"Shared experience makes this all possible": documenting the guiding principles of peer-led services for people released from prison.

BACKGROUND: There is a growing body of evidence demonstrating the effectiveness of peer-led services in supporting community reintegration for people released from prison. This study aims to document the guiding principle of a peer-led service for people released from prison, from the perspective of peer mentors. METHODS: Data were collected using focus groups (N = 10; 2 groups with 5 participants each) and one-on-one interviews (N = 5) including a total of 13 people, representing all UTGSS staff at the time of the study. An inductive thematic analysis was used to identify patterns in the data. Initial coding was done by using "in-vivo" codes (i.e. applying codes to terms used by participants). This informed the direction of the next stage of analysis, which focused on identifying categories that synthesized the codes and data across transcripts. In this stage, broad themes and sub-themes were developed. FINDINGS: Six themes were constructed to reflect the guiding principles of UTGSS staff. This includes four central themes: 1) Offering hope; 2) Building respectful relationships; 3) Providing consistent support; 4) Meeting people where they are at. Two connected themes are also reported: 1) Relying on shared experience, which participants reported serves as the foundation for practicing these guiding principles and 2) Bridging connections to services, which reflects the outcome of practicing these guiding principles. CONCLUSION: The principles identified in this study can be used by UTGSS staff as a guide for checking-in on progress with clients and may be considered as a model for reflection on practice by staff providing similar peer-led services. These principles should not be applied in a prescriptive way, as relationship building is at the centre of peer support, and different applications will be required depending on clients' goals and the range of supports available within their community.

Factors associated with obtaining prescribed safer supply among people accessing harm reduction services: findings from a cross-sectional survey.

BACKGROUND: With growing rates of unregulated drug toxicity death and concerns regarding COVID-19 transmission among people who use drugs, in March 2020, prescribed safer supply guidance was released in British Columbia. This study describes demographic and substance use characteristics associated with obtaining prescribed safer supply and examines the association between last 6-month harm reduction service access and obtaining prescribed safer supply. METHODS: Data come from the 2021 Harm Reduction Client Survey administered at 17 harm reduction sites across British Columbia. The sample included all who self-reported use of opioids, stimulants, or benzodiazepines in the prior 3 days (N = 491), given active use of these drugs was a requirement for eligibility for prescribed safer supply. The dependent variable was obtaining a prescribed safer supply prescription (Yes vs. No). The primary independent variables were access to drug checking services and access to overdose prevention services in the last 6 months (Yes vs. No). Descriptive statistics (Chi-square tests) were used to compare the characteristics of people who did and did not obtain a prescribed safer supply prescription. Multivariable logistic regression models were run to examine the association of drug checking services and overdose prevention services access with obtaining prescribed safer supply. RESULTS: A small proportion (n = 81(16.5%)) of the sample obtained prescribed safer supply. After adjusting for gender, age, and urbanicity, people who reported drug checking services access in the last 6 months had 1.67 (95% CI 1.00-2.79) times the odds of obtaining prescribed safer supply compared to people who had not contacted these services, and people who reported last 6 months of overdose prevention services access had more than twice the odds (OR 2.08 (95% CI 1.20-3.60)) of prescribed safer supply access, compared to people who did not access these services. CONCLUSIONS: Overall, the proportion of respondents who received prescribed safer supply was low, suggesting that this intervention is not reaching all those in need. Harm reduction services may serve as a point of contact for referral to prescribed safer supply. Additional outreach strategies and service models are needed to improve the accessibility of harm reduction services and of prescribed safer supply in British Columbia.

Peer-led safer supply and opioid agonist treatment medication distribution: a case study from rural British Columbia.

