Hydromorphone and the risk of infective endocarditis among people who inject drugs: a population-based, retrospective cohort study

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.

Controlled-release hydromorphone and risk of infection in adults: a systematic review

BACKGROUND

Preliminary evidence suggests that people who inject drugs (PWID) may be at an increased risk of developing infective endocarditis (IE), hepatitis C virus (HCV) infection, and/or human immunodeficiency virus (HIV) infection from hydromorphone controlled-release formulation. The hypothesized mechanism is related to insolubility of the drug, which promotes reuse, leading to contamination of injecting equipment. However, this relationship has not been confirmed. We aimed to conduct a systematic review including adult PWID exposed to controlled-release hydromorphone and the risk of acquiring IE, HCV, and HIV.

METHODS

We searched MEDLINE, EMBASE, and Evidence Based Medicine reviews from inception until September 2021. Following pilot testing, two reviewers conducted all screening of citations and full-text articles, as well as abstracted data, and appraised risk of bias using the Newcastle-Ottawa scale and Effective Practice and Organization of Care tool. Equity issues were examined using the PROGRESS-PLUS framework. Discrepancies were resolved consistently by a third reviewer. Meta-analysis was not feasible due to heterogeneity across the studies.

RESULTS

After screening 3,231 citations from electronic databases, 722 citations from unpublished sources/reference scanning, and 626 full-text articles, five studies were included. Five were cohort studies, and one was a case-control study. The risk of bias varied across the studies. Two studies reported on gender, as well as other PROGRESS-PLUS criteria (race, housing, and employment). Three studies focused specifically on the controlled-release formulation of hydromorphone, whereas two studies focused on all formulations of hydromorphone. One retrospective cohort study found an association between controlled-release hydromorphone and IE, whereas a case-control study found no evidence of an association. One retrospective cohort study found an association between the number of hydromorphone controlled-release prescriptions and prevalence of HCV. None of the studies specifically reported on associations with HIV.

DISCUSSION

Very few studies have examined the risk of IE, HCV, and HIV infection after exposure to controlled-release hydromorphone. Very low-quality and scant evidence suggests uncertainty around the risks of blood-borne infections, such as HCV and IE to PWID using this medication.

The Epidemiology of Infective Endocarditis in New South Wales, Australia: A Retrospective Cross-Sectional Study From 2001 to 2020

OBJECTIVES

This study aimed to investigate the demographic differences amongst patients diagnosed with infective endocarditis (IE), predictors of adverse events, and the association between clinical decision-making and adverse health outcomes amongst patients with IE.

DESIGN

A retrospective cross-sectional study was conducted using the New South Wales (NSW) Admitted Patient Data Collection (APDC) from the Centre for Health Record Linkage (CHeReL).

PARTICIPANTS

All patients (N=18,044) from 2001 to 2020 in New South Wales who received a diagnosis of IE using ICD-10-AM diagnostic code 133.0 were included.

METHODS

Categorical variables were compared using the chi-square test or Fisher's exact test, while the t-test was used for continuous variables. The association between clinical decision-making and adverse health outcomes amongst patients with IE were examined via generalised linear mixed models.

RESULTS

Sex, age, birthplace and referral impacted clinical decision-making, in-hospital death and severity of the disease. Women experienced a higher risk of death and fewer escalations of care. Admission and mortality increased with age, with those aged 60 and above responsible for 60.8% of hospitalisations. Despite octogenarians making up one-fifth of admissions and having the worst mortality rate (15.1%), they experienced only one in 10 intensive care (ICU) admissions. Overseas-born patients had fewer escalations of care and experienced less severe disease if referred by a medical practitioner. One out of 10 admissions that resulted in a hospital death were given non-emergency status, and one in two ICU patients died in hospital.

CONCLUSIONS

Sex, age, place of birth, and clinical decision-making were important predictors of severe disease and death in hospital, lending weight that health care clinical decisions may adversely impact health outcomes for populations of interest.

