The Ontario Integrated Supervised Injection Services Cohort Study of People Who Inject Drugs in Toronto, Canada (OiSIS-Toronto): Cohort Profile

An individual-based dynamic model to assess interventions to mitigate opioid overdose risk

BACKGROUND

Illicit opioid overdose continues to rise in North America and is a leading cause of death. Mathematical modeling is a valuable tool to investigate the epidemiology of this public health issue, as it can characterize key features of population outcomes and quantify the broader effect of structural and interventional changes on overdose mortality. The aim of this study is to quantify and predict the impact of key harm reduction strategies at differing levels of scale-up on fatal and nonfatal overdose among a population of people engaging in unregulated opioid use in Toronto.

METHODS

An individual-based model for opioid overdose was built featuring demographic and behavioural variation among members of the population. Key individual attributes known to scale the risk of fatal and nonfatal overdose were identified and incorporated into a dynamic modeling framework, wherein every member of the simulated population encompasses a set of distinct characteristics that govern demographics, intervention usage, and overdose incidence. The model was parametrized to fatal and nonfatal overdose events reported in Toronto in 2019. The interventions considered were opioid agonist therapy (OAT), supervised consumption sites (SCS), take-home naloxone (THN), drug-checking, and reducing fentanyl in the drug supply. Harm reduction scenarios were explored relative to a baseline model to examine the impact of each intervention being scaled from 0% use to 100% use on overdose events.

RESULTS

Model simulations resulted in 3690.6 nonfatal and 295.4 fatal overdoses, coinciding with 2019 data from Toronto. From this baseline, at full scale-up, 290 deaths were averted by THN, 248 from eliminating fentanyl from the drug supply, 124 from SCS use, 173 from OAT, and 100 by drug-checking services. Drug-checking and reducing fentanyl in the drug supply were the only harm reduction strategies that reduced the number of nonfatal overdoses.

CONCLUSIONS

Within a multi-faceted harm reduction approach, scaling up take-home naloxone, and reducing fentanyl in the drug supply led to the largest reduction in opioid overdose fatality in Toronto. Detailed model simulation studies provide an additional tool to assess and inform public health policy on harm reduction.

Economic evaluation of the effect of needle and syringe programs on skin, soft tissue, and vascular infections in people who inject drugs: a microsimulation modelling approach

BACKGROUND

Needle and syringe programs (NSP) are effective harm-reduction strategies against HIV and hepatitis C. Although skin, soft tissue, and vascular infections (SSTVI) are the most common morbidities in people who inject drugs (PWID), the extent to which NSP are clinically and cost-effective in relation to SSTVI in PWID remains unclear. The objective of this study was to model the clinical- and cost-effectiveness of NSP with respect to treatment of SSTVI in PWID.

METHODS

We performed a model-based, economic evaluation comparing a scenario with NSP to a scenario without NSP. We developed a microsimulation model to generate two cohorts of 100,000 individuals corresponding to each NSP scenario and estimated quality-adjusted life-years (QALY) and cost (in 2022 Canadian dollars) over a 5-year time horizon (1.5% per annum for costs and outcomes). To assess the clinical effectiveness of NSP, we conducted survival analysis that accounted for the recurrent use of health care services for treating SSTVI and SSTVI mortality in the presence of competing risks.

RESULTS

The incremental cost-effectiveness ratio associated with NSP was $70,278 per QALY, with incremental cost and QALY gains corresponding to $1207 and 0.017 QALY, respectively. Under the scenario with NSP, there were 788 fewer SSTVI deaths per 100,000 PWID, corresponding to 24% lower relative hazard of mortality from SSTVI (hazard ratio [HR] = 0.76; 95% confidence interval [CI] = 0.72-0.80). Health service utilization over the 5-year period remained lower under the scenario with NSP (outpatient: 66,511 vs. 86,879; emergency department: 9920 vs. 12,922; inpatient: 4282 vs. 5596). Relatedly, having NSP was associated with a modest reduction in the relative hazard of recurrent outpatient visits (HR = 0.96; 95% CI = 0.95-0.97) for purulent SSTVI as well as outpatient (HR = 0.88; 95% CI = 0.87-0.88) and emergency department visits (HR = 0.98; 95% CI = 0.97-0.99) for non-purulent SSTVI.

CONCLUSIONS

Both the individuals and the healthcare system benefit from NSP through lower risk of SSTVI mortality and prevention of recurrent outpatient and emergency department visits to treat SSTVI. The microsimulation framework provides insights into clinical and economic implications of NSP, which can serve as valuable evidence that can aid decision-making in expansion of NSP services.