BACKGROUND: British Columbia (BC) has been facing a public health emergency of overdose since 2016, with rural regions of the province facing the highest rates of death. Peers (in this case, people with lived experience of substance use) are known to be effective patient navigators in health systems and can play a role in connecting patients to care and reducing overdose risk. CASE PRESENTATION: We outline a peer-led program focused on opioid agonist treatment and prescribed safe supply medication delivery that began in March 2020 at a clinic in rural BC. The peer takes an Indigenous harm reduction approach and is focused on meeting the needs of the whole person. The peer has regular contact with approximately 50 clients and navigates medication delivery and appointments for approximately 10-15 people each day. Clients have been retained on the medication, and experienced improvement in other outcomes, including securing housing, employment and managing acute and chronic health conditions. The peer has established contact with clients since March 2020 to support engagement with health care and continuity of medication access. This program highlights the importance and value of peer-led work and need for further investments in peer-led programs to respond to the unregulated drug poisoning crisis. CONCLUSIONS: This peer-led intervention is a promising approach to engaging people who remain disconnected from health services in care in a rural community. This model could be adapted to other settings to support patient contact with the health system and medication access and continuity, with the ultimate goal of reducing overdose risk.

Concurrent use of opioids and stimulants and risk of fatal overdose: A cohort study.

BACKGROUND: Stimulant use has been rising among people with opioid use disorder in recent years in North America, alongside a parallel rise in illicit drug toxicity (overdose) deaths. This study aimed to examine the association between stimulant use and overdose mortality. METHODS: Data from a universal health insurance client roster were used to identify a 20% random general population sample (aged ≥12) in British Columbia, Canada between January 1 2015 and December 31 2018 (N = 1,089,682). Provincial health records were used to identify people who used opioids and/or stimulants. Fatal overdose observed during follow-up (January 12,015- December 312,018) was retrieved from Vital Statistics Death Registry and BC Coroners Service Data. Potential confounders including age, sex, health region, comorbidities and prescribed medications were retrieved from the provincial client roster and health records. RESULTS: We identified 7460 people who used stimulants and or opioids. During follow-up there were 272 fatal overdose events. People who used both opioids and stimulants had more than twice the hazard of fatal overdose (HR: 2.02, 95% CI: 1.47-2.78, p < 0.001) compared to people who used opioids only. The hazard of death increased over time among people who used both opioids and stimulants. CONCLUSIONS: There is an urgent need to prioritize the service needs of people who use stimulants to reduce overdose mortality in British Columbia. Findings have relevance more broadly in other North American settings, where similar trends in opioid and stimulant polysubstance use have been observed.

Identifying behaviours for survival and wellness among people who use methamphetamine with opioids in British Columbia: a qualitative study.

BACKGROUND: British Columbia (BC) has been in a state of public health emergency since 2016, due to the unprecedented numbers of fatal and non-fatal drug toxicity (i.e. overdose) events. Methamphetamine detection in illicit drug toxicity deaths increased from 14% in 2012 to 43% in 2020 suggesting a concerning trend of concurrent methamphetamine and opioid use in BC, consistent with rising patterns identified across North America. People who use methamphetamine concurrently with opioids face an elevated risk of harm. This study aimed to identify behaviours for survival and wellness practiced by people who concurrently use methamphetamine and opioids. METHODS: One-on-one semi-structured interviews were conducted by peer research assistants in person and by telephone. Thematic analysis was carried out to identify patterns in behaviours participants described as important to their safety in the context of concurrent use of methamphetamine and opioids. RESULTS: Participants (n = 22) were distributed across the province with at least four participants from each of the five geographic health regions: 64% self-identified as men, and 50% self-identified as Indigenous. Daily methamphetamine use was reported by 72.7% of participants, and 67.3% reported using alone either often or always. Participants made several considerations and adaptations in order to balance the perceived benefits and risks of their use of methamphetamine with opioids. Two overarching themes were identified to describe how participants adapted their use for survival and wellness. The first was personal safety behaviours which included self-regulation and self-care behaviours. The second was interpersonal safety behaviours which included using alongside peers, and engaging with peer-led services (e.g. community outreach organizations) and public health-led services (e.g. overdose prevention sites) to reduce the risk of harm. Participants identified many gaps in available services to meet their diverse needs. CONCLUSIONS: This manuscript identified diversity in participants' methamphetamine and opioid use (i.e. frequency, route of administration), and a range of behaviours that were performed to improve wellness and survival while using methamphetamine and opioids. Harm reduction and treatment responses must be robust and adaptable to respond to the diversity of patterns of substance use among people who use methamphetamine and opioids concurrently, so as to not perpetuate harm and leave people behind.

