation. There was no improvement associated with less frequent testing compared with no monitoring.