Validation of case-ascertainment algorithms using health administrative data to identify people who inject drugs in Ontario, Canada

OBJECTIVES

Health administrative data can be used to improve the health of people who inject drugs by informing public health surveillance and program planning, monitoring, and evaluation. However, methodological gaps in the use of these data persist due to challenges in accurately identifying injection drug use (IDU) at the population level. In this study, we validated case-ascertainment algorithms for identifying people who inject drugs using health administrative data in Ontario, Canada.

STUDY DESIGN AND SETTING

Data from cohorts of people with recent (past 12 months) IDU, including those participating in community-based research studies or seeking drug treatment, were linked to health administrative data in Ontario from 1992 to 2020. We assessed the validity of algorithms to identify IDU over varying look-back periods (ie, all years of data [1992 onwards] or within the past 1-5 years), including inpatient and outpatient physician billing claims for drug use, emergency department (ED) visits or hospitalizations for drug use or injection-related infections, and opioid agonist treatment (OAT).

RESULTS

Algorithms were validated using data from 15,241 people with recent IDU (918 in community cohorts and 14,323 seeking drug treatment). An algorithm consisting of ≥1 physician visit, ED visit, or hospitalization for drug use, or OAT record could effectively identify IDU history (91.6% sensitivity and 94.2% specificity) and recent IDU (using 3-year look back: 80.4% sensitivity, 99% specificity) among community cohorts. Algorithms were generally more sensitive among people who inject drugs seeking drug treatment.

CONCLUSION

Validated algorithms using health administrative data performed well in identifying people who inject drugs. Despite their high sensitivity and specificity, the positive predictive value of these algorithms will vary depending on the underlying prevalence of IDU in the population in which they are applied.

The impact of the COVID-19 pandemic on people who use drugs in three Canadian cities: a cross-sectional analysis

BACKGROUND

The COVID-19 pandemic had a disproportionate impact on the health and wellbeing of people who use drugs (PWUD) in Canada. However less is known about jurisdictional commonalities and differences in COVID-19 exposure and impacts of pandemic-related restrictions on competing health and social risks among PWUD living in large urban centres.

METHODS

Between May 2020 and March 2021, leveraging infrastructure from ongoing cohorts of PWUD, we surveyed 1,025 participants from Vancouver (n = 640), Toronto (n = 158), and Montreal (n = 227), Canada to describe the impacts of pandemic-related restrictions on basic, health, and harm reduction needs.

RESULTS

Among participants, awareness of COVID-19 protective measures was high; however, between 10 and 24% of participants in each city-specific sample reported being unable to self-isolate. Overall, 3-19% of participants reported experiencing homelessness after the onset of the pandemic, while 20-41% reported that they went hungry more often than usual. Furthermore, 8-33% of participants reported experiencing an overdose during the pandemic, though most indicated no change in overdose frequency compared the pre-pandemic period. Most participants receiving opioid agonist therapy in the past six months reported treatment continuity during the pandemic (87-93%), however, 32% and 22% of participants in Toronto and Montreal reported missing doses due to service disruptions. There were some reports of difficulty accessing supervised consumption sites in all three sites, and drug checking services in Vancouver.

CONCLUSION

Findings suggest PWUD in Canada experienced difficulties meeting essential needs and accessing some harm reduction services during the COVID-19 pandemic. These findings can inform preparedness planning for future public health emergencies.

Overdose mortality incidence and supervised consumption services in Toronto, Canada: an ecological study and spatial analysis

BACKGROUND

Supervised consumption services (SCS) prevent overdose deaths onsite; however, less is known about their effect on population-level overdose mortality. We aimed to characterise overdose mortality in Toronto, ON, Canada, and to establish the spatial association between SCS locations and overdose mortality events.

METHODS

For this ecological study and spatial analysis, we compared crude overdose mortality rates before and after the implementation of nine SCS in Toronto in 2017. Data were obtained from the Office of the Chief Coroner of Ontario on cases of accidental death within the City of Toronto for which the cause of death involved the use of an opiate, synthetic or semi-synthetic opioid, or other psychoactive substance. We assessed overdose incident data for global spatial autocorrelation and local clustering, then used geographically weighted regression to model the association between SCS proximity and overdose mortality incidence in 2018 and 2019.