Sensitivity, specificity and predictive values of ICD-10 substance use codes in a cohort of substance use-related endocarditis patients

Background: Healthcare databases have the potential to become efficient tools for epidemiological research in People Who Inject Drugs (PWID). The validity of ICD-10 codes for specific substances in this population has not been assessed.Objectives: Validate ICD-10 diagnosis codes relating to the use of specific substance classes in a cohort of endocarditis patients.Methods: Our study sample consisted of 379 first-episode infective endocarditis patients (Male: 208, Female: 171), aged 18-55, admitted to any of three hospitals in London, Ontario from 2007 to 2018. Of these, 287 used drugs. We validated ICD-10 substance use codes for opioids (F11), stimulants (F15), cocaine (F14) and multiple substances (F19). Sensitivity, specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) were calculated for each code, using self-reported substance use documented on medical record review as a gold standard. We conducted a comparative analysis between code-negative users and code-positive users for each substance.Results: All substance use codes shared the same pattern: high specificity, high PPV and low sensitivity, with code F11 yielding the highest PPV (96.3%; 95% C.I.: 90.8-98.6) and sensitivity (42.6%; 95% C.I. 36.3-49.1). The code-positives and code-negatives for each substance did not differ significantly in any characteristics compared.Conclusion: Our results suggest that the individual ICD-10 codes analyzed should not be used for research without adjustment for low sensitivity. However, due to high PPV and specificity, these codes may still have potential for research use. Because code-negative patients did not differ from code-positive patients, their data may be extrapolated to the overall group of substance users.

Peripherally Inserted Central Catheter Line Misuse Among People Who Inject Drugs While on Therapy for Infective Endocarditis

BACKGROUND

People who inject drugs and have infective endocarditis have a high risk of recurrent infective endocarditis and death. We aimed to characterize clinical factors associated with mortality and assess the probability of infective endocarditis recurrence in the presence of death as a competing risk.

METHODS

A retrospective cohort study was conducted of people who inject drugs, identified between April 5, 2007 and March 15, 2018 with the Modified Duke Criteria for definite infective endocarditis. Fine-Gray sub-distribution and Cox proportional hazards modeling were conducted to determine variables associated with the rate of infective endocarditis recurrence and mortality, respectively.

RESULTS

Of the 310 patients with infective endocarditis who inject drugs, 236 experienced a single episode and 74 experienced recurrent episodes. Peripherally inserted central catheter misuse was associated with an increased rate of infective endocarditis recurrence (sub-distribution hazard ratio 2.41; 95% confidence interval [CI], 1.17-4.98; P = .02) and mortality (hazard ratio [HR] 2.44; 95% CI, 1.15-5.17; P = .02). Non-right-sided infection, peripheral intravenous therapy, and intensive care unit admission were also associated with increased mortality. Oral therapy (HR 0.38; 95% CI, 0.16-0.91; P = .03), outpatient treatment (HR 0.39; 95% CI, 0.19-0.82; P = .01), and inpatient referral to addiction services (HR 0.39; 95% CI, 0.22-0.70; P = .002) were associated with a decrease in mortality.

CONCLUSIONS

Patients who misuse their peripherally inserted central catheter are at higher risk of recurrent infective endocarditis and death. Avoidance of peripherally inserted central catheter lines and use of intravenous peripheral therapy did not reduce mortality, but oral therapy was associated with reduced risk. Inpatient addiction services referral is important.

Different drugs, different sides: injection use of opioids alone, and not stimulants alone, predisposes to right-sided endocarditis

Objectives

Many studies suggest that infective endocarditis (IE) in people who inject drugs is predominantly right sided, while other studies suggest left sided disease; few have differentiated by class of drug used. We hypothesised that based on differing physiological mechanisms, opioids but not stimulants would be associated with right sided IE.

Methods

A retrospective case series of 290 adult (age ≥18) patients with self-reported recent injection drug use, admitted for a first episode of IE to one of three hospitals in London Ontario between April 2007 and March 2018, stratified patients by drug class used (opioid, stimulant or both), and by site of endocarditis. Other outcomes captured included demographics, causative organisms, cardiac and non-cardiac complications, referral to addiction services, medical versus surgical management, and survival.

Results

Of those who injected only opioids, 47/71 (69%) developed right-sided IE, 17/71 (25%) developed left-sided IE and 4/71 (6%) had bilateral IE. Of those who injected only stimulants, 11/24 (46%) developed right-sided IE, 11/24 (46%) developed left-sided IE and 2/24 (8%) had bilateral IE. Relative to opioid-only users, stimulant-only users were 1.75 (95% CI 1.05 to 2.93; p=0.031) times more likely to have a left or bilateral IE versus right IE.