Use of sustained release dextroamphetamine for the treatment of stimulant use disorder in the setting of injectable opioid agonist treatment in Canada: a case report.

BACKGROUND: For people with opioid use disorder who are not responding to oral opioid agonist treatment, evidence supports the effectiveness of injectable opioid agonist treatment with injectable hydromorphone (an opioid analgesic) and diacetylmorphine (pharmaceutical grade heroin). While this treatment is effective at reducing illicit opioid use, concurrent cocaine use is prevalent. Dextroamphetamine (a central nervous system stimulant) has been found to be a safe and effective treatment for cocaine dependence among people receiving injectable opioid agonist treatment in Europe. We present the first report of dextroamphetamine prescribing offered for the treatment of stimulant use disorder among a patient receiving iOAT outside of a clinical trial. This case report can be used to inform clinical practice in the treatment of cocaine use disorder, an area where interventions are currently lacking. CASE PRESENTATION: Dextroamphetamine was prescribed to a 51-year-old male who was diagnosed with concurrent opioid and stimulant use disorder in an injectable opioid agonist treatment clinic in Vancouver, Canada. He reported smoking crack cocaine daily for more than two decades and was experiencing health consequences associated with this use. He presented to his routine physician visit with the goal of reducing his cocaine use and was prescribed dextroamphetamine for the treatment of stimulant use disorder. After 4-weeks the patient was tolerating the medication with no observed adverse events and was achieving his therapeutic goal of reducing his cocaine use. CONCLUSIONS: Dextroamphetamine can be prescribed to support patients with stimulant use disorder to reduce or stop their use of cocaine. The case demonstrated that when dextroamphetamine was prescribed, a significant reduction in cocaine use was experienced among a patient that had been regularly using cocaine on a daily basis for many years. Daily contact with care for the opioid medication promoted adherence to the stimulant medication and allowed for monitoring of dose and tolerance. Settings where patients are in regular contact with care such as oral and injectable opioid agonist treatment clinics serve as a suitable location to integrate dextroamphetamine prescribing for patients that use illicit stimulants to reduce use and associated harms.

The relationship between sense of community belonging and self-rated mental health among Canadians with mental or substance use disorders.

Background: One-third of Canadians meet the criteria for a mental or substance use disorder at some point in their lifetime. While prevention and treatment efforts have been focused on the individual, studies suggest the importance of incorporating social and community factors.Aims: This study investigates the relationship between community belonging and self-rated mental health among Canadians with mental or substance use disorders.Methods: The Canadian Community Health Survey-Mental Health (2012) is a nationally representative survey of Canadians aged 15 years and older (n = 25,113). The present analytic sample is comprised of respondents reporting a mental or substance use disorder in the previous 12 months (n = 2628). The relationship between community belonging and self-rated mental health is depicted with a multivariable multinomial logistic regression model.Results: Self-rated mental health was reported as follows: poor or fair (38.1%); good (33.7%); and very good or excellent (28.2%). In the multivariable multinomial model, a positive relationship was observed. Those reporting very strong compared to very weak community belonging had an increased odds of better mental health.Conclusions: Findings indicate the importance of social and community-based interventions to effectively engage and retain individuals in services for the prevention and treatment of mental and substance use disorders.

The Role of Gender in Suicidal Ideation among Long-term Opioid Users.

