Aqueous biphasic systems developed with deep eutectic solvents and polymer for the efficient extraction of pigments from beverages.

Novel aqueous biphasic systems (ABSs) developed with benzyl-based quaternary ammonium salts-deep eutectic solvents (DESs) and polypropylene glycol (PPG) were herein proposed. The liquid-liquid equilibrium and the partitioning behavior of pigments in the systems were addressed. The results suggested that the shorter the carbon chain length of the DES, the easier to form two phases. The analysis of mixed samples showed that the selective separation was achieved in the ABSs, including 99.47% of tartrazine in the DES-rich phase and 98.47% of sudan III in the PPG-rich phase. Additionally, the systems were successfully applied to the extraction of pigments from the actual beverage samples with recoveries ranging from 93.43% to 102.15%. Furthermore, the study on the separation mechanism indicated that the hydrogen bonding played a significant role in the separation process. All the above results highlight the proposed DES/polymer-based ABSs have great advantages in selective and high-performance separation of pigments from beverages.

Fentanyl Concentration in Drug Checking Samples and Risk of Overdose Death in Vancouver, Canada.

INTRODUCTION: The proliferation of fentanyl and its analogs in illegal, unregulated drug markets remains a major driver of the overdose crisis in North America. Drug checking services have been implemented as a harm reduction strategy to address the crisis. However, little is known about their potential utility as a mechanism for monitoring population-level risk of overdose stemming from changing fentanyl concentration in unregulated drugs over time. Therefore, this study assessed the relationship between median fentanyl concentration in expected opioid drug checking samples and the death rate due to illicit drug toxicity over time in Vancouver, Canada. METHODS: Monthly population-based rates of death due to illicit drug toxicity were drawn from provincial coroner records. Monthly median percent fentanyl concentration was calculated using a validated quantification model from point-of-care Fourier-transform infrared spectra among expected opioid samples that tested positive for fentanyl at community drug checking services. A time-series analysis using generalized additive modeling was conducted to examine the association between monthly median fentanyl concentration and monthly death rate due to illicit drug toxicity, controlling for calendar month. Analyses were conducted in 2021-2022. RESULTS: Between January 2019 and October 2020, 577 deaths due to illicit drug toxicity occurred in Vancouver, and the observed monthly rate ranged from 1.75 to 7.65 deaths per 100,000 population. A significant, positive association was observed between monthly median fentanyl concentration and monthly death rate due to illicit drug toxicity, adjusting for calendar month (chi-square=52.21, p<0.001). CONCLUSIONS: Findings suggest a role for point-of-care drug checking as a tool for monitoring evolving overdose risk at the population level.

Factors Associated With Abrupt Discontinuation of Long-Term High-Dose Opioid Treatment.

This cohort study investigates factors associated with abrupt discontinuation of long-term high-dose opioid treatment at the national level and across US states.

The association between longitudinal trends in receipt of buprenorphine for opioid use disorder and buprenorphine-waivered providers in the United States.

AIMS, DESIGN AND SETTING: We sought to describe longitudinal trends in buprenorphine receipt and buprenorphine-waivered providers in the United States from 2003 to 2021 and measure whether the relationship between the two differed after capacity-building strategies were enacted nationally in 2017. This was a retrospective study of two separate cohorts covering the years 2003-21, testing whether the association between two trends in these cohorts changed comparing 2003 to 2016 and from 2017 to 2021, among buprenorphine providers in the United States, regardless of treatment setting. Patients receiving dispensed buprenorphine at retail pharmacies. PARTICIPANTS: All providers who have obtained a waiver to prescribe buprenorphine in the United States, and an estimate of the annual number of patients who had buprenorphine for opioid use disorder (OUD) dispensed to them at a retail pharmacy. MEASUREMENTS: We synthesized and summarized data from multiple sources to assess the cumulative number of buprenorphine-waivered providers over time. We used national-level prescription data from IQVIA to estimate annual buprenorphine receipt for OUD. FINDINGS: From 2003 to 2021, the number of buprenorphine-waivered providers in the United States increased from fewer than 5000 in the first 2 years of Food and Drug Administration (FDA) approval to more than 114 000 in 2021, while patients receiving buprenorphine products for OUD increased from approximately 19 000 to more than 1.4 million. The strength of association between waivered providers and patients is significantly different before and after 2017 (P < 0.001). From 2003 to 2016, for each additional provider, there was an average increase of 32.1 [95% confidence interval (CI) = 28.7-35.6] patients, but an increase of only 4.6 (95% CI= 3.5-5.7) patients for each additional provider, beginning in 2017. CONCLUSIONS: In the United States, the relationship between the rates of growth in buprenorphine providers and patients became weaker after 2017. While efforts to increase buprenorphine-waivered providers were successful, there was less success in translating that into significant increases in buprenorphine receipt.