Conclusions

While injection use of opioids is associated with a strong predisposition to right-sided IE, stimulants differ in producing a balanced ratio of right and left-sided disease. As the epidemic of crystal methamphetamine injection continues unabated, the rate of left-sided disease, with its attendant higher morbidity and mortality, may also grow.

Characterizing safer supply prescribing of immediate release hydromorphone for individuals with opioid use disorder across Ontario, Canada

BACKGROUND

In response to the ongoing overdose crisis, some clinicians in Canada have started prescribing immediate release hydromorphone (IRH) as an alternative to the toxic unregulated drug supply. This practice is often referred to as safer supply. We aimed to identify and characterize patients receiving safer supply IRH and their prescribers in Ontario.

METHODS

Using provincial administrative health data, we identified individuals with opioid use disorder prescribed safer supply IRH from January 2016 to March 2020 and reported the number of initiations over time. We summarized demographic, health, and medication use characteristics among patients who received safer supply IRH, and examined select clinical outcomes including retention and death. Finally, we characterized prescribers of safer supply IRH and compared frequent and infrequent prescribers.

RESULTS

We identified 534 initiations of safer supply IRH (447 distinct individuals) from 155 prescribers. Initiations increased over time with a peak in the third quarter of 2019 (103 initiations). Patients' median age was 42 (interquartile range [IQR] 34-50), and most were male (60.2%), urban residents, (96.2%), and in the lowest neighborhood income quintile (55.7%), with 13.9% having overdosed in the previous one year. The prevalence of HIV was 13.9%. The median duration on IRH was 272 days (IQR 30-1,244) and OAT was co-prescribed in 62.9% of courses. Death while receiving IRH or within 7 days of discontinuation was rare (≤5 courses;≤0.94 per person-year for each).

CONCLUSIONS

Clinicians are increasingly prescribing safer supply IRH in Ontario. Patients prescribed safer supply IRH had demographic and clinical characteristics associated with high risk of death from opioid-related overdose. Short-term deaths among people receiving safer supply IRH were rare.

Correlates of 90-day Mortality Among People Who Do and Do Not Inject Drugs with Infective Endocarditis in Seattle, Washington

Background

Infective endocarditis (IE) remains highly morbid, but few studies have evaluated factors associated with IE mortality. We examined correlates of 90-day mortality among people who inject drugs (PWID) and people who do not inject drugs (non-PWID).

Methods

We queried the electronic medical record for cases of IE among adults ≥18 years of age at 2 academic medical centers in Seattle, Washington, from 1 January 2014 to 31 July 2019. Cases were reviewed to confirm a diagnosis of IE and drug use status. Deaths were confirmed through the Washington State death index. Descriptive statistics were used to characterize IE in PWID and non-PWID. Kaplan-Meier log-rank tests and Cox proportional hazard models were used to assess correlates of 90-day mortality.

Results

We identified 507 patients with IE, 213 (42%) of whom were PWID. Sixteen percent of patients died within 90 days of admission, including 14% of PWID and 17% of non-PWID (P = .50). In a multivariable Cox proportional hazard model, injection drug use was associated with a higher mortality within the first 14 days of admission (adjusted hazard ratio [aHR], 2.33 [95% confidence interval {CI}, 1.16–4.65], P = .02); however, there was no association between injection drug use and mortality between 15 and 90 days of admission (aHR, 0.63 [95% CI, .31–1.30], P = .21).

Conclusions

Overall 90-day mortality did not differ between PWID and non-PWID with IE, although PWID experienced a higher risk of death within 14 days of admission. These findings suggest that early IE diagnosis and treatment among PWID is critical to improving outcomes.

Unequal access to opioid agonist treatment and sterile injecting equipment among hospitalized patients with injection drug use-associated infective endocarditis

BACKGROUND

Addiction treatment and harm reduction services reduce risks of death and re-infection among patients with injection drug use-associated infective endocarditis (IDU-IE), but these are not offered at many hospitals. Among hospitalized patients with IDU-IE at the two tertiary-care hospitals in the Canadian Maritimes, we aimed to identify (1) the availability of opioid agonist treatment (OAT) and sterile drug injecting equipment, and (2) indicators of potential unmet addiction care needs.

METHODS

Retrospective review of IDU-IE hospitalizations at Queen Elizabeth II Health Sciences Centre (Halifax, Nova Scotia) and the Saint John Regional Hospital (Saint John, New Brunswick), October 2015 -March 2017. In Halifax, there are no addiction medicine providers on staff; in Saint John, infectious diseases physicians also practice addiction medicine. Inclusion criteria were: (1) probable or definite IE as defined by the modified Duke criteria; and (2) injection drug use within the prior 3 months.

