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

Illicit Fentanyl Use and Hepatitis C Virus Seroconversion Among People Who Inject Drugs in Tijuana and San Diego: Results From a Binational Cohort Study

BACKGROUND

Illicitly manufactured fentanyl (IMF) increases overdose mortality, but its role in infectious disease transmission is unknown. We examined whether IMF use predicts hepatitis C virus (HCV) and human immunodeficiency virus (HIV) incidence among a cohort of people who inject drugs (PWID) in San Diego, California and Tijuana, Mexico.

METHODS

PWID were recruited during 2020-2022, undergoing semi-annual interviewer-administered surveys and HIV and HCV serological rapid tests through 2024. Cox regression was conducted to examine predictors of seroconversion considering self-reported IMF use as a 6-month lagged, time-dependent covariate.

RESULTS

Of 398 PWID at baseline, 67% resided in San Diego, 70% were male, median age was 43 years, 42% reported receptive needle sharing, and 25% reported using IMF. HCV incidence was 14.26 per 100 person-years (95% confidence interval [CI]: 11.49-17.02), and HIV incidence was 1.29 (95% CI: .49-2.10). IMF was associated with HCV seroconversion, with a univariable hazard ratio (HR) of 1.64 (95% CI: 1.09-2.40), and multivariable HR of 1.57 (95% CI: 1.03-2.40). The direction of the relationship with HIV was similar, albeit not significant (HR 2.39; 95% CI: .66-8.64).

CONCLUSIONS

We document a novel association between IMF and HCV seroconversion among PWID in Tijuana-San Diego. Few HIV seroconversions (n = 10) precluded our ability to assess if a similar relationship held for HIV. IMF's short half-life may destabilize PWID-increasing the need for repeat dosing and sharing smoking materials and syringes. New preventive care approaches may reduce HCV transmission in the fentanyl era.

Effects of Beta Lactams on Behavioral Outcomes of Substance Use Disorders: A Meta-Analysis of Preclinical Studies

INTRODUCTION

Preclinical studies demonstrated that beta-lactams have neuroprotective effects in conditions involving glutamate neuroexcitotoxicity, including substance use disorders (SUDs). This meta-analysis aims to analyze the existing evidences on the effects of beta-lactams as glutamate transporter 1 (GLT-1) upregulators in animal models of SUDs, identification of gaps in the literature, and setting the stage for potential translation into clinical phases.

METHODS

Meta-analysis was conducted on preclinical studies retrieved systematically from MEDLINE and ScienceDirect databases. Abused substances were identified by refereeing to the National Institute on Drug Abuse (NIDA). The results were quantitatively described with a focus on the behavioral outcomes. Treatment effect sizes were described using standardized mean difference, and they were pooled using random effect model. I2-statistic was used to assess heterogeneity, and Funnel plot and Egger's test were used for assessment of publication bias.

RESULTS

Literature search yielded a total of 71 studies that were eligible to be included in the analysis. Through these studies, the effects of beta-lactams were evaluated in animal models of nicotine, cannabis, amphetamines, synthetic cathinone, opioids, ethanol, and cocaine use disorders as well as steroids-related aggressive behaviors. Meta-analysis showed that treatments with beta-lactams consistently reduced the pooled undesired effects of the abused substances in several paradigms, including drug-self administration, conditioned place preference, drug seeking behaviors, hyperlocomotion, withdrawal syndromes, tolerance to analgesic effects, hyperalgesia, and hyperthermia.

CONCLUSION

This meta-analysis revealed that enhancing GLT-1 expression in the brain through beta-lactams seemed to be a promising treatment approach in the context of substance use disorders, as indicated by results in animal models.

Centering persons who use drugs: addressing social determinants of health among patients hospitalized with substance use disorders

Social workers have emerged as leaders within Addiction Consult Services (ACS) due to their ability to provide a wide range of services, from crisis work and brief therapeutic interventions to connecting patients to community resources. Many hospitals have implemented ACS to address the overdose crisis and the sharp rise in drug use-related infections, including skin and soft tissue infections, osteomyelitis, and endocarditis; a result of unaddressed systemic social determinants of health (SDOH). Yet, despite social workers being at the forefront of inpatient substance use work, little guidance exists regarding social work's role in leading person-centered addiction care and addressing SDOH in the hospital setting. The authors of this paper are licensed clinical social workers who have worked across five different health systems, engaging persons who use drugs (PWUD) in the context of an ACS. This paper examines five practice interventions of social work practice within hospitals that represent key points for innovation. Drawing on social work's unique commitments to social justice, strengths, and person-in-environment, these interventions operate within eco-social approaches to help us grapple more effectively with ways that health - and disease - are socially and economically produced by multiple interacting factors. We provide a clinical roadmap of interventions for social workers in hospital settings with PWUD to demonstrate how social work leadership within inpatient care models can help us better address the impacts of various intersecting SDOH on the care of PWUD.

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.

Social and structural determinants of injection drug use-associated bacterial and fungal infections: A qualitative systematic review and thematic synthesis

BACKGROUND AND AIMS

Injection drug use-associated bacterial and fungal infections are increasingly common, and social contexts shape individuals' injecting practices and treatment experiences. We sought to synthesize qualitative studies of social-structural factors influencing incidence and treatment of injecting-related infections.

METHODS

We searched PubMed, EMBASE, Scopus, CINAHL and PsycINFO from 1 January 2000 to 18 February 2021. Informed by Rhodes' 'risk environment' framework, we performed thematic synthesis in three stages: (1) line-by-line coding; (2) organizing codes into descriptive themes, reflecting interpretations of study authors; and (3) consolidating descriptive themes into conceptual categories to identify higher-order analytical themes.

RESULTS

We screened 4841 abstracts and included 26 qualitative studies on experiences of injecting-related bacterial and fungal infections. We identified six descriptive themes organized into two analytical themes. The first analytical theme, social production of risk, considered macro-environmental influences. Four descriptive themes highlighted pathways through which this occurs: (1) unregulated drug supply, leading to poor drug quality and solubility; (2) unsafe spaces, influenced by policing practices and insecure housing; (3) health-care policies and practices, leading to negative experiences that discourage access to care; and (4) restrictions on harm reduction programmes, including structural barriers to effective service provision. The second analytical theme, practices of care among people who use drugs, addressed protective strategies that people employ within infection risk environments. Associated descriptive themes were: (5) mutual care, including assisted-injecting and sharing sterile equipment; and (6) self-care, including vein health and self-treatment. Within constraining risk environments, some protective strategies for bacterial infections precipitated other health risks (e.g. HIV transmission).

CONCLUSIONS

Injecting-related bacterial and fungal infections are shaped by modifiable social-structural factors, including poor quality unregulated drugs, criminalization and policing enforcement, insufficient housing, limited harm reduction services and harmful health-care practices. People who inject drugs navigate these barriers while attempting to protect themselves and their community.

Prevalence and factors associated with neck injection among people who inject drugs in San Francisco, California

BACKGROUND

Groin and neck injections are generally a last resort for people who inject drugs (PWID) who do not have easy access to functioning veins. These alternative injection practices can lead to an increased likelihood of adverse health outcomes. There is still much we do not know about groin and neck injections among PWID in the US, as the literature to-date comes from studies primarily focused on groin injections outside the US. We assessed prevalence, predictors, and associated behaviors of neck injection through a survey fielded in San Francisco, California, US.

METHODS

The sample comes from a longitudinal observational study that used targeted sampling to recruit PWID in San Francisco. The current study sample includes 239 PWID who completed their 12-month survey between June 2019 and June 2020.

RESULTS

About a third of the sample reported injecting in their neck in the past 30 days, with the most common reason being lack of available veins. Age, past 6-month abscess / soft tissue infection, and past 30-day use of opioids mixed with cocaine were significantly associated with past 30-day neck injection in the final multivariate model. Past 30-day neck injection was also significantly associated with being injected by another person in the past 30 days.

CONCLUSIONS

PWID at higher risk for vein deterioration were more likely to inject into their neck. Harm reduction strategies such as safer injection counseling, safe smoking supplies, use of "street doctors," and safe consumption sites may reduce instances of neck injection and/or associated health risks.

Improving Harm Reduction Services: A Qualitative Study on the Perspectives of Highly Marginalized Persons Who Inject Drugs in Montreal

Harm reduction (HR) is an alternative to the moralization of drug use and a pragmatic public health approach aimed at minimizing harms associated with use. This study sought to gain the perspectives of persons who inject drugs (PWID) on the adequacy of services provided by HR organizations in Montreal. Twenty-two semi-structured interviews and two focus groups were conducted with 30 participants. Some of the key advantages of HR perceived by participants include access to injection equipment, psychosocial support, and reduced social isolation. However, many wanted more opportunities for social insertion and greater value to be placed on their knowledge and life experiences (e.g., experiential knowledge of the street scene, drug use, sex work, or homelessness). This study suggests that PWID who access HR services in Montreal are interested in paid work opportunities in environments that promote power sharing, and activities that are conducted and managed by and for them.