OBJECTIVE: This study aims to examine factors associated with suicidal ideation among people with opioid dependence and to explore whether these factors are gender-specific. METHODS: Cross-sectional data were collected among long-term opioid-dependent individuals ( n = 176; 46.0% women). Lifetime histories of suicidal ideation were measured using the Composite International Diagnostic Interview, and additional data were collected regarding sociodemographic characteristics, drug use, health, and adverse life events. Multivariable logistic regression was used to determine the relationships between these variables and suicidal ideation for the full study sample and separately for women and men to explore the potential role of gender. RESULTS: A total of 43.8% ( n = 77) of participants reported a lifetime history of suicidal ideation. Among those with suicidal ideation, 49.3% were women and the overall average age of first ideation was 19.82 years (SD, 11.66 years). Results from multivariable analyses showed that a history of depression, anxiety, and childhood emotional neglect and the number of lifetime traumatic events were significantly associated with higher odds of suicidal ideation. The gender-based analysis suggested that histories of depression and anxiety remained independently associated with lifetime suicidal ideation among women, whereas for men, childhood emotional neglect and the number of lifetime potentially traumatic events were independently associated with lifetime suicidal ideation. CONCLUSIONS: This study offers a critical first step to understanding factors associated with suicidal ideation among long-term opioid-dependent men and women and the potential importance of gender-sensitive approaches for suicidal behavior interventions. These data inform further research and clinical opportunities aiming to better respond to the psychological health needs of this population.

Factors Associated with Perceived Abuse in the Health Care System Among Long-Term Opioid Users: A Cross-Sectional Study.

BACKGROUND: Opioid-dependence is a chronic relapsing disorder. Histories of physical, sexual, and emotional abuse are prevalent among long-term opioid users. While perceived abuse in health care has been linked to histories of abuse in other populations it has not been investigated among long-term opioid users. OBJECTIVE: To determine factors associated with perceived abuse in health care among a sample of long-term opioid users. METHODS: Gender Matters in the Health of Long-Term Opioid Users (GeMa) was a descriptive cross-sectional study. Participants (n = 175) answered questions on health, drug use, treatment history, and victimization. A multivariable model of perceived abuse in health care was built using logistic regression. RESULTS: Half of participants (n = 88) reported perceived abuse in health care in lifetime with no gender differences. Histories of abuse, physical, and psychological health problems, and health care access were more prevalent among those reporting perceived abuse in health care compared to those not reporting such experiences. Multivariable analysis showed that more methadone maintenance treatment attempts in life, prescribed psychiatric medication in life, and having higher childhood emotional abuse scores were independently associated with perceived abuse in health care. Among all childhood neglect and abuse types measured, emotional abuse was the only significant predictor. CONCLUSIONS: A high prevalence of lifetime perceived abuse in health care (50%) was reported, along with extremely high childhood abuse and neglect scores. Consideration of these variables by health care and service providers is extremely important to improving patient perceptions of care, and ultimately health and treatment outcomes among opioid-dependent people.

Patient Perceptions of Prejudice and Discrimination by Health Care Providers and its Relationship with Mental Disorders: Results from the 2012 Canadian Community Health-Mental Health Survey Data.

Using data from a nationally representative survey, the Canadian Community Health Survey-Mental Health, this secondary analysis aimed to determine the prevalence of perceived prejudice by health care providers (HCPs) and its relationship with mental disorders. Respondents accessing HCPs in the prior year were asked if they experienced HCP prejudice. A hypothesis driven multivariable logistic regression analysis was conducted to determine the relationship between type of mental disorders and HCP prejudice. Among the 3006 respondents, 10.9 % perceived HCP prejudice, 62.4 % of whom reported a mental disorder. The adjusted odds of prejudice was highest for respondents with anxiety (OR 3.12; 95 % CI 1.60, 6.07), concurrent mood or anxiety and substance disorders (OR 3.08; 95 % CI 1.59, 5.95) and co-occurring mood and anxiety disorders (OR 2.89; 95 % CI 1.68, 4.97) compared to respondents without any mental disorders. These findings are timely for informing discussions regarding policies to address HCP prejudice towards people with mental disorders.