RESULTS

We identified 38 hospitalizations (21 in Halifax and 17 in Saint John), for 30 unique patients. Among patients with IDU-IE and untreated opioid use disorder, OAT was offered to 36% (5/14) of patients in Halifax and 100% (6/6) of patients in Saint John. Once it was offered, most patients at both sites initiated OAT and planned to continue it after discharge. In Halifax, no patients were offered sterile injecting equipment, and during five hospitalizations staff confiscated patients' own equipment. In Saint John, four patients were offered (and one was provided) injecting equipment in hospital, and during two hospitalizations staff confiscated patients' own equipment. Concerns regarding undertreated pain or opioid withdrawal were documented during 66% (25/38) of hospitalizations, and in-hospital illicit or non-medical drug use during 32% (12/38). Two patients at each site (11%; 4/38) had self-directed discharges against medical advice.

CONCLUSIONS

Patients with IDU-IE in the Canadian Maritimes have unequal access to evidence-based addiction care depending on where they are hospitalized, which differs from the community-based standard of care. Indicators of potential unmet addiction care needs in hospital were common.

Trends in Hospitalizations for Serious Infections Among People With Opioid Use Disorder in Ontario, Canada

Opioid use among people who inject drugs can lead to serious complications, including infections. We sought to study trends in rates of these complications among people with an opioid use disorder (OUD) and the sequelae of those hospitalizations.

Impact of the Opioid Epidemic

In recent years the prescription opioid overdose epidemic has decreased, but has been more than offset by increases in overdose caused by fentanyl and fentanyl analogues. Opioid overdose patients should receive naloxone if they have significant respiratory depression and/or loss of protective airway reflexes. Patients who receive naloxone should be observed for recurrent opioid effects. Patients with opioid overdose may be admitted to the intensive care unit for naloxone infusions, treatment of noncardiogenic pulmonary edema, autonomic instability, or sequelae of hypoxia-ischemia or cardiac arrest. Primary and secondary prevention are important to reduce the number of people with life-threatening opioid overdose.

Social and structural determinants of injecting-related bacterial and fungal infections among people who inject drugs: protocol for a mixed studies systematic review

INTRODUCTION

Injecting-related bacterial and fungal infections are a common complication among people who inject drugs (PWID), associated with significant morbidity and mortality. Invasive infections, including infective endocarditis, appear to be increasing in incidence. To date, preventive efforts have focused on modifying individual-level risk behaviours (eg, hand-washing and skin-cleaning) without much success in reducing the population-level impact of these infections. Learning from successes in HIV prevention, there may be great value in looking beyond individual-level risk behaviours to the social determinants of health. Specifically, the risk environment conceptual framework identifies how social, physical, economic and political environmental factors facilitate and constrain individual behaviour, and therefore influence health outcomes. Understanding the social and structural determinants of injecting-related bacterial and fungal infections could help to identify new targets for prevention efforts in the face of increasing incidence of severe disease.

METHODS AND ANALYSIS

This is a protocol for a systematic review. We will review studies of PWID and investigate associations between risk factors (both individual-level and social/structural-level) and the incidence of hospitalisation or death due to injecting-related bacterial infections (skin and soft-tissue infections, bacteraemia, infective endocarditis, osteomyelitis, septic arthritis, epidural abscess and others). We will include quantitative, qualitative and mixed methods studies. Using directed content analysis, we will code risk factors for these infection-related outcomes according to their contributions to the risk environment in type (social, physical, economic or political) and level (microenvironmental or macroenvironmental). We will also code and present risk factors at each stage in the process of drug acquisition, preparation, injection, superficial infection care, severe infection care or hospitalisation, and outcomes after infection or hospital discharge.

ETHICS AND DISSEMINATION

As an analysis of the published literature, no ethics approval is required. The findings will inform a research agenda to develop and implement social/structural interventions aimed at reducing the burden of disease.

PROSPERO REGISTRATION NUMBER

CRD42021231411.

Exploring care of hospital inpatients with substance involvement

INTRODUCTION

This article presents demographic and care factors related to persons who are substance-involved and require inpatient administration of intravenous antibiotics.

PURPOSE

This study was conducted to explore healthcare responses to support substance-involved inpatients, through exploration of documented client outcomes, healthcare provider accounts, and representation of clients through documentation.

