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A screenshot copy of the simulation model that describes the spread of HIV among PWID. Each injecting network can be high or low risk in terms of frequency of syringe sharing (large pink or yellow squares) and using HDS or LDS syringes (small pink or yellow squares inside the large squares).
Source publication
Background and aims
Using mathematical modeling to illustrate and predict how different heroin source-forms: “black tar” (BTH) and powder heroin (PH) can affect HIV transmission in the context of contrasting injecting practices. By quantifying HIV risk by these two heroin source-types we show how each affects the incidence and prevalence of HIV ove...
Context in source publication
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Background: People who smoke drugs (PWSD) are at high risk of both infectious disease and overdose. Harm reduction activities organised by their peers in the community can reduce risk by providing education; safer smoking supplies, and facilitate access to other services. Peers also provide a network of people who provide social support to PWSD whi...
Background:
People who use drugs (PWUD) are at high risk for COVID-19 infection, morbidity, and mortality. COVID-19 vaccines are safe and effective at reducing serious illness and death from COVID-19. There are sparse data on the perceptions and willingness of PWUD to receive COVID-19 vaccination.
Materials and methods:
In order to assess the pe...
Background
British Columbia (BC) is in the midst of an opioid overdose crisis. Since 2017, smoking illicit drugs has been the leading mode of drug administration causing overdose death. Yet, little is known about people who smoke opioids, and factors underlying choice of mode of administration. The study objectives are to identify the prevalence an...
Background
Approaches to address unmet mental health care needs in supportive housing settings are needed. Collaborative approaches to delivering psychiatric care have robust evidence in multiple settings, however such approaches have not been adequately studied in housing settings. This study evaluates the implementation of a shifted outpatient co...
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-...
Citations
... 3,7,14,[17][18][19][20][21] Researchers are embracing simulation models to generate insights about a range of substancerelated topics (e.g., substance use laws and regulations, social networks, economics). 16,[22][23][24][25][26][27][28] However, these models are often highly complex and use many idiosyncratic parameters and assumptions to examine specific circumstances. Consequently, the growing subfield of substance use simulation will have difficulty collaborating and building cumulative progress. ...
Background: Substance use behaviors and their etiologies are complex and often not amenable to traditional statistical analysis. Computational models are an increasingly popular alternative approach for investigating substance use. However, cumulative progress has been difficult because of a lack of standardization. This study aims to develop and evaluate a simple computational model that could serve as a common starting point for future computation-based investigations of substance use.
Methods: A two-state ("Using" a substance or "Not using" a substance) stochastic model with three manipulable parameters is used to reproduce the distributions of past 30-day alcohol, cannabis, and tobacco cigarette consumption frequencies (e.g., used on 5 days within the past 30 days) observed in the U.S. National Survey on Drug Use and Health (NSDUH) (years 2002-2019 combined). The model employs a path-dependent process: during each iteration (i.e., each "day") of the simulation, each computational object chooses to use or not use a substance based on probabilities that are contingent on choices made in prior iterations. The Lempel-Ziv complexity measure was used to examine the resulting sequences of binary decisions (use or don't use) made by each computational object.
Results: The model accurately reproduces the population-level "U-shaped" distributions of past 30-day alcohol, cannabis, and cigarette use in the U.S. The path dependence function was required for reproducing these distributions. The model also suggests an "arc" of behavioral complexity stages: as the frequency of use increases, the complexity of decision sequences increases, peaks, and then decreases. However, decision sequence complexity still varied considerably among objects with similar frequencies of use.
Conclusion: A simple computational model that simulates individual-level sequences of substance use can reproduce the population-level distributions of substance use observed in national survey data. The model also suggests that complexity measures are a potentially helpful tool for examining substance use behaviors.
... urban or rural) when more information about specific structures is known. In model development, we leveraged our past experience with ABMs that simulated HIV transmission among PWID (though none of these prior studies was specific to HIV among PWID in New York City) (Zule and Bobashev, 2009;Zule et al., 2018;Bobashev et al., 2010Bobashev et al., , 2019Bobashev et al., 2019;Bobashev and Zule, 2010). ...
... urban or rural) when more information about specific structures is known. In model development, we leveraged our past experience with ABMs that simulated HIV transmission among PWID (though none of these prior studies was specific to HIV among PWID in New York City) (Zule and Bobashev, 2009;Zule et al., 2018;Bobashev et al., 2010Bobashev et al., , 2019Bobashev et al., 2019;Bobashev and Zule, 2010). ...
... Outbreak in Scott County, IN in 2014) (Broz et al., 2018). We follow Zule et al., (2009Zule et al., ( , 2018 (Zule and Bobashev, 2009;Zule et al., 2018) and Bobashev et al., (2010Bobashev et al., ( , 2019 (Bobashev et al., 2019;Bobashev and Zule, 2010) and consider estimates of HIV transmission per shared injection after an HIV-infected not on ART person being p = 0.00008. 11. ...
