The role of living context in prescription opioid injection and the associated risk of hepatitis C infection

Effect of incarceration and opioid agonist treatment transitions on risk of hospitalisation with injection drug use-associated bacterial infections: A self-controlled case series in New South Wales, Australia

BACKGROUND

Transitional times in opioid use, such as release from prison and discontinuation of opioid agonist treatment (OAT), are associated with health harms due to changing drug consumption practices and limited access to health and social supports. Using a self-controlled (within-person) study design, we aimed to understand if these transitions increase risks of injection drug use-associated bacterial infections.

METHODS

We performed a self-controlled case series among a cohort of people with opioid use disorder (who had all previously accessed OAT) in New South Wales, Australia, 2001-2018. The outcome was hospitalisation with injecting-related bacterial infections. We divided participants' observed days into time windows related to incarceration and OAT receipt. We compared hospitalization rates during focal (exposure) windows and referent (control) windows (i.e., 5-52 weeks continuously not incarcerated or continuously receiving OAT). We estimated adjusted incidence rate ratios (aIRR) using conditional logistic regression, adjusted for time-varying confounders.

RESULTS

There were 7590 participants who experienced hospitalisation with injecting-related bacterial infections (35% female; median age 38 years; 78% hospitalised with skin and soft-tissue infections). Risk for injecting-related bacterial infections was elevated for two weeks following release from prison (aIRR 1.45; 95%CI 1.22-1.72). Risk was increased during two weeks before (aIRR 1.89; 95%CI 1.59-2.25) and after (aIRR 1.91; 95%CI 1.54-2.36) discontinuation of OAT, and during two weeks before (aIRR 3.63; 95%CI 3.13-4.22) and after (aIRR 2.52; 95%CI 2.09-3.04) OAT initiation.

CONCLUSION

Risk of injecting-related bacterial infections varies greatly within-individuals over time. Risk is raised immediately after prison release, and around initiation and discontinuation of OAT. Social contextual factors likely contribute to excess risks at transitions in incarceration and OAT exposure.

Injection drug use in an affluent beachside community in Sydney: An exploratory qualitative study

INTRODUCTION

Social research on injection drug use has focussed on marginalised groups and communities, leaving a large gap in the field's understanding of how it is experienced in other settings, including in relatively affluent communities.

METHODS

This research is based on fieldwork and 18 in-depth qualitative interviews conducted in suburban beach-side communities in Sydney collectively known as the Northern Beaches.

RESULTS

Participants did not experience stigmatisation by local health services as the norm or as a deterrent to access. Drug acquisition on the Northern Beaches occurred among closed networks of friends and acquaintances, and injecting use rarely occurred in public settings. Police contact was minimal, resulting in lower levels of criminalisation.

DISCUSSION AND CONCLUSIONS

Unlike many of the participants featured in the literature, our study participants grew up in middle and upper middle-class households, typically experiencing comfortable childhoods with little to no exposure to injection drug use. In this setting injection drug use operates covertly within the normal rhythms of middle-class life, hidden in amongst the bustle of cafés and shopping centres, and through the friendliness of neighbourhood driveway and doorstep interactions. Drug use is described as common in the area, with injecting behaviours stigmatised in ways that set it against the 'good' families and neighbourhoods of this beach-side enclave. In contrast to much of the Australian qualitative literature which frames injection drug use as a means of psychological relief or a subcultural norm, our participants described injecting as motivated by the desire to enhance pleasure and social connection.

Effect of HCV or HIV infection on mortality among hospitalized persons who used opioids, 2000-2010

Mortality due to opioid misuse and overdose has increased substantially in the United States over the past two decades. The study objective was to describe the causes of death among persons with opioid-related hospitalizations and examine survival by Hepatitis C virus (HCV) or HIV. Opioid-related hospitalization records in Pennsylvania from 2000 to 2010 were linked to death registry files to assess cause of death, and survival from first hospital discharge date to death date, or December 31, 2010. Accelerated failure time models were used to compare survival between persons with and without HCV or HIV diagnoses. Among the 136,416 individuals with an opioid-related hospitalization, 13.0% died over a median of 56 months of follow-up; the most common causes of death were circulatory diseases (26.4%) and drug overdose (23.5%). There were 27,122 (19.9%) and 3662 (2.7%) persons who had an HCV and HIV diagnosis, respectively. Among patients aged ≥20 years, those with HCV had shorter survival time compared to those without HCV, with discrepancies more pronounced at older ages. Patients with HIV also had shorter survival time (time ratio: 0.29 [95% CI: 0.26, 0.34]) compared to without HIV. These findings show that in a cohort of patients with opioid-related hospitalizations, those with HCV or HIV diagnoses have shorter survival. This has public health implications, providing further evidence that medical providers should educate patients who use opioids about the risks of HCV and HIV infection and focus prevention and treatment to decrease mortality among patients hospitalized for opioid use.

Social-Structural Predictors of Fentanyl Exposure among Street Involved Youth

ObjectiveThe emergence of synthetic fentanyl has been a main contributor to North America's rising overdose death rates. While increasing attention has been given to drug-related harm among youth, little is known about how social-structural conditions influence their risk of fentanyl exposure. Therefore, we evaluated potential relationships between social-structural conditions and fentanyl exposure among youth who use illicit drugs in Vancouver, BC. Methods: Data were derived from the At-Risk Youth Study (ARYS), a prospective cohort study. The ARYS cohort involves street-involved youth, who use illicit substances in Vancouver, Canada. A multivariable logic regression analysis model was used to identify social factors associated with recent fentanyl exposure as determined through urine drug screening. Results: Overall, 423 participants were included in this analysis, with 380 (38.23%) testing positive for recent fentanyl exposure. In a multivariable relative risk analysis, living in Vancouver's Downtown Eastside in the last six months (RR = 1.16, 95% CI: 1.03-1.32) and daily heroin injection drug use (RR = 1.31, 95% CI: 1.15 - 1.50) were positively associated with fentanyl exposure. As a secondary measure, we found that within the encounters who denied using fentanyl (92.25% of total encounters), 321 (35.05%) still tested positive. Conclusions: We found that youth residing in Vancouver's Downtown Eastside was positively associated with being exposed to fentanyl. Our findings highlight the need to support youth in finding secure housing outside of Vancouver's drug use epicenter to reduce fentanyl exposure.

Injecting frequency trajectories and hepatitis C virus acquisition: Findings from a cohort of people who inject drugs in Montréal, Canada

BACKGROUND

Frequent injecting increases hepatitis C (HCV) acquisition risk among people who inject drugs (PWID). However, few studies have examined how temporal fluctuations in injecting frequency may effect HCV infection risk. Thus, this study examined HCV incidence according to injecting frequency trajectories followed by PWID over one year in Montréal, Canada.

METHODS

At three-month intervals from March 2011 to June 2016, HCV-uninfected PWID (never infected or cleared infection) enrolled in the Hepatitis Cohort (HEPCO) completed interviewer-administered questionnaires and HCV testing. At each visit, participants reported the number of injecting days (0-30 days) for each of the past three months. In previous work, using group-based trajectory modeling, we identified five injecting frequency trajectories followed by participants over one year (months 1-12 of follow-up), including sporadic, infrequent, increasing, decreasing, and frequent injecting. In this study, we estimated group-specific HCV incidence (months 1-63 of follow-up) using posterior probabilities to assign participants to their most likely trajectory group.

RESULTS

Of 386 participants (mean age=40, 82% male, 48% never HCV-infected), 72 acquired HCV during 893 person-years of follow-up. HCV incidence for the whole study sample was 8.1 per 100 person-years (95%CI=6.4-10.1). Trajectory group-specific HCV incidences were highest for those injecting drugs with decreasing (23.9, 14.4-37.5) or increasing frequency (16.0, 10.1-24.3), intermediate for those injecting at consistently high frequency (10.2, 5.4-17.8), and lowest for those injecting infrequently (3.9, 2.2-6.5) or sporadically (4.3, 2.2-7.6).

CONCLUSION

Results suggest that PWID at highest HCV risk are those injecting at high frequency, either transitorily (increasing, decreasing injecting) or consistently (frequent injecting). This study highlights changes in injecting frequency as a potentially important dimension to consider among the factors leading to HCV acquisition. Clinical and public health interventions tailored to PWID with different injecting frequency profiles may contribute to HCV prevention.

Associations between housing stability and injecting frequency fluctuations: findings from a cohort of people who inject drugs in Montréal, Canada

BACKGROUND

The relationship between housing stability and drug injecting is complex, as both outcomes fluctuate over time. The objectives were to identify short-term trajectories of housing stability and injecting frequency among people who inject drugs (PWID) and examine how patterns of injecting frequency relate to those of housing stability.

METHODS

At three-month intervals, PWID enrolled between 2011 and 2016 in the Hepatitis Cohort completed an interviewer-administered questionnaire and were tested for hepatitis C and HIV infections. At each visit, participants reported, for each of the past three months, the accommodation they lived in the longest (stable/unstable) and the number of injecting days (0-30). Group-based dual trajectory modeling was conducted to identify housing stability and injecting frequency trajectories evolving concomitantly over 12 months and estimate the probabilities of following injecting trajectories conditional upon housing trajectories.