METHOD(S)

A patient-oriented research team undertook this multiple methods, exploratory study. A health record review included people admitted to a complex continuing care hospital, within a 2-year period, for long-term antibiotic treatment and concurrent illicit substance use. Correlations were examined between whether or not clients were discharged against medical advice (AMA) in comparison to demographic, medical, and care-related factors. Qualitative analysis of narrative health record data was undertaken. Semi-structured interviews of healthcare providers and decision makers were conducted.

RESULTS

Twenty-five people met recruitment criteria for health record review; three people were admitted twice, resulting in 28 admissions. Interviews with seven healthcare providers and decision makers uncovered themes of client autonomy, professional liability, client responsibility, the "right" service, and burnout, hopelessness, and helplessness.

CONCLUSION

Recommended strategies to effectively respond to substance use among clients admitted for general medical concerns are: i) support inpatients with complex health needs, including substance use, ii) ensure substance use and addiction services are integrated into all inpatient practice areas, iii) support effective harm reduction practices for hospital-admitted clients, and iv) develop robust policies and protocols to support healthcare providers and inpatients.

Soft Tissue, Bone, and Joint Infections in People Who Inject Drugs

Infections are a common complication among people who inject drugs (PWID). Skin and soft tissue infections (SSTI) as well as bone and joint infections comprise a significant source of morbidity and mortality among this population. The appropriate recognition and management of these infections are critical for providers, as is familiarity with harm-reduction strategies. This review provides an overview of the presentation and management of SSTI and bone and joint infections among PWID, as well as key prevention measures that providers can take.

Hospital admissions and mortality due to complications of injection drug use in two hospitals in Regina, Canada: retrospective chart review

BACKGROUND

Infectious complications of injection drug use (IDU) often require lengthy inpatient treatment. Our objective was to identify the number of admissions related to IDU in Regina, Canada, as well as describe patient demographics and comorbidities, yearly mortality, readmission rate, and cumulative cost of these hospitalizations between January 1 and December 31, 2018. Additionally, we sought to identify factors that increased risk of death or readmission.

METHODS

This study is a retrospective chart review conducted at the two hospitals in Regina. Eligible study cases were identified by querying the discharge database for predetermined International Classification of Diseases code combinations. Electronic medical records were reviewed to assess whether each admission met inclusion criteria, and hospitalization and patient data were subsequently extracted for all included admissions. Mortality data were gleaned from hospital and Ministry of Health databases. Data were analyzed using Excel and IBM SPSS Statistics to identify common comorbidities, admission diagnoses, and costs, as well as to compare patients with a single admission during the study period to those with multiple admissions. Logistic regression analysis was used to identify the relationship between individual variables and in- and out-of-hospital annual mortality.

RESULTS

One hundred and forty-nine admissions were included, with 102 unique patients identified. Common comorbidities included hepatitis C (47%), human immunodeficiency virus (HIV) (25%), and comorbid psychiatric disorders (19%). In 23% of all admissions, patients left hospital prior to treatment completion, and 27% of patients experienced multiple admissions. Female patients and those with chronic pain were more likely to be readmitted (p = 0.024 and p = 0.029, respectively). Patients admitted with infective endocarditis were more likely to die during hospitalization (p = 0.0001). The overall mortality was 15% in our cohort. The estimated cumulative cost of inpatient treatment of complications of IDU in Regina was $3.7 million CAD in 2018.

CONCLUSION

Patients with history of IDU and hospital admission experience high mortality rates in Regina, a city with paucity of inpatient supports for persons who use injection drugs. Needle syringe programs, opioid agonist therapy, and safe consumption sites have been shown to improve outcomes as well as reduce healthcare costs for this patient population. We will use our findings to advocate for increased access to these harm reduction strategies in Regina, particularly for inpatients.

Relative addictive potential of opioid analgesic agents

Opioid overdoses and deaths continue to be a problem in the USA with a significant portion related to prescribed opioid analgesic agents. The role of pharmacogentic factors in opioid addiction is an active area of research. While all opioid analgesic agents have some addictive potential, it is clear that there are some with greater addictive potential. Oxycodone is the most widely abused opioid analgesic and it appears to predispose to chronic use with high likability by users. Fentanyl and hydromorphone are both very lipophilic allowing rapid penetration into the CNS, but are not rated as highly as other agents. Providers should consider the risk of addiction with the opioids they prescribe and give those with a lower addictive potential.