Background
We explore injecting risk and HIV incidence among PWID in New York City (NYC), from 2012-2019, when incidence was extremely low, <0.1/100 person-years at risk, and during disruption of prevention services due to the COVID-19 pandemic.
Methods
We developed an Agent-Based model (ABM) to simulate sharing injecting equipment and measure HIV incidence in NYC. The model was adapted from a previous ABM model developed to compare HIV transmission with “high” versus “low” dead space syringes. Data for applying the model to NYC during the period of very low HIV incidence was taken from the “Risk Factors” study, a long-running study of participants entering substance use treatment in NYC. Injecting risk behavior had not been eliminated in this population, with approximately 15% reported recent syringe sharing. Data for possible transmission during COVID-19 disruption was taken from previous HIV outbreaks and early studies of the pandemic in NYC.
Results
The modeled incidence rates fell within the 95% confidence bounds of all of the empirically observed incidence rates, without any additional calibration of the model. Potential COVID-19 disruptions increased the probability of an outbreak from 0.03 to 0.25.
Conclusions
The primary factors in the very low HIV incidence were the extremely small numbers of PWID likely to transmit HIV and that most sharing occurs within small, relatively stable, mostly seroconcordant groups. Containing an HIV outbreak among PWID during a continuing pandemic would be quite difficult. Pre-pandemic levels of HIV prevention services should be restored as quickly as feasible.
... While fatal overdose represents a "worst possible" outcome of substance use, these overdose trends foreshadow impacts on morbidity that could occur years into the future. For example, the replacement of black tar heroin with fentanyl has been associated with increased risks for HCV and HIV infection, due to increased injection frequency and differences in drug preparation Bobashev et al., 2019). Additionally, non-fatal overdoses are associated with substantial morbidity and increased risk of mortality (Warner-Smith et al., 2002;Weiner et al., 2020). ...
As overdose mortality is spiking during the COVID-19 pandemic, few race/ethnicity-stratified trends are available. This is of particular concern as overdose mortality was increasing most rapidly in Black and Latinx communities prior to the pandemic. We used quarterly, age-standardized overdose mortality rates from California to assess trends by race/ethnicity and drug involved over time. Rates from 2020 Q2-Q4 were compared to expected trends based on ARIMA forecasting models fit using data from 2006 to 2020 Q1. In 2020 Q2-Q4 overdose death rates rose by 49.8% from 2019, exceeding an expected increase of 11.5% (95%CI: 0.5%–22.5%). Rates significantly exceeded forecasted trends for all racial/ethnic groups. Black/African American individuals saw an increase of 52.4% from 2019, compared to 42.6% among their White counterparts. The absolute Black-White overdose mortality gap rose from 0.7 higher per 100,000 for Black individuals in 2018 to 4.8 in 2019, and further increased to 9.9 during the pandemic. Black overdose mortality in California was therefore 34.3% higher than that of White individuals in 2020 Q2-Q4. This reflects growing methamphetamine-, cocaine-, and fentanyl-involved deaths among Black communities. Growing racial disparities in overdose must be understood in the context of the unequal social and economic fallout from the COVID-19 pandemic, during which time Black communities have been subjected to the dual burden of disproportionate COVID-19 deaths and rising overdose mortality. Increased investments are required to ameliorate racial/ethnic disparities in substance use treatment, harm reduction, and the structural drivers of overdose, as part of the COVID-19 response and post-pandemic recovery efforts.
... Ciccarone and Bourgois [53] present a hypothesis that cold water heroin solutions may have fostered HIV transmission in the early phases of the epidemic in the USA. More recently, a model of HIV transmission examining heroin source-type (including cold water prepared solutions) supports this prior hypothesis [54]. Gaskin et al. [55] present one of the few studies with a HCV transmission remit to detail water source. ...
Background:
The United Kingdom is experiencing an increase in drug-related deaths and serious bacterial infections among its most vulnerable citizens. Cuts to essential services, coupled with a growing homeless population, create a challenging environment to tackle this public health crisis. In this paper, we highlight an underexplored environmental constraint faced by people living and injecting drugs on the streets. Access to water for injection is restricted in the UK, due to legislative and financial barriers. Austerity measures, such as public toilet closures, further restrict the ability of people made homeless to access clean water and protect themselves from health harms.
Methods:
We generated questionnaire (n = 455) and in-depth qualitative interview (n = 32) data with people who inject drugs in London for the Care and Prevent study. Participants provided detail on their life history; drug use, injecting and living environments; health conditions and care seeking practices.
Findings:
A high proