Thomas Kerr's research while affiliated with University of British Columbia - Okanagan and other places

Publications (774)

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Background: OxyContin was delisted from Canadian provincial drug formularies in March 2012 and replaced with a reformulated tamper-resistant form of oxycodone (i.e., OxyNeo). We assessed if delisting of OxyContin was associated with changes in the use of unregulated opioids and other substances among people who use opioids (PWUO). Methods: Data w...
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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 soug...
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Background Substance use management in hospitals can be challenging. In response, a Canadian hospital opened an overdose prevention site (OPS) where community members and hospital inpatients can inject pre-obtained illicit drugs under supervision. This study aims to: (1) describe program utilization patterns; (2) characterize OPS visits; and (3) ev...
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Street-involved youth who use drugs (YWUD) face an elevated risk of HIV acquisition and represent a key population for HIV prevention initiatives, including pre-exposure prophylaxis (PrEP). However, little is known regarding the acceptability and feasibility of PrEP uptake and adherence among this multiply-marginalized population. Semi-structured q...
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Introduction: While substance use contributes to a substantial burden of disease, access to evidence-based harm reduction interventions remains limited or inaccessible. Preliminary research suggests that some individuals use cannabis to reduce the harms associated with their use of other substances, including opioids and stimulants. This study exam...
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Background When the novel coronavirus pandemic emerged in March 2020, many settings across Canada and the USA were already contending with an existing crisis of drug overdoses due to the toxic unregulated drug supply. In response, the Canadian province of British Columbia (BC) released innovative risk mitigation prescribing (RMP) guidelines for med...
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Background A mounting body of evidence suggests that polysubstance use (PSU) is common among people who use opioids (PWUO). Measuring PSU, however, is statistically and methodologically challenging. Person-centered analytical approaches (e.g., latent class analysis) provide a holistic understanding of individuals’ substance use patterns and help un...
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Objectives. To identify key gaps in overdose prevention interventions for mothers who use drugs and the paradoxical impact of institutional practices that can increase overdose risk in the context of punitive drug policies and a toxic drug supply. Methods. Semistructured interviews were conducted with 40 women accessing 2 women-only, low-barrier su...
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Objectives. To identify key gaps in overdose prevention interventions for mothers who use drugs and the paradoxical impact of institutional practices that can increase overdose risk in the context of punitive drug policies and a toxic drug supply. Methods. Semi-structured interviews were conducted with 40 women accessing 2 women-only, low-barrier...
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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 ad...
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Background and Aims In response to a dramatic rise in overdose deaths due to injection drug use, there was a rapid scale-up of low-threshold supervised injection services (SIS), termed ‘overdose prevention sites’ (OPS), in Vancouver, Canada in December 2016. We measured the potential impact of this intervention on SIS use and related health outcome...
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Background: While patient-reported treatment dissatisfaction is considered an important factor in determining the success of substance use disorder treatment, the levels of dissatisfaction with opioid agonist therapies (OAT) and its relationship with the risk of fentanyl exposure have not been characterized in the context of the ongoing opioid ove...
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Background: Methadone maintenance treatment (MMT) is an effective treatment for opioid use disorder. However, subtherapeutic dosing may lead to continued opioid use by failing to suppress opioid withdrawal and craving. Preclinical and pilot experimental research suggests that cannabinoids may reduce opioid withdrawal and craving. We sought to test...
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Objective The emergence of synthetic fentanyl has been a main contributor to North America's rising overdose death rates. While increasing attention has been given to drug-related harm among youth, little is known about how social-structural conditions influence their risk of fentanyl exposure. Therefore, we evaluated potential relationships betwee...
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Objectives: In Canada, and elsewhere, Indigenous people who use illicit drugs and/or alcohol (WUID/A) experience a disproportionate burden of HIV-related harm. This study examined HIV risk perceptions and behaviours among Indigenous people WUID/A living in the Downtown Eastside (DTES) and the policies and practices that shape inequities and vulnera...
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Background Although non-medical use of pharmaceutical opioids (POs) is associated with a number of risks, in the context of the opioid-overdose crisis, it may have the secondary benefit of decreasing the risk of exposure to more potent opioids from unregulated sources. The aim of this study was to assess the effects of using diverted POs on fentany...
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Background People who use drugs (PWUD) are known to fear calling emergency medical services (EMS) for drug overdoses. In response, drug-related Good Samaritan Laws (GSLs) have been widely adopted in the USA and Canada to encourage bystanders to call emergency medical services (EMS) in the event of a drug overdose. However, the effect of GSLs on EMS...
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Background In light of the ongoing opioid overdose crisis, there is an urgent need for research on the impacts of mental health among people presenting with concurrent pain and substance use. This study examined the effect of depressive symptoms on pain severity and functional interference among people who use drugs (PWUD) during a community-wide o...
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Background Violent victimization is common among people who use illegal drugs (PWUD) and is a source of significant health-related harm. However, little attention has been paid to how antecedent childhood trauma among PWUD may contribute to the risk of victimization in adulthood. Objective This study sought to examine the relationship between chil...
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Background: Despite increasing prevalence of illicit fentanyl use in the US and Canada, preference for fentanyl over other illicit opioids has not been fully characterized. Therefore, we sought to describe changes in illicit opioid preferences over time among people who inject drugs (PWID). Methods: Data were obtained from two prospective cohort st...
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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 po...
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Background: The efficacy of methadone in reducing morbidity and mortality associated with opioid use disorder is supported by a wealth of evidence, yet methadone retention is often poor. While crystal methamphetamine (methamphetamine) use has been recently increasing in many countries, the effect of frequency of methamphetamine use on methadone di...
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Although public injecting has been studied in large urban centres, little is known about the factors that drive public injecting in remote communities. This study sought to explore public and semi-public injection in Thunder Bay, a remote and mid-sized city in Northwestern Ontario. Peer researchers completed surveys with people who inject drugs. Mu...
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Background There is concern that cannabis use negatively affects vulnerable groups such as youth; however, the relationship between cannabis use and health care utilization has not been well characterized in this population. We longitudinally evaluated the association between daily cannabis use and hospitalization among a prospective cohort of stre...
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The practice of prescription opioid (PO) diversion remains highly controversial and has been characterized as a source of significant drug-related harm by physicians and public health officials. We critically analyze the “problem” of diversion through an examination of the perspectives of people who divert POs during an overdose epidemic to better...
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Background While exposure to traumatic events and subsequent post-traumatic stress disorder (PTSD) are common among people who use drugs (PWUD), little is known about gender-based differences associated with PTSD in this population. We explore gender-based differences in factors associated with a probable PTSD diagnosis in a cohort of PWUD from Van...
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Background The synchronised monthly disbursement of income assistance, whereby all recipients are paid on the same day, has been associated with increases in illicit drug use and serious associated harms. This phenomenon is often referred to as the cheque effect. Because payment variability can affect consumption patterns, this study aimed to asses...
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Objective Prescription opioid (PO) diversion is widely regarded as a driver of overdose mortality. However, less is known about the rationale for using diverted POs during an overdose epidemic and how contextual factors (e.g., poverty, drug policies) may affect this practice. Therefore, we sought to examine this phenomenon. Method We conducted qua...
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Background Across the United States and Canada drug-related Good Samaritan laws (GSLs) have been enacted to encourage observers of acute drug overdose events to contact emergency medical services (EMS) without fear of legal repercussions. However, little is known about the working knowledge of GSLs among people who use illicit drugs (PWUD). We soug...
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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 p...
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Introduction: Illicit drug use while admitted to hospital is common amongst people who use drugs. Furthermore, non-medical prescription opioid use (NMPOU) is increasingly being used by this population. This study was undertaken to investigate the relationship between NMPOU and having ever reported using illicit drugs in the hospital. Methods: Th...
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Overdose response programs in North America increasingly employ task shifting—shifting overdose response tasks to less specialized workers—to increase effectiveness and promote involvement of people with lived/living experience of drug use (PWLE). In Canada, task shifting has occurred through community-driven implementation of overdose response pro...
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Introduction Retention in opioid agonist therapy consistently has been linked with improved outcomes among people with opioid use disorder. However, less is known about the links between patterns of engagement in opioid agonist therapy over the long term and overdose risk. This study assesses the association of opioid agonist therapy retention traj...
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Introduction Drug sellers are often represented as morally bereft actors and as being, in part, responsible for North America's overdose crisis. In Canada and the United States, drug sellers selling fentanyl and fentanyl-adulterated drugs have been charged with manslaughter when their clients fatally overdose, representing a retrenchment of drug wa...
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Background The United States and Canada are amidst an opioid overdose crisis, with the Canadian province of British Columbia (BC) among the hardest hit. In response, drug checking services (DCS) have been introduced in this setting as a novel pilot harm reduction intervention though little is known about usage rates. Therefore, we sought to identif...
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Background People who require help injecting illicit drugs experience elevated rates of a range of health-related harms, including overdose and acquisition of blood-borne pathogens. In response, some supervised injection services (SIS) in Canada have begun to permit clients to be physically injected by fellow clients or staff members. However, litt...
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Background North America remains in the midst of an escalating opioid overdose epidemic, largely driven by the influx of synthetic opioids such a fentanyl and related analogues. High rates of mental illness among substance-using populations have been well documented; in particular, opioid-using individuals suffer from high rates of PTSD. Despite th...
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Background The ongoing opioid overdose crisis is driven largely by exposure to illicitly-manufactured fentanyl. Preliminary observational and experimental research suggests that cannabis could potentially play a role in reducing use of prescription opioids among individuals with chronic pain. However, there is limited data on the effects of cannabi...
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Background The opioid overdose crisis underscores the need for health services among people who use drugs (PWUD) with concurrent pain. Aims Investigating the effect of pain on barriers to accessing health services among PWUD. Design Prospective cohort study. Settings A setting of universal access to no-cost medical care in Vancouver, Canada from...
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Background Youth aging-out of the child welfare system (CWS) experience numerous vulnerabilities including, elevated rates of substance use and substance use disorders. Calls to improve services to transition youth to independence are common; however, evidence of the long-term impacts associated with transitional service utilization is scarce. Furt...
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North America is experiencing an overdose crisis driven by fentanyl, related analogues, and fentanyl-adulterated drugs. In response, there have been increased calls for “safe supply” interventions based on the premise that providing a safer alternative (i.e., pharmaceutical drugs of known quality/quantity, non-adulterated, with user agency in consu...
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Aim: Given that co-occurring pain is prevalent among people who use drugs (PWUD), we sought to explore the effect of pain severity on accessing addiction treatment. Methods: Data were derived from two prospective cohort studies of PWUD in Vancouver, Canada from June 2014 to May 2016. Multivariable generalized linear mixed-effects multiple regres...
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Background: Within the context of the ongoing overdose crisis and limitations of conventional opioid treatments, the scale-up of injectable hydromorphone (HDM) and diacetylmorphine (DAM) as evidenced-based treatments is currently underway in some settings in Canada. Past research has underscored the importance of treatment initiation in shaping on...
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Background: Opioid agonist therapy (OAT) models are generally provided without consideration of how pre-treatment characteristics may be associated with outcome. Therefore, we aimed to first characterize longitudinal trajectories of opioid use before initiating OAT. Then we explored the impact of OAT on opioid use across these pre-treatment trajec...
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Background: North America is experiencing an overdose crisis driven by illicitly-manufactured fentanyl, related analogues, and fentanyl-adulterated drugs. The concept of 'safe supply' has been suggested as a potential measure to address the overdose crisis by providing a regulated alternative to illicit opioids to people at high risk of fatal over...
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Background The United States and Canada are in the midst of an overdose epidemic, fueled by illicitly manufactured fentanyl. While marked differences in vulnerability to drug-related harm between men and women who use drugs is well characterized, the extent to which gender differences manifest in the present overdose crisis remains understudied. We...
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Evidence-based medicine has consistently prized the epistemological value of randomized-controlled trials (RCTs) owing to their methodological advantages over alternative designs such as observational studies. However, there are limitations to RCTs that hinder their ability to study chronic and dynamic conditions such as substance use and addiction...
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Objectives. To evaluate the impact of frequent cannabis use on injection cessation and injection relapse among people who inject drugs (PWID). Methods. Three prospective cohorts of PWID from Vancouver, Canada, provided the data for these analyses. We used extended Cox regression analysis with time-updated covariates to analyze the association betwe...
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Background With the emergence of illicitly-manufactured fentanyl, drug overdose deaths have risen in unprecedented numbers. In this context, there is an urgent need to characterize potential changes in drug use behaviors among people who use drugs (PWUD). Objective To examine changes in drug use behaviors following the emergence of illicit fentany...
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Sharing used syringes is an important route of HIV transmission, however, factors shaping used syringe-lending among antiretroviral therapy (ART)-naïve HIV-positive people who inject drugs (PWID) are not well-characterized. Multivariable logistic regression analyses using generalized estimating equations (GEE) were employed to investigate correlate...
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Background and Aims Income assistance is critical to the health and well‐being of socioeconomically marginalized people who use illicit drugs (PWUD). However, past literature paradoxically identifies unintended increases in drug‐related harm coinciding with synchronized payments that may magnify signals for drug use. The scope of such harm has not...
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Introduction Methamphetamine use is increasing in North America and is associated with numerous negative health effects and social harms. As drug‐related harms are often gendered, this study sought to examine the differential impacts of gender on the trends, risk factors and health implications of crystal methamphetamine use among a Canadian cohort...
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Background: A primary response to the alarming rise in overdose and mortality due to nonmedical prescription opioid (PO) use has been to restrict opioid prescribing; however, little is known about the relationship between obtaining opioids from a physician and overdose risk among people who use POs nonmedically and illicit street drugs. Objectives...