Evaluating differences in opioid and stimulant use-associated infectious disease hospitalizations in Florida, 2016-2017

Background

The opioid epidemic has led to increases in injection drug use (IDU)-associated infectious diseases; however, little is known about how more recent increases in stimulant use have affected the incidence and outcomes of hospitalizations for infections among people who inject drugs (PWID).

Methods

All hospitalizations of PWID for IDU-associated infections in Florida were identified using administrative diagnostic codes and were grouped by substance used (opioids, stimulants, or both) and site of infection. We evaluated the association between substance used and the outcomes: patient-directed discharge (PDD, or “against medical advice”) and in-hospital mortality.

Results

There were 22 856 hospitalizations for infections among PWID. Opioid use was present in 73%, any stimulants in 43%, and stimulants-only in 27%. Skin and soft tissue infection was present in 50%, sepsis/bacteremia in 52%, osteomyelitis in 10%, and endocarditis in 10%. PWID using opioids/stimulants were youngest, most uninsured, and had the highest rates of endocarditis (16%) and hepatitis C (44%). Additionally, 25% of patients with opioid/stimulant use had PDD versus 12% for those using opioids-only. In adjusted models, opioid/stimulant use was associated with PDD compared to opioid-only use (aRR 1.28, 95% CI 1.17–1.40). Younger age and endocarditis were also associated with PDD. Compared to opioid-only use, stimulant-only use had higher risk of in-hospital mortality (aRR 1.26, 95% CI 1.03–1.46).

Conclusions

While opioid use contributed to most IDU-associated infections, many hospitalizations also involved stimulants. Increasing access to harm reduction interventions could help prevent these infections, while further research on the acute management of stimulant use disorder-associated infections is needed.

Risk factors of infective endocarditis in persons who inject drugs

BACKGROUND

The rising incidence of infective endocarditis (IE) among people who inject drugs (PWID) has been a major concern across North America. The coincident rise in IE and change of drug preference to hydromorphone controlled-release (CR) among our PWID population in London, Ontario intrigued us to study the details of injection practices leading to IE, which have not been well characterized in literature.

METHODS

A case-control study, using one-on-one interviews to understand risk factors and injection practices associated with IE among PWID was conducted. Eligible participants included those who had injected drugs within the last 3 months, were > 18  years old and either never had or were currently admitted for an IE episode. Cases were recruited from the tertiary care centers and controls without IE were recruited from outpatient clinics and addiction clinics in London, Ontario.

RESULTS

Thirty three cases (PWID IE+) and 102 controls (PWID but IE-) were interviewed. Multivariable logistic regressions showed that the odds of having IE were 4.65 times higher among females (95% CI 1.85, 12.28; p = 0.001) and 5.76 times higher among PWID who did not use clean injection equipment from the provincial distribution networks (95% CI 2.37, 14.91; p < 0.001). Injecting into multiple sites and heating hydromorphone-CR prior to injection were not found to be significantly associated with IE. Hydromorphone-CR was the most commonly injected drug in both groups (90.9% cases; 81.4% controls; p = 0.197).

DISCUSSION

Our study highlights the importance of distributing clean injection materials for IE prevention. Furthermore, our study showcases that females are at higher risk of IE, which is contrary to the reported literature. Gender differences in injection techniques, which may place women at higher risk of IE, require further study. We suspect that the very high prevalence of hydromorphone-CR use made our sample size too small to identify a significant association between its use and IE, which has been established in the literature.

Tackling the overdose crisis: The role of safe supply

North America is experiencing an unprecedented overdose crisis driven by the proliferation of fentanyl and its analogues in the illicit drug supply. In 2018 there were 67,367 drug overdose deaths in the United States, and since 2016, there have been more than 14,700 overdose deaths in Canada, with most related to fentanyl. Despite concerted efforts and some positive progress, current public health, substance use treatment, and harm reduction interventions (such as widespread naloxone distribution and implementation of supervised consumption sites) have not been able to rapidly decrease overdose fatalities. In view of the persistent gaps in services and the limitations of available options, immediate scale-up of low-barrier opioid distribution programs are urgently needed. This includes "off-label" prescription of pharmaceutical grade opioids (e.g., hydromorphone) to disrupt the toxic drug supply and make safer opioids widely available to people at high risk of fatal overdose.