FINDINGS

We included 787 overdose mortality events in Toronto between May 1, 2017, and Dec 31, 2019. The overdose mortality rate decreased significantly in neighbourhoods that implemented SCS (8·10 deaths per 100 000 people for May 1-July 31, 2017, vs 2·70 deaths per 100 000 people for May 1-July 31, 2019; p=0·037), but not in other neighbourhoods. In a geographically weighted regression analysis that adjusted for the availability of substance-use-related services and overdose-related sociodemographic factors by neighbourhood, the strongest local regression coefficients of the association between SCS and overdose mortality location ranged from -0·60 to -0·64 per mile in 2018 and from -1·68 to -1·96 per mile in 2019, suggesting an inverse association.

INTERPRETATION

We found that the period during which SCS were implemented in Toronto was associated with a reduced overdose mortality in surrounding neighbourhoods. The magnitude of this inverse association increased from 2018 to 2019, equalling approximately two overdose fatalities per 100 000 people averted in the square mile surrounding SCS in 2019. Policy makers should consider implementing and sustaining SCS across neighbourhoods where overdose mortality is high.

FUNDING

The Canadian Institutes of Health Research.

The multiple makings of a supervised consumption service in a hospital setting

BACKGROUND

Whereas supervised consumption services (SCSs) are common in many community settings, they are seldomly found in acute care hospitals. As hospitals present unique circumstances that can shape the impacts of an SCS, careful consideration of local implementation contexts and practices is required. We explored the pre-implementation stage of an SCS, to examine how an SCS is made and made differently in relation to the material-discursive context of the hospital.

METHODS

We conducted 11 focus groups with 83 staff and clinicians at an inner-city hospital in Toronto, Canada. Data analysis followed principles of grounded theory and was informed by an 'evidence making interventions' framework.

RESULTS

While most participants indicated they would support the establishment of an SCS at the hospital, multiple enactments of an SCS emerged. An SCS was enacted: as a means to reduce drug-related risks for all people who use drugs, as an opportunity to intervene on patients' drug use, as a means to centralize drug use, and as a transformative intervention for the hospital. In our findings, harm reduction, abstinence, security, and risk mitigation goals existed closely together, yielding overlaying realities.

CONCLUSION

Our findings revealed various enactments of an SCS, some of which are likely to negatively affect people who use drugs and service access. As more hospitals consider the implementation of an SCS, understanding how an SCS is made in practice will be key to building a service that focuses on the needs of people who use drugs.

Rapid hepatitis C virus point-of-care RNA testing and treatment at an integrated supervised consumption service in Toronto, Canada: a prospective, observational cohort study

Background

Despite high burden of Hepatitis C (HCV) among people who inject drugs, significant barriers to care persist. The aim of this study was to evaluate the provision of rapid, low-barrier point-of-care (POC) HCV RNA testing and linkage to care among clients of a supervised consumption service (SCS) located within a community health centre in Toronto, Canada. Secondary aims included measuring HCV RNA prevalence at baseline, HCV incidence during follow-up and exploring factors associated with HCV RNA positivity and treatment uptake.

Methods

Participants were enrolled in a prospective, observational cohort from August 13, 2018 to September 30, 2021. Those with positive HCV RNA tests were offered immediate referral to onsite treatment. Those with negative results were offered repeat testing every three months for up to four visits. HCV incidence was estimated as the number of incident HCV infections per 100 person-years at risk, among those HCV RNA negative at baseline who returned for ≥1 follow-up visit. Missing data were reported when present.

Findings

128 participants were enrolled with four later removed due to ineligibility. At baseline, 54 of 124 eligible participants (43.5%) tested HCV RNA positive. HCV incidence was 35.1 cases per 100 person-years (95% CI: 18.9-65.3) with a cumulative incidence of 38.3% at 15 months of follow-up. Among participants HCV RNA positive at baseline or follow-up (n = 64), 67.2% (n = 43) were linked to HCV care and treatment was initiated among 67.4% (n = 29/43).

Interpretation

High HCV RNA prevalence and incidence demonstrate that the SCS serves a high-risk population for HCV. Testing acceptance was high, as was treatment engagement. POC HCV RNA testing positions SCSs as an important point of HCV care access.

Funding

HCV Micro-Elimination Grant, Gilead Sciences Canada; in-kind support from Cepheid.