RESULTS

386 participants were included (mean age 40.0, 82 % male). Three housing stability trajectories were identified: sustained (53 %), declining (20 %), and improving (27 %). Five injecting frequency trajectories were identified: sporadic (26 %), infrequent (34 %), increasing (15 %), decreasing (11 %), and frequent (13 %). PWID with improving housing were less likely to increase injecting (8 %) compared to those with sustained (17 %) or declining housing (17 %).

CONCLUSIONS

Improving housing was associated with a lower probability of increasing injecting compared to declining housing, while sustained housing stability was associated with a higher probability of increasing injecting compared to improving housing. Therefore, policies to improve PWID's access to stable housing are warranted and may reduce, to some extent, drug injecting and related harms.

Short and sporadic injecting cessation episodes as predictors of incident hepatitis C virus infection: findings from a cohort study of people who inject drugs in Montréal, Canada

BACKGROUND AND AIMS

For most people who inject drugs (PWID), drug injecting follows a dynamic process characterized by transitions in and out of injecting. The objective of this investigation was to examine injecting cessation episodes of 1-3-month duration as predictors of hepatitis C virus (HCV) acquisition.

DESIGN

Cohort study.

SETTING

Montréal, Canada.

PARTICIPANTS

A total of 372 HCV-uninfected (HCV RNA-negative, HCV antibody-positive or -negative) PWID (mean age = 39.3 years, 82% male, 45% HCV antibody-positive) enrolled between March 2011 and June 2016.

MEASUREMENTS

At 3-month intervals, participants completed an interviewer-administered questionnaire and were tested for HCV particles (HCV RNA). At each visit, participants indicated whether they injected in each of the past 3 months (defined as three consecutive 30-day periods). Injecting cessation patterns were evaluated on a categorical scale: persistent injecting (no injecting cessation in the past 3 months), sporadic injecting cessation (injecting cessation in 1 of 3 or 2 of 3 months) and short injecting cessation (injecting cessation in 3 of 3 months). Their association with HCV infection risk was examined using Cox regression analyses with time-dependent covariates, including age, gender, incarceration, opioid agonist treatment and other addiction treatments.

FINDINGS

At baseline, 61, 26 and 13% of participants reported persistent injecting, sporadic injecting cessation and short injecting cessation, respectively. HCV incidence was 7.5 per 100 person-years [95% confidence interval (CI) = 5.9-9.5; 916 person-years of follow-up]. In adjusted Cox models, sporadic injecting cessation and short injecting cessation were associated with lower risks of incident HCV infection compared to persistent injecting (adjusted hazard ratios = 0.56, 95% CI = 0.30-1.04 and 0.24, 95% CI = 0.09-0.61), respectively.

CONCLUSION

Short and sporadic injecting cessation episodes were common among a cohort of people who inject drugs in Montréal, Canada. Injecting cessation episodes appear to be protective against hepatitis C virus acquisition, particularly when maintained for at least 3 months.

Incarceration history and risk of HIV and hepatitis C virus acquisition among people who inject drugs: a systematic review and meta-analysis

BACKGROUND

People who inject drugs (PWID) experience a high prevalence of incarceration and might be at high risk of HIV and hepatitis C virus (HCV) infection during or after incarceration. We aimed to assess whether incarceration history elevates HIV or HCV acquisition risk among PWID.

METHODS

In this systematic review and meta-analysis, we searched MEDLINE, Embase, and PsycINFO databases for studies in any language published from Jan 1, 2000 until June 13, 2017 assessing HIV or HCV incidence among PWID. We included studies that measured HIV or HCV incidence among community-recruited PWID. We included only studies reporting original results and excluded studies that evaluated incident infections by self-report. We contacted authors of cohort studies that met the inclusion or exclusion criteria, but that did not report on the outcomes of interest, to request data. We extracted and pooled data from the included studies using random-effects meta-analyses to quantify the associations between recent (past 3, 6, or 12 months or since last follow-up) or past incarceration and HIV or HCV acquisition (primary infection or reinfection) risk among PWID. We assessed the risk of bias of included studies using the Newcastle-Ottawa Scale. Between-study heterogeneity was evaluated using the I2 statistic and the P-value for heterogeneity.

FINDINGS

We included published results from 20 studies and unpublished results from 21 studies. These studies originated from Australasia, western and eastern Europe, North and Latin America, and east and southeast Asia. Recent incarceration was associated with an 81% (relative risk [RR] 1·81, 95% CI 1·40-2·34) increase in HIV acquisition risk, with moderate heterogeneity between studies (I2=63·5%; p=0·001), and a 62% (RR 1·62, 95% CI 1·28-2·05) increase in HCV acquisition risk, also with moderate heterogeneity between studies (I2=57·3%; p=0·002). Past incarceration was associated with a 25% increase in HIV (RR 1·25, 95% CI 0·94-1·65) and a 21% increase in HCV (1·21, 1·02-1·43) acquisition risk.

INTERPRETATION

Incarceration is associated with substantial short-term increases in HIV and HCV acquisition risk among PWID and could be a significant driver of HCV and HIV transmission among PWID. These findings support the need for developing novel interventions to minimise the risk of HCV and HIV acquisition, including addressing structural risks associated with drug laws and excessive incarceration of PWID.

FUNDING

Engineering and Physical Sciences Research Council, National Institute for Health Research, National Institutes of Health.

Pharmaceutical opioid use among oral and intravenous users in Australia: A qualitative comparative study

BACKGROUND

Between 1992 and 2012 dispensing episodes for pharmaceutical opioids (PO) in Australia increased from 500000 to 7500000. In the US, increases in the prescription of PO have been linked to increases in opioid-related morbidity and mortality and transitions to heroin injection. However, Australian data indicate that morbidity and mortality related to PO are relatively low, particularly when compared to heroin and other drugs. This paper explores the characteristics and patterns of non-medical pharmaceutical opioid (NMPO) use among a sample of young people in Sydney, Australia.

METHODS

During 2015, we conducted in-depth qualitative interviews with 34 young people who use PO non-medically by oral (n=22) and intravenous (n=12) routes of administration.

RESULTS

Oral NMPO users were a more affluent group who clustered around the Northern, Inner and Eastern suburbs of Sydney, while the intravenous users came from a range of locations including rural/regional areas of NSW and socioeconomically disadvantaged suburbs of South Western Sydney. Oral users were characterised by intermittent and largely self-limiting NMPO use and reported few health and social consequences. Intravenous users reported heavy and frequent drug, including NMPO, use and a range of adverse health and social consequences including overdose, injecting risk behaviour, hepatitis C virus (HCV) infection and residential instability.

CONCLUSION

Results highlight the significance of social and structural factors in trajectories of opioid use and related harms. Factors such as stable housing and family relationships, disposable income and close social networks observed in young oral NMPO users may help to explain differences in patterns of NMPO use and related outcomes between the two groups.

Initiation into prescription opioid injection and associated trends in heroin use among people who use illicit drugs

OBJECTIVES

Prescription opioid (PO) injection among people who use illicit drugs (PWUD) is an ongoing concern, yet little is known about drug use trajectories associated with initiating PO injection, including potential associations with heroin use. This study aimed to identify predictors of PO injection initiation among PWUD, and examine trends in heroin use before and after initiating PO injection.

METHODS

Data were merged from three cohorts of PWUD recruited between September 2005 and November 2015. Predictors of PO injection initiation were identified using extended Cox regression models. Trends in heroin use pre- and post-initiation were examined with McNemar's test and compared to matched controls with linear growth curve models.

RESULTS

Among 1580 participants, 247 initiated PO injection yielding an incidence density of 3.9 (95% Confidence Interval [CI]: 3.4-4.4) per 100 person-years. In a multivariable analysis, independent predictors of PO injection initiation included heroin injection (Adjusted Hazard Ratio [AHR]=4.39, 95% CI: 3.24-5.95) and non-injection PO use (AHR=1.99, 95% CI: 1.25-3.17). In a sub-analysis, compared to matched controls, PO injection corresponded with elevated heroin use post-initiation (p≤0.05).

DISCUSSION

In this study, heroin use and non-injection PO use strongly predicted PO injection initiation. Those who initiated PO injecting had elevated heroin use patterns post-initiation compared to controls. These findings suggest that transitioning to PO injection does not appear to be a substitute for heroin use among PWUD. These findings highlight the importance of addressing PO injection in harm reduction and treatment settings.

Commentary on Sacks-Davis et al. (2016): Quantifying the risk environment-effect modification and precision population health

Substance use epidemiology focuses increasingly on the risk environment; however, few studies quantify the differential impacts of physical, social and structural environments on population health risk factors and outcomes. To do so, researchers studying the effects of the risk environment on drug-related harms should consider effect modification analyses.