The impact of opioid agonist treatment on hospitalisations for injecting-related diseases among an opioid dependent population: A retrospective data linkage study

BACKGROUND

Injecting-related bacterial and fungal infections cause substantial illness and disability among people who use illicit drugs. Opioid agonist treatment (OAT) reduces injecting frequency and the transmission of blood borne viruses. We estimated the impact of OAT on hospitalisations for non-viral infections and examine trends in incidence over time.

METHODS

We conducted a retrospective cohort study using linked administrative data. The cohort included 47 163 individuals starting OAT between August 2001 and December 2017 in New South Wales, Australia, with 454 951 person-years of follow-up. The primary outcome was hospitalisation for an injecting-related disease. The primary exposure was OAT status (out of OAT, first four weeks of OAT, and OAT retention [i.e., more than four weeks in treatment]). Covariates included demographic characteristics, year of hospitalisation, and recent clinical treatment.

RESULTS

9122 participants (19.3%) had at least one hospitalisation for any injecting-related disease. Compared to time out of treatment, retention on OAT was associated with a reduced rate of injecting-related diseases (adjusted rate ratio[ARR]=0.92; 95%CI 0.87-0.97). The first four weeks of treatment was associated with an increased rate (ARR 1.53, 95%CI 1.38-1.70), which we believe is explained by referral pathways between hospital and community OAT services. The age-adjusted incidence rates of hospitalisations for any injecting-related disease increased from 34.8 (95% CI =30.2-40.0) per 1000 person-years in 2001 to 54.9 (95%CI=51.3-58.8) in 2017.

INTERPRETATION

Stable OAT is associated with reduced hospitalisations for injecting-related bacterial infections; however, OAT appears insufficient to prevent these harms as the rate of these infections is increasing in Australia.

Opioid agonist treatment and risk of death or rehospitalization following injection drug use-associated bacterial and fungal infections: A cohort study in New South Wales, Australia

BACKGROUND

Injecting-related bacterial and fungal infections are associated with significant morbidity and mortality among people who inject drugs (PWID), and they are increasing in incidence. Following hospitalization with an injecting-related infection, use of opioid agonist treatment (OAT; methadone or buprenorphine) may be associated with reduced risk of death or rehospitalization with an injecting-related infection.

METHODS AND FINDINGS

Data came from the Opioid Agonist Treatment Safety (OATS) study, an administrative linkage cohort including all people in New South Wales, Australia, who accessed OAT between July 1, 2001 and June 28, 2018. Included participants survived a hospitalization with injecting-related infections (i.e., skin and soft-tissue infection, sepsis/bacteremia, endocarditis, osteomyelitis, septic arthritis, or epidural/brain abscess). Outcomes were all-cause death and rehospitalization for injecting-related infections. OAT exposure was classified as time varying by days on or off treatment, following hospital discharge. We used separate Cox proportional hazards models to assess associations between each outcome and OAT exposure. The study included 8,943 participants (mean age 39 years, standard deviation [SD] 11 years; 34% women). The most common infections during participants' index hospitalizations were skin and soft tissue (7,021; 79%), sepsis/bacteremia (1,207; 14%), and endocarditis (431; 5%). During median 6.56 years follow-up, 1,481 (17%) participants died; use of OAT was associated with lower hazard of death (adjusted hazard ratio [aHR] 0.63, 95% confidence interval [CI] 0.57 to 0.70). During median 3.41 years follow-up, 3,653 (41%) were rehospitalized for injecting-related infections; use of OAT was associated with lower hazard of these rehospitalizations (aHR 0.89, 95% CI 0.84 to 0.96). Study limitations include the use of routinely collected administrative data, which lacks information on other risk factors for injecting-related infections including injecting practices, injection stimulant use, housing status, and access to harm reduction services (e.g., needle exchange and supervised injecting sites); we also lacked information on OAT medication dosages.

CONCLUSIONS

Following hospitalizations with injection drug use-associated bacterial and fungal infections, use of OAT is associated with lower risks of death and recurrent injecting-related infections among people with opioid use disorder.

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.