Comprehensive needle and syringe program and opioid agonist therapy reduce HIV and hepatitis c virus acquisition among people who inject drugs in different settings: A pooled analysis of emulated trials.

BACKGROUND AND AIMS: Although the Netherlands, Canada and Australia were early adopters of harm reduction for people who inject drugs (PWID), their respective HIV and hepatitis C (HCV) epidemics differ. We measured the pooled effect of needle and syringe program (NSP) and opioid agonist therapy (OAT) participation on HIV and HCV incidence in these settings. DESIGN: For each cohort, we emulated the design and statistical analysis of a target trial using observational data. SETTING AND PARTICIPANTS: We included PWID at risk of HIV or HCV infection from the Amsterdam Cohort Studies (1985-2013), Vancouver Injection Drug Users Study (1997-2009) and Melbourne Injecting Drug User Cohort Study (SuperMIX) (2010-2021). MEASUREMENTS: Separately for each infection and cohort (only HCV in SuperMIX), marginal structural models were used to compare the effect of comprehensive (on OAT and 100% NSP coverage or on OAT only if no recent injection drug use) versus no/partial NSP/OAT (no OAT and/or <100% NSP coverage) participation. Pooled hazard ratios (HR) and 95% CI were calculated using random-effects meta-analysis. FINDINGS: We observed 94 HIV seroconversions and 81 HCV seroconversions among 2023 and 430 participants, respectively. Comprehensive NSP/OAT led to a 41% lower risk of HIV acquisition (pooled HR = 0.59, 95% CI = 0.36-0.96) and a 76% lower risk of HCV acquisition (pooled HR = 0.24, 95% CI = 0.11-0.51), compared with no/partial NSP/OAT, with little heterogeneity between studies for both infections (I2  = 0%). CONCLUSIONS: In the Netherlands, Canada and Australia, comprehensive needle and syringe program and opioid agonist therapy participation appears to substantially reduce HIV and hepatitis C acquisition compared with no or partial needle and syringe program/opioid agonist therapy participation. These findings from an emulated trial design reinforce the critical role of comprehensive access to harm reduction in optimizing infection prevention for people who inject drugs.

Factors associated with patient perceived suboptimal dosing of in-hospital opioid agonist therapy among people who use illicit drugs in Vancouver, Canada.

Optimal dosing of opioid agonist therapy (OAT) is essential for treatment success. However, initiation and maintenance of OAT in hospital settings can be challenging given differing levels of opioid tolerance, withdrawal, and intoxication among patients.The objective of this study was to characterize the prevalence and factors associated with in-hospital patient perceived suboptimal OAT dosing among people who use illicit drugs (PWUD) in Vancouver, Canada.Data were derived from three prospective cohorts of PWUD in Vancouver, Canada. Bivariable and multivariable logistic regression models were used to examine factors associated with patient perceived suboptimal in-hospital OAT dose.273 study participants were prescribed OAT while in hospital: 83 (30.4%) participants perceived their OAT dose to be suboptimal. In a multivariable model, factors positively associated with a perceived suboptimal OAT dose included: homelessness (adjusted odds ratio [AOR] = 2.85; 95% CI: 1.53-5.28), daily stimulant use (AOR = 2.03; 95% CI: 1.14-3.63) and illicit drug use while in hospital (AOR = 2.33; 95% CI: 1.31-4.16).Almost one third of participants perceived receiving a suboptimal OAT dose while in hospital. These observed correlations indicate that a patient's perception of suboptimal OAT dosing in hospital may be more prevalent for patients who are homeless, report polysubstance use with stimulants and opioids and who obtain illicit drugs while hospitalized. While cautious prescribing of OAT in patients experiencing hospitalization is important, these findings demonstrate a high prevalence of and apparent risk factors for perceived suboptimal OAT dosing.