Integrated supervised consumption services and hepatitis C testing and treatment among people who inject drugs in Toronto, Canada: A cross-sectional analysis

Despite the availability of publicly funded hepatitis C (HCV) treatment in Canada, treatment gaps persist, particularly among people who inject drugs. We estimate correlates of HCV care cascade engagement (testing, diagnosis, and treatment) among people who inject drugs in Toronto, Canada and examine the effect of accessing differing supervised consumption service (SCS) models on self-reported HCV testing and treatment. This is a cross-sectional baseline analysis of 701 people who inject drugs surveyed in the Toronto, Ontario integrated Supervised Injection Services (OiSIS-Toronto) study between November 2018 and March 2020. We examine correlates of self-reported HCV care cascade outcomes including SCS model, demographic, socio-structural, drug use, and harm reduction characteristics. Overall, 647 participants (92%) reported ever receiving HCV testing, of whom 336 (52%) had been diagnosed with HCV. Among participants who reported ever being diagnosed with HCV, 281 (84%) reported chronic HCV, of whom 130 (46%) reported HCV treatment uptake and 151 (54%) remained untreated. Compared to those with no SCS use, participants who had ever injected at an integrated SCS model with co-located HCV care had greater prevalence of both ever receiving HCV testing (adjusted prevalence ratio [aPR]: 1.12, 95% confidence interval [CI]: 1.02-1.24) and ever receiving HCV treatment (aPR: 1.67, 95% CI: 1.04-2.69). Over half of participants diagnosed with chronic HCV reported remaining untreated. Our findings suggest that integrated SCS models with co-located HCV care represent key strategies for linkage to HCV care, but that more is needed to support scale-up.

Requiring help injecting among people who inject drugs in Toronto, Canada: Characterising the need to address sociodemographic disparities and substance-use specific patterns

INTRODUCTION

Those requiring help injecting are at an elevated risk of injection-related injury and blood-borne infections and are thus a priority group for harm reduction programs. As supervised consumption services (SCS) are scaled-up across Canada, information on those who require help injecting is necessary to inform equitable service uptake. We characterised the sociodemographic, structural and drug use correlates of needing help injecting among a cohort of people who inject drugs in Toronto, Canada.

METHODS

A cross-sectional baseline survey was administered between November 2018 and March 2020. Unadjusted and multivariable logistic regression models examined associations with requiring help injecting in the past 6 months. A gender-stratified sub-analysis described characteristics of receiving help among those requiring it.

RESULTS

Of 701 participants (31.0% cisgender women), 294 (41.9%) needed recent help injecting. In unadjusted analyses, being a racialised, non-Indigenous person (odds ratio [OR] 1.79, 95% confidence interval [CI] 1.13-2.86) or a cisgender woman (OR 1.72, 95% CI 1.24-2.39) were associated with needing help. In multivariable analyses, requiring assistance was associated with needing frequent help preparing drugs (adjusted OR [AOR] 9.52, 95% CI 4.78-21.28), fewer years since first injection (AOR for 1 year increase: 0.97, 95% CI 0.95-0.99) and injecting stimulants. Among those who required help, cisgender women reported needing assistance more often than cisgender men (P = 0.009).

DISCUSSION AND CONCLUSIONS

Over two-fifths of the sample required help injecting; requiring assistance was associated with sociodemographic indicators and substance use-specific patterns. Findings highlight the need to scale-up educational resources for those who receive or provide help injecting, as well as SCS that accommodate onsite injection assistance.

Evaluating interventions to facilitate opioid agonist treatment access among people who inject drugs in Toronto, Ontario during COVID-19 pandemic restrictions

Background

In March 2020, following a provincial COVID-19 emergency declaration, modifications to opioid agonist treatment (OAT) were introduced in Ontario, Canada to promote treatment access amid the pandemic and ongoing opioid overdose crisis. Modifications included federal exemptions to facilitate OAT prescription re-fills, extensions, and deliveries and interim treatment guidance emphasizing take-home (non-observed) doses and reduced urine drug screening for OAT patients.

Methods

We conducted an interrupted time series study using health administrative data from September 17^th, 2019–September 21^st, 2020, on 359 people who inject drugs with suspected opioid use disorder in Toronto, Ontario. We used segmented regression analyses to evaluate the joint effects of the provincial COVID-19 emergency declaration, federal OAT exemptions, and interim treatment guidance—all implemented between March 17^th–23^rd, 2020—on the weekly proportion of participants enrolled in OAT (i.e., ≥1 day(s) covered with methadone or buprenorphine/naloxone), with an opioid-related overdose (based on emergency department visits and hospitalizations), and who died (all-cause), and the weekly proportion of OAT-enrolled participants receiving take-home doses (i.e., ≥1 day(s) covered) and undergoing urine drug screening.

Results

Post-implementation, the interventions were associated with immediate absolute changes in OAT enrollment (+1.95%; 95% CI=0.04%–3.85%), receipt of take-home doses (+18.3%; 95% CI=13.2%–23.4%), and urine drug screening (-22.4%; 95% CI=[-26.9%]–[-17.9%]) and a gradual absolute increase of 0.56% in urine drug screening week-to-week (95% CI=0.27%–0.86%) beyond the pre-implementation trend. At 26 weeks post-implementation, OAT enrollment and urine drug screening approached pre-implementation levels whereas the increase in take-home doses was largely sustained (+15.0%; 95% CI=4.33%–25.6%). No post-implementation increases in opioid-related overdoses were observed. Death was not modelled (low event frequency).

Conclusion

Changes to OAT provision following provincial COVID-19 restrictions were associated with an immediate and sustained increase in take-home dose coverage among OAT-enrolled participants, without corresponding increases in opioid-related overdoses among all participants.

Service utilization patterns and characteristics among clients of integrated supervised consumption sites in Toronto, Canada

Introduction

Supervised consumption services (SCS), intended to reduce morbidity and mortality among people who inject drugs, have been implemented in a variety of delivery models. We describe and compare access to and uptake of co-located and external services among clients accessing harm reduction-embedded (HR-embedded) and community health center-embedded (CHC-embedded) SCS models.

Methods

Cross-sectional baseline data were collected between November 2018 and March 2020 as part of a cohort of people who inject drugs in Toronto, Canada designed to evaluate one HR-embedded and two CHC-embedded SCS. This analysis was restricted to clients who reported accessing these SCS more than once in the previous 6 months. Participants were classified as HR-embedded or CHC-embedded SCS clients based on self-reported usage patterns. Client characteristics, as well as access to onsite services and referral and uptake of external services, were compared by SCS model.

Results

Among 469 SCS clients, 305 (65.0%) primarily used HR-embedded SCS and 164 (35.0%) primarily used CHC-embedded SCS. Compared to clients accessing CHC-embedded SCS, clients accessing HR-embedded SCS were somewhat younger (37.6 vs. 41.4, p < 0.001), more likely to report fentanyl as their primary injected drug (62.6% vs. 42.7%, p < 0.001), and visited SCS more often (49.5% vs. 25.6% ≥ daily, p < 0.001). HR-embedded SCS clients were more likely to access harm reduction services onsite compared to CHC-embedded SCS clients (94.8% vs. 89.6%, p = 0.04), while CHC-embedded SCS clients were more likely to access non-harm reduction services onsite (57.3% vs. 26.6%, p < 0.001). For external services, HR-embedded SCS clients were more likely to receive a referral (p = 0.03) but less likely to report referral uptake (p = 0.009).

Conclusions

Clients accessing HR-embedded and CHC-embedded SCS were largely demographically similar but had different drug and SCS use patterns, with CHC-embedded SCS clients using the site less frequently. While clients of CHC-embedded SCS reported greater access to ancillary health services onsite, external service use remained moderate overall, underscoring the importance of co-location and support for clients with system navigation. Importantly, lack of capacity in services across the system may impact ability of staff to make referrals and/or the ability of clients to take up a referral.

Validation of Self-reported Opioid Agonist Treatment Among People Who Inject Drugs Using Prescription Dispensation Records

BACKGROUND

Studies of people who inject drugs (PWID) commonly use questionnaires to determine whether participants are currently, or have recently been, on opioid agonist treatment for opioid use disorder. However, these previously unvalidated self-reported treatment measures may be susceptible to inaccurate reporting.

METHODS

We linked baseline questionnaire data from 521 PWID in the Ontario integrated Supervised Injection Services cohort in Toronto (November 2018-March 2020) with record-level health administrative data. We assessed the validity (sensitivity, specificity, positive and negative predictive value [PPV and NPV]) of self-reported recent (in the past 6 months) and current (as of interview) opioid agonist treatment with methadone or buprenorphine-naloxone relative to prescription dispensation records from a provincial narcotics monitoring system, considered the reference standard.

RESULTS

For self-reported recent opioid agonist treatment, sensitivity was 78% (95% CI = 72, 83), specificity was 90% (95% CI = 86, 94), PPV was 90% (95% CI = 85, 93), and NPV was 79% (95% CI = 74, 84). For self-reported current opioid agonist treatment, sensitivity was 84% (95% CI = 78, 90), specificity was 87% (95% CI = 83, 91), PPV was 74% (95% CI = 67, 81), and NPV was 93% (95% CI = 89, 95).

CONCLUSIONS

Self-reported opioid agonist treatment measures were fairly accurate among PWID, with some exceptions. Inaccurate recall due to a lengthy lookback window may explain underreporting of recent treatment, whereas social desirability bias may have led to overreporting of current treatment. These validation data could be used in future studies of PWID to adjust for misclassification in similar self-reported treatment measures.