An ecological study of the correlation between COVID-19 support payments and overdose events in British Columbia, Canada.

BACKGROUND: Pandemic income support payments have been speculatively linked to an increased incidence of illicit drug poisoning (overdose). However, existing research is limited. METHODS: Collating Canadian Emergency Response Benefit (CERB) payment data with data on paramedic attended overdose and illicit drug toxicity deaths for the province of British Columbia at the Local Health Area (LHA) level, we conducted a correlation analysis to compare overdose rates before, during and after active CERB disbursement. RESULTS: There were 20,014,270 CERB-entitled weeks identified among residents of British Columbia for the duration of the pandemic response program. Approximately 52 % of all CERB entitled weeks in the study were among females and approximately 48 % were among males. Paramedic-attended overdoses increased uniformly across the pre-CERB, CERB and post-CERB periods, while illicit drug toxicity deaths sharply increased and then remained high over the period of the study. Correlation analyses between overdose and CERB-entitled weeks approached zero for both paramedic-attended overdoses and illicit drug toxicity deaths. CONCLUSIONS: These findings suggest that attributing the pandemic increase in overdose to income support payments is unfounded. Sustained levels of unacceptably high non-fatal and fatal drug poisonings that further increased at the start of the pandemic are reflective of complex pre-existing and pandemic-driven changes to overdose risk.

Motivators of and barriers to drug checking engagement in British Columbia, Canada: Findings from a cross-sectional study.

OBJECTIVE: Responding to increasing rates of illicit drug toxicity mortality in British Columbia, regional health authorities introduced various types and models of drug checking services starting in 2016. Uptake has been gradual yet consistent, but motivators and barriers of service use have not been well-described. METHODS: The British Columbia Harm Reduction Client Survey is a cross-sectional survey conducted at harm reduction sites across British Columbia. Data for the present findings were collected between March 2021 and January 2022. Participants (n = 537) were asked about their use of drug checking services and what prevented them from using available services. Responses were analyzed with descriptive statistics and multivariable logistic regression. RESULTS: Of all participants, 519 (96.6 %) answered the survey question on drug checking with 144 (27.7 %) reporting having used services within six months. Participants highlighted barriers such as not knowing where to access services (21.0 %), or not having services in their area (10.0 %). Among people who did not report recent use of fentanyl, 49.6 % stated they would not use their drugs if they tested positive for fentanyl. Other harm reduction behaviors were positively associated with drug checking, such as use of overdose prevention sites (adjusted odds ratio [AOR]: 2.75, 95 % confidence interval [CI]: 1.65, 4.59) and having a naloxone kit (AOR: 2.67, 95 %CI: 1.14, 6.28). Receipt of opioid agonist therapy in the previous six months was also positively associated with drug checking (AOR: 1.72, 95 %CI: 1.05, 2.83). DISCUSSION: Drug checking uptake remains low in British Columbia, however this study identified desire for services among participants, suggesting a need for expanded drug checking services. Behavioral change was reported among a high proportion of people who said they would not use their drugs if they tested positive for fentanyl, meaning that immunoassay strips alone have utility in the context of a pervasive fentanyl supply.

Effect of Risk Mitigation Guidance opioid and stimulant dispensations on mortality and acute care visits during dual public health emergencies: retrospective cohort study.

OBJECTIVE: To determine the effect of opioid and stimulant Risk Mitigation Guidance (RMG) dispensations on mortality and acute care visits during the dual public health emergencies of overdose and covid-19. DESIGN: Population based retrospective cohort study. SETTING: British Columbia, Canada. PARTICIPANTS: 5882 people with opioid or stimulant use disorder who received RMG prescriptions for opioids (n=5356) and/or stimulants (n=1061) (535 received both) from 27 March 2020 to 31 August 2021. MAIN OUTCOME MEASURES: All cause and overdose specific mortality and acute care visits in the week after RMG opioid or stimulant dispensation. RMG recipients were matched 1:1 with controls through use of high dimensional propensity score matching. Marginal structural models, executed on weekly time steps, were used to measure the effect of dispensations on outcomes. RESULTS: RMG opioid dispensations of one day or more were associated with reduced all cause mortality (adjusted hazard ratio 0.39, 95% confidence interval 0.25 to 0.60) and overdose related mortality (0.45, 0.27 to 0.75) in the subsequent week. Dispensations of RMG stimulants (≥1 days) were not significantly associated with reduced all cause mortality (adjusted hazard ratio 0.50, 0.20 to 1.23) or overdose related mortality (0.53, 0.18 to 1.56). The protective effect of RMG opioid dispensations increased with the number of days the medications were dispensed in a given week. People who received four or more days of RMG opioid dispensations had reduced all cause mortality (adjusted hazard ratio 0.09, 0.04 to 0.21) and overdose related mortality (0.11, 0.04 to 0.32) compared with the control group. Opioid RMG dispensations did not significantly modify the odds of all cause or overdose related acute care visits. Dispensations of RMG stimulants were associated with a significant decrease in the odds of acute care visits for any cause but did not affect the odds of overdose related acute care visits. CONCLUSIONS: RMG opioid dispensations were associated with reduced overdose related and all cause mortality among a sample of people with opioid use disorder. Pharmaceutical alternatives to the illegal drug supply are promising interventions to reduce mortality in people with opioid use disorder.

Opioid Coprescription Through Risk Mitigation Guidance and Opioid Agonist Treatment Receipt.

Importance: At the onset of the COVID-19 pandemic, the government of British Columbia, Canada, released clinical guidance to support physicians and nurse practitioners in prescribing pharmaceutical alternatives to the toxic drug supply. These alternatives included opioids and other medications under the risk mitigation guidance (RMG), a limited form of prescribed safer supply, designed to reduce the risk of SARS-CoV-2 infection and harms associated with illicit drug use. Many clinicians chose to coprescribe opioid medications under RMG alongside opioid agonist treatment (OAT). Objective: To examine whether prescription of hydromorphone tablets or sustained-release oral morphine (opioid RMG) and OAT coprescription compared with OAT alone is associated with subsequent OAT receipt. Design, Setting, and Participants: This population-based, retrospective cohort study was conducted from March 27, 2020, to August 31, 2021, included individuals from 10 linked health administrative databases from British Columbia, Canada. Individuals who were receiving OAT at opioid RMG initiation and individuals who were receiving OAT and eligible but unexposed to opioid RMG were propensity score matched at opioid RMG initiation on sociodemographic and clinical variables. Data were analyzed between January 2023 and February 2024. Exposure: Opioid RMG receipt (≥4 days, 1-3 days, or 0 days of opioid RMG dispensed) in a given week. Main Outcome and Measures: The main outcome was OAT receipt, defined as at least 1 dispensed dose of OAT in the subsequent week. A marginal structural modeling approach was used to control for potential time-varying confounding. Results: A total of 4636 individuals (2955 [64%] male; median age, 38 [31-47] years after matching) were receiving OAT at the time of first opioid RMG dispensation (2281 receiving ongoing OAT and 2352 initiating RMG and OAT concurrently). Opioid RMG receipt of 1 to 3 days in a given week increased the probability of OAT receipt by 27% in the subsequent week (adjusted risk ratio, 1.27; 95% CI, 1.25-1.30), whereas receipt of opioid RMG for 4 days or more resulted in a 46% increase in the probability of OAT receipt in the subsequent week (adjusted risk ratio, 1.46; 95% CI, 1.43-1.49) compared with those not receiving opioid RMG. The biological gradient was robust to different exposure classifications, and the association was stronger among those initiating opioid RMG and OAT concurrently. Conclusions and Relevance: This cohort study, which acknowledged the intermittent use of both medications, demonstrated that individuals who were coprescribed opioid RMG had higher adjusted probability of continued OAT receipt or reengagement compared with those not receiving opioid RMG.

Measuring the preferences of injectable opioid agonist treatment (iOAT) clients: Development of a person-centered scale (best-worst scaling).

BACKGROUND: Injectable opioid agonist treatment (iOAT) is effective for opioid use disorder (OUD), yet little is known about client preferences for accessing iOAT (e.g., with diacetylmorphine, hydromorphone, buprenorphine, fentanyl, etc.). Best-worst scaling (BWS) is a preference elicitation method from health economics that has never been applied to addiction care broadly, or iOAT specifically. We describe the stages of developing a BWS scale that assesses iOAT clients' treatment delivery preferences to inform program planning and maximize healthcare efficiency. METHODS: We underwent several steps to reveal the relevant attributes/levels and design the scale structure. An initial list of potential attributes and levels was established from a literature review and prior qualitative data. Then, we conducted semi-structured interviews and focus groups with clients (n=21) on their iOAT preferences to confirm the attributes and prioritize/include new ones. Next, we conducted semi-structured interviews and focus groups with iOAT experts and stakeholders to receive their input on the draft list of attributes and levels. A BWS profile case design was piloted with iOAT clients (n=18) from different sites during a think aloud interview. After several rounds of revisions, the final version was tested by iOAT clients (n=2) before the scale was launched. RESULTS: We developed a person-centered scale that assesses current and former iOAT clients' most and least wanted aspects of iOAT delivery. The final version yielded 7 unique attributes: choice of medication, choice of dose, convenience, location & space, scheduling & routines, staff & training, and types of services offered. CONCLUSION: This scale can help expand iOAT programs in a way that is person-centered, rapid, and affordable. The methodology is a guide for other regions with similar populations who aim to develop strong quantitative methodologies that prioritize client collaboration.

Drug overdose and the risk of cardiovascular diseases: a nested case-control study.

BACKGROUND: North America has been experiencing an unprecedented epidemic of drug overdose. This study investigated the associations of drug overdose with the risk of cardiovascular disease (CVD) and 11 major CVD subtypes. METHODS: This nested case-control study was based on a cohort of 20% random sample of residents in British Columbia, Canada, who were aged 18-80 years and did not have known CVD at baseline (n = 617,863). During a 4-year follow-up period, persons who developed incident CVD were identified as case subjects, and the onset date of CVD was defined as the index date. For each case subject, we used incidence density sampling to randomly select up to five control subjects from the cohort members who were alive and did not have known CVD by the index date, were admitted to an emergency department or hospital on the index date for non-CVD causes, and were matched on age, sex, and region of residence. Overdose exposure on the index date and each of the previous 5 days was examined for each subject. RESULTS: This study included 16,113 CVD case subjects (mean age 53 years, 59% male) and 66,875 control subjects. After adjusting for covariates, overdose that occurred on the index date was strongly associated with CVD [odds ratio (OR), 2.9; 95% confidence interval (CI), 2.4-3.5], especially for arrhythmia (OR, 8.6; 95% CI, 6.2-12.0), ischemic stroke (OR, 5.3; 95% CI, 2.0-14.1), hemorrhagic stroke (OR, 3.1; 95% CI, 1.2-8.3), and myocardial infarction (OR, 3.0; 95% CI, 1.5-5.8). The CVD risk was decreased but remained significantly elevated for overdose that occurred on the previous day, and was not observed for overdose that occurred on each of the previous 2-5 days. CONCLUSIONS: Drug overdose appears to be associated with increased risk of cardiovascular diseases.