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Background Cannabis use is common among marginalized people who use illicit drugs (PWUD) but reasons for use remain poorly investigated. We sought to explore how different intentions for cannabis use relate to social, structural, and behavioural factors among PWUD in Vancouver, Canada. Methods We used data from cannabis-using participants in two c...
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The ongoing overdose crisis in the United States and Canada has highlighted the urgent need for innovative interventions to reduce drug-related harms. This, in turn, has led to increased interest in the potential of cannabis as a harm reduction strategy. While Canada has recently legalized cannabis, meaningful barriers to accessing legal cannabis r...
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Background and Aims: Little is known about how the expansion of opioid agonist therapy (OAT) and emergence of fentanyl in the illicit drug supply in North America has influenced non-fatal opioid overdose (NFOD) risk. Therefore, we sought to identify patterns of substance use and addiction treatment engagement (i.e., OAT, other inpatient or outpatie...
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“The Molson” is a low-barrier, peer-staffed, supervised consumption site located in Vancouver, Canada. In addition to overdose response, this site offers drug checking and a colocated injectable hydromorphone treatment program, and it distributes tablet and liquid hydromorphone to service users at high risk of overdose. Our evaluation suggests bene...
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Background Attention to how women are differentially impacted within harm reduction environments is salient amidst North America's overdose crisis. Harm reduction interventions are typically ‘gender-neutral’, thus failing to address the systemic and everyday racialized and gendered discrimination, stigma, and violence extending into service setting...
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Background: Supervised injection facilities (SIFs) have been established in many settings, in part to reduce risks associated with injecting in public, including exposure to violence. However, the relationship between SIF use and experiencing violence has not yet been thoroughly evaluated. We sought to longitudinally examine the gender-specific rel...
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Background Although previous studies have shown that opioid agonist therapy (OAT) is linked to reductions in illicit opioid use, less is known about how OAT impacts the use of other psychoactive substances. We aimed to examine the changes in use of different substances by comparing patterns before and after initiating OAT. Methods Data for this st...
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Objective: High levels of chronic pain interference with daily activities are known to negatively impact quality of life. Although mental health conditions have been associated with pain interference and child abuse, research has been mixed regarding it acting as a mediator, with even less known among people who inject drugs. Therefore, we sought...
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Objectives: In Canada, and elsewhere, indigenous peoples who use illicit drugs and/or alcohol (IPWUID/A) commonly experience vulnerability and a disproportionate burden of harm related to substance use. In Vancouver, Canada, there are concerns that inequitable access, retention, and post treatment care within substance use treatment programs may e...
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Background: Long-term engagement in opioid agonist therapy (OAT) has been consistently associated with reduced risk for morbidity and mortality in people with opioid use disorder (OUD). However, the dynamic nature of engagement/disengagement in OUD care for over time is poorly captured by traditional metrics. We characterized long-term longitudina...
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Background: Since 2013, fentanyl-contaminated drugs have been driving North America’s opioid-overdose epidemic. Drug checking, which enables people who use illicit drugs (PWUD) to test and receive feedback regarding the contents of their drugs, is being considered as a potential tool to address the toxic drug supply. While some PWUD witness overdos...
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Background. Heterogeneity in HIV microepidemics across US cities necessitates locally oriented, combination implementation strategies to prioritize resources. We calibrated and validated a dynamic, compartmental HIV transmission model to establish a status quo treatment scenario, holding constant current levels of care for 6 US cities. Methods. Bui...
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We examined factors associated with reporting sex with men among men who inject drugs in Vancouver, Canada. Data were drawn from three open prospective cohorts of people who use drugs between 2005 and 2014. Generalized estimating equations were used to identify factors associated with reporting non-transactional sex with men (MSM) in the previous 6...
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The objective of this study was to qualitatively explore how queer women sex workers’ experiences of stigma impacted health and housing access in Vancouver, Canada. In-depth semi-structured interviews were conducted with 56 queer women sex workers in Vancouver, Canada between June 2012 and May 2013. Participants described sexual stigma in the form...
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Background People who inject drugs (PWID) experience elevated rates of premature mortality. Although previous studies have demonstrated the role of supervised injection facilities (SIFs) in reducing various harms associated with injection drug use, including accidental overdose death, the possible impact of SIF use on all-cause mortality is unknown...
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Background Ecological research suggests that increased access to cannabis may facilitate reductions in opioid use and harms, and medical cannabis patients describe the substitution of opioids with cannabis for pain management. However, there is a lack of research using individual-level data to explore this question. We aimed to investigate the long...
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Background: Urban drug scenes are characterized by high prevalence of illicit drug dealing and use, violence and poverty, much of which is driven by the criminalization of people who use illicit drugs (PWUD) and the associated stigma. Despite significant public health needs, little is understood about patterns of moving into urban drug scenes amon...