A Hospital-based Managed Alcohol Program in a Canadian Setting.

OBJECTIVES: A managed alcohol program (MAP) is a harm reduction strategy that provides regularly, witnessed alcohol to individuals with a severe alcohol use disorder. Although community MAPs have positive outcomes, applicability to hospital settings is unknown. This study describes a hospital-based MAP, characterizes its participants, and evaluates outcomes. METHODS: A retrospective chart review of MAP participants was conducted at an academic hospital in Vancouver, Canada, between July 2016 and October 2017. Data included demographics, alcohol/substance use, alcohol withdrawal risk, and MAP indication. Outcomes after MAP initiation included the change in mean daily alcohol consumption and liver enzymes. RESULTS: Seventeen patients participated in 26 hospital admissions: 76% male, mean age of 54 years, daily consumption prehospitalization of a mean 14 alcohol standard drinks, 59% reported previous nonbeverage alcohol consumption, and 41% participated in a community MAP. Most participants were high risk for severe, complicated alcohol withdrawal and presented in moderate withdrawal. Continuation of community MAP was the most common indication for hospital-based MAP initiation (38%), followed by a history of leaving hospital against medical advice (35%) and hospital illicit alcohol use (15%). Hospital-based MAP resulted in a mean of 5 fewer alcohol standard drinks daily compared with preadmission ( P = 0.002; 95% confidence interval, 2-8) and improvement in liver enzymes, with few adverse events. CONCLUSIONS: Participation in a hospital-based MAP may be an effective safe approach to reduce harms for some individuals with severe alcohol use disorder. Further study is needed to understand who benefits most from hospital-MAP and potential benefits/harms following hospital discharge.

Methadone Maintenance Treatment Discontinuation Among Young People who use Opioids in Vancouver, Canada.

OBJECTIVE: Retaining adolescents and young adults (AYA) in medications for opioid use disorder (MOUD), like methadone maintenance treatment (MMT), is critical to reducing toxic drug fatalities. This analysis sought to identify factors associated with MMT discontinuation among AYA. METHOD: Data were derived from the At-Risk Youth Study, a prospective cohort study of street-involved AYA in Vancouver, Canada, between December 2005 and June 2018. Multivariable extended Cox regression identified factors associated with time to MMT discontinuation among AYA who recently initiated MMT. In subanalysis, multivariable extended Cox regression analysis identified factors associated with time to "actionable" MMT discontinuation, which could be addressed through policy changes. RESULTS: A total of 308 participants reported recent MMT during the study period. Participants were excluded if they reported MMT in the past 6 months at baseline and were retained in MMT (n = 94, 30.5%); were missing MMT status data (n = 43, 14.0%); or completed an MMT taper (n = 11, 3.6%). Of the remaining 160 participants who initiated MMT over the study period, 102 (63.8%) discontinued MMT accounting for 119 unique discontinuation events. In multivariable extended Cox regression, MMT discontinuation was positively associated with recent weekly crystal methamphetamine use (adjusted hazard ratio [AHR] = 1.67, 95% confidence interval [CI]: 1.19 to 2.35), but negatively associated with age of first "hard" drug use (per year older) (AHR = 0.95, 95% CI: 0.90 to 1.00) and female sex (AHR = 0.66, 95% CI: 0.44 to 0.99). In subanalysis, recent weekly crystal methamphetamine use (AHR = 4.61, 95% CI: 1.78 to 11.9) and weekly heroin or fentanyl use (AHR = 3.37, 95% CI: 1.21 to 9.38) were positively associated with "actionable" MMT discontinuation, while older age (AHR = 0.87, 95% CI: 0.76 to 0.99) was negatively associated. CONCLUSIONS: Efforts to revise MMT programming; provide access to a range of MOUD, harm reduction, and treatments; and explore coprescribing stimulants to AYA with concurrent stimulant use may improve treatment retention and reduce toxic drug fatalities.

Racial and Ethnic Disparities in Buprenorphine Treatment Duration in the US.

This cohort study examines racial and ethnic differences in the duration of buprenorphine treatment for opioid use disorder in the US from 2006 to 2020.

Predictors of crystal methamphetamine use initiation or re-initiation among people receiving opioid agonist therapy: A prospective cohort study.

BACKGROUND: In the context of the ongoing opioid crisis in the United States and Canada, opioid agonist therapy (OAT) is the first-line treatment for opioid use disorder. However, there is growing concern regarding the increasing methamphetamine use among those on OAT, as well as the impact of such use may have on OAT retention and outcomes. We sought to identify the predictors of crystal methamphetamine initiation or re-initiation among people on OAT, in order to facilitate the development of effective preventive strategies. METHODS: We employed multivariable generalized estimating equations to identify the predictors of crystal methamphetamine use initiation or re-initiation among those who were on OAT within two prospective cohorts in Vancouver, Canada between 2005 and 2020. RESULTS: Of the 1281 participants receiving OAT, the median age was 43 years, and 59.2 % were male at baseline. During study follow-up, 564 (44.0 %) initiated or re-initiated crystal methamphetamine use while receiving OAT. In a multivariable model, a higher crystal methamphetamine use initiation or re-initiation rate was positively associated with younger age, unstable housing, unprotected sex, history of crystal methamphetamine use, as well as recent cocaine, prescription opioid, and unregulated opioid use (all p < 0.05). CONCLUSIONS: We identified high and increasing rates of crystal methamphetamine use initiation or re-initiation among our sample of people on OAT. Intervention strategies including housing program referral, sexual risk reduction, and integrated treatment approaches targeting polysubstance use are urgently needed to reduce the risks associated with methamphetamine use as well as the co-use of methamphetamine and opioids.

Factors associated with perceived decline in the quality of drugs during the COVID-19 pandemic: Evidence from community-recruited cohorts of people who use drugs in Vancouver, Canada.

OBJECTIVES: Driven by an increasingly toxic drug supply, drug toxicity deaths in the United States and Canada have risen to unprecedented levels during the COVID-19 pandemic. This study aimed to characterize the prevalence of and the factors associated with a perceived decline in the quality of drugs during the COVID-19 pandemic among community-recruited cohorts of PWUD in Vancouver, Canada. METHODS: Data collection took place between July and November 2020. In adherence with COVID-19 safety protocols, questionnaires were administered by interviewers through remote means (e.g., phone or videoconference). Using multivariable logistic regression, we characterized the prevalence of and factors associated with a perceived decline in drug quality during the start of the COVID-19 pandemic in Vancouver, Canada. RESULTS: Of the 738 individuals included in this analysis, 272 (36.9%) reported that the quality of drugs declined during the COVID-19 pandemic. In multivariable analysis, perceived decline in the quality of drugs was significantly associated with: recent non-fatal overdose (adjusted odds ratio [AOR]=2.01, 95% Confidence Interval [CI]: 1.29-3.15), at least weekly injection drug use (AOR=1.94, 95% CI: 1.40-2.71), at least weekly crack use (AOR=1.61, 95%CI: 1.10-2.36), and at least weekly crystal methamphetamine use (AOR=1.46, 95%CI: 1.03-2.08). DISCUSSION: Over a third of PWUD perceived that the quality of drugs declined during the COVID-19 pandemic and these individuals were significantly more likely to report experiencing a recent non-fatal overdose, engaging in frequent injection drug and stimulant use. Study findings indicate the need for interventions to address the toxic drug supply, including providing a regulated supply.

Impact of the international collaborative addiction medicine research fellowship on physicians' future engagement in addiction research.

Background: To evaluate how an international one-year intensive research training program for addiction medicine physicians contributed to subsequent research involvement and productivity. Methods: We prospectively compared addiction medicine physician fellows admitted to a one-year training program with non-admitted controls, using baseline questionnaire and peer-reviewed publication data. Participants' publication activity was assessed from fellowship application date onwards using biomedical databases (e.g., PubMed, Embase). Results: Between July 2014 and June 2020, which is six years of cohorts, 56 (39 women) physicians, both fellows (n = 25) and non-admitted applicants (n = 31), were observed and included in the study, contributing 261 person-years of observation. At baseline, in the fellows' cohort: 76% of participants (19/25) reported past research involvement, 24% (6/25) had one or more advanced graduate degrees (e.g., MPH), and the median number of peer-reviewed, first author publications was one (Interquartile Range [IQR] = 0-2). At baseline, in the controls' cohort: 84% of participants (26/31) reported past research involvement, 39% (12/31) had one or more advanced graduate degrees, and the median number of peer-reviewed, first author publications was zero. The physicians' training included internal medicine (n = 8), family medicine (n = 33), psychiatry (n = 5) and others (n = 4). At follow up, there was a significant difference between fellows (n = 25) and controls (n = 31) in total number of publications (Rate Ratio [RR] = 13.09, 95% Confidence Interval [CI], 5.01 - 34.21, p < 0.001), as well as first author publications (RR = 5.59, 95% CI, 2.23 - 14.06, p < 0.001). Conclusion: In the six-year observation period, fellows' productivity indicates undertaking this fellowship was associated with significant research outputs in comparison to controls, signaling successful training of addiction physicians to help recruit addiction medicine physicians to participate in addiction research.

Crystal methamphetamine use subgroups and associated addiction care access and overdose risk in a Canadian urban setting.

OBJECTIVES: Methamphetamine use is rising globally and we have limited treatments for this. Subgroups within the diverse methamphetamine-using population may have distinct treatment needs. Among a community-recruited sample of people who use crystal methamphetamine, we aimed to identify subgroups and characterize their overdose risk and access to addiction care. METHODS: Data from prospective cohorts of people who use drugs in Vancouver, Canada from 2014 to 2018 were used to conduct a repeated measures latent class analysis among participants who used crystal methamphetamine. Multivariable generalized estimating equations models were fit to determine the associated factors. RESULTS: Among 824 eligible participants, a five-class model was identified as the best fit: (1) primary stimulant use (15.7%); (2) women engaged in sex work and opioid use (21.4%); (3) street income generation and opioid use (31.6%); (4) opioid agonist therapy (OAT) patients (22.3%); and (5) men who have sex with men (9.0%). In multivariable analyses, compared to the primary stimulant use group, non-fatal overdose was positively associated with street income generation (adjusted odds ratio [AOR] = 1.49, 95% confidence interval [95% CI]=1.30-1.71), sex work (AOR = 1.38, 95% CI=1.20-1.59) and OAT (AOR = 1.22, 95% CI=1.06-1.41) subgroups; engagement in non-OAT addiction care was negatively associated with street income generation (AOR = 0.81, 95% CI=0.68-0.97) and sex work (AOR = 0.78, 95% CI=0.63-0.98) subgroups. DISCUSSION: Socioeconomically marginalized subgroups with opioid and crystal methamphetamine co-use were at highest risk of non-fatal overdose and had poorer access to addiction care, highlighting the need for tailored interventions.

Educational Studies Examining Knowledge of Substance Use Disorders and Career Aspirations Among Medical Trainees in an Inner-City Hospital.

OBJECTIVES: Gaps in addiction medicine training are a reason for poor substance use care in North America. Hospital addiction medicine consult services (AMCS) provide critical medical services, including screening and treatment of substance use disorders. Although these programs often feature an educational component for medical learners, the impact of AMCS teaching on objective knowledge and career aspirations in addiction medicine has not been well described. METHODS: The authors report findings from two sequential studies conducted at a large academic hospital in Vancouver, Canada. The first study assessed the impact of an AMCS clinical rotation on medical trainee addiction medicine objective knowledge using an online survey of 6 true/false questions before and after the rotation. The second study examined the impact of an AMCS rotation on career aspirations using 4 seven-point Likert-type questions. One-sample t tests on mean differences (MD) with Benjamini-Hochberg adjustment for multiple comparisons were employed for statistical analyses. RESULTS: Between May 2017 and June 2018, knowledge scores were significantly higher postrotation (MD = 4.78, standard deviation [SD] = 19.5, P = 0.034) among 115 medical trainees. Between July 2018 and July 2019, aspirations to practice addiction medicine were significantly more favorable postrotation (MD = 3.48, SD = 3.15, P < 0.001) among 101 medical trainees. CONCLUSIONS: AMCS rotations appear to improve addiction medicine knowledge and aspirations to practice addiction medicine among medical trainees. Larger-scale evaluations and outcomes research on integrating substance use disorders teaching in these settings will help move the discipline forward.

[Clinical characteristics and molecular genetics of seven neonates with congenital nephrogenic diabetes insipidus].

OBJECTIVE: To explore the clinical characteristics, genetic basis and clinical treatment of seven neonates with congenital nephrogenic diabetes insipidus (NDI). METHODS: Clinical data of the patients were collected. High-throughput sequencing was carried out to detect potential variants. Sanger sequencing was used to verify the results. RESULTS: The patients were all males, with the age of onset being 10 to 21 days. All patients were admitted to the hospital for intermittent fever as the first symptom during the neonatal period. Additional symptoms had included polydipsia and polyuria. After the treatment, 5 patients had recovered, the remainders still had NDI symptoms and developmental retardation. Five children were found to harbor pathogenic variants of the AVPR2/AQP2 gene, which included one in-frame mutation of c.645_646insGCACCTACCCTGGGTATCGCC, two missense mutations of c.541C>T and c.419C>A, and two hemizygous deletions of the AVPR2/AQP2 gene. Among these, two were unreported previously. Cases 6 and 7 were a pair of twins. Both had carried homozygous missense variants of c.538G>A of the AVPR2/AQP2 gene, which was known to be pathogenic. CONCLUSION: AVPR2/AQP2 is the main pathogenic gene for congenital NDI, for which two novel pathogenic variants have been discovered in this study. Above results have provided a basis for clinical diagnosis and genetic counseling for the affected pedigrees.

Migration Patterns from an Open Illicit Drug Scene and Emergency Department Visits among People Who Use Illicit Drugs in Vancouver, Canada.

BACKGROUND: People who use illicit drugs (PWUD) experience various adverse health outcomes leading to increased healthcare service utilization. PWUD are also a highly mobile population which poses challenges to healthcare delivery. The objective of this study was to identify migration patterns from the Downtown Eastside (DTES), an urban illicit drug scene in Vancouver and to estimate the impact of different migration patterns on two outcomes: a) emergency department (ED) visits and b) ED visits resulting in inpatient admission among PWUD. METHODS: Three prospective cohorts of PWUD in Vancouver were linked with regional ED data. We defined the optimal number of trajectory groups that best represented distinct patterns of migration from Vancouver's DTES using a latent class growth analysis. Then, generalized estimating equations were used to estimate the effect of migration patterns on the two ED outcomes. RESULTS: Four distinct migration trajectory patterns were identified among the 1210 included participants: PWUD who consistently lived in the DTES, those who migrated out of DTES early, those who migrated out of DTES late, and those who frequently revisited the DTES. Participants who frequently revisited the DTES had higher odds of an ED visit (adjusted odds ratio = 1.62; 95% confidence interval: 1.28-2.06). There was no significant association between migration patterns and inpatient admission. CONCLUSIONS: We found that PWUD who frequently revisited the DTES were more likely to have utilized the ED, suggesting that there may be a subgroup of PWUD who are at increased risk of experiencing negative health outcomes.Supplemental data for this article is available online at 10.1080/10826084.2021.1958849.

The impact of PSTD on service access among people who use drugs in Vancouver, Canada.

BACKGROUND: Settings throughout the United States and Canada are contending with high rates of drug-related overdose. This in turn has prompted efforts to more effectively engage people who use drugs (PWUD) in treatment and care. However, while co-morbid mental disorders are prevalent among PWUD and can undermine access to services, the impact of post-traumatic stress disorder (PTSD) on service access is not known. Therefore, we sought to assess whether PTSD is associated with difficulties accessing health and social services among PWUD in Vancouver, Canada. METHODS: Survey data was derived from two prospective cohorts of PWUD in Vancouver, Canada for the period of April 2017 to November 2018. PTSD was assessed using the PTSD Checklist for the DSM-V (PCL-5). Generalized estimating equations (GEE) was used to estimate the relationship between PTSD and self-reported inability to access health and social services, after adjustment for confounders. RESULTS: Among 810 participants included in our analysis, 316 (39.0%) participants qualified for a provisional PSTD diagnosis, and 117 (14.4%) reported difficulties accessing services. In a multivariable GEE analysis, a PTSD diagnosis (adjusted odds ratio = 1.69, 95% confidence interval: 1.12-2.55) was independently associated with difficulties accessing services. CONCLUSIONS: We found high rates of PTSD and self-reported difficulties accessing services among PWUD in Vancouver, as well as a positive association between PTSD and difficulties with service access. These findings highlight the need for trauma-informed approaches to service delivery for PWUD, as well as enhanced provider training specific to PTSD.

Frequent Cannabis Use Is Negatively Associated with Frequency of Injection Drug Use Among People Who Inject Drugs in a Canadian Setting.

Objectives: High levels of morbidity and mortality associated with injection drug use continue to represent a significant public health challenge in many settings worldwide. Previous studies have shown an association between cannabis use and decreased risk of some drug-related harms. We sought to evaluate the association between high-intensity cannabis use and the frequency of injection drug use among people who inject drugs (PWID). Methods: The data for this analysis were collected from three prospective cohorts of PWID in Vancouver, Canada, between September 2005 and May 2018. Generalized linear mixed-effects models were used to analyze the association between daily cannabis use and the frequency of injecting illegal drugs (i.e., self-reported average number of injections per month). Results: Among the 2,619 active PWID, the frequency of injection drug use was significantly lower among people who use cannabis daily compared with people who use it less than daily (adjusted odds ratio [AOR]=0.84, 95% confidence interval [CI]: 0.73-0.95). Sub-analyses indicated that this effect was restricted to the frequency of illegal opioid injection (AOR=0.78, 95% CI: 0.68-0.90); the association between daily cannabis use and the frequency of illegal stimulant injection was not significant (AOR=1.08, 95% CI 0.93-1.25). Discussion: The findings from these prospective cohorts suggest that people who use cannabis daily were less likely to report daily injection of illegal drugs compared with people who use it less than daily. These results suggest the potential value of conducting experimental research to test whether controlled administration of cannabinoids impacts the frequency of illegal opioid injection among PWID.

Awareness of fentanyl exposure and the associated overdose risks among people who inject drugs in a Canadian setting.

INTRODUCTION: Illicitly manufactured fentanyl continues to fuel the opioid overdose crisis throughout the USA and Canada. However, little is known about factors associated with knowingly or unknowingly using fentanyl. Therefore, we sought to identify the prevalence and correlates of suspected/known and unknown exposure to fentanyl (excluding the prescribed one) among people who inject drugs (PWID), including associated overdose risks. METHODS: Data were derived from three prospective cohort studies of community-recruited people who use drugs in Vancouver, Canada in 2016-2017. Multivariable logistic regression was used to identify correlates of suspected/known exposure (i.e. urine drug screen positive and self-reporting past 3-day exposure) and unknown exposure to fentanyl (i.e. urine drug screen positive and self-reporting no past three-day exposure), respectively. RESULTS: Among 590 PWID, 296 (50.2%) tested positive for fentanyl. Of those, 143 (48.3%) had suspected/known and 153 (51.7%) had unknown exposure to fentanyl. In multivariable analyses, using supervised injection sites and possessing naloxone were associated with both suspected/known and unknown exposure (all P < 0.05). Injecting drugs alone (adjusted odds ratio 3.26; 95% confidence interval: 1.72-6.16) was associated with known exposure, but not with unknown exposure. DISCUSSION AND CONCLUSIONS: We found a high prevalence of fentanyl exposure in our sample of PWID, with one half of those exposed consuming fentanyl unknowingly. While those exposed to fentanyl appeared more likely to utilise some overdose prevention services, PWID with suspected/known fentanyl exposure were more likely to inject alone, indicating a need for additional overdose prevention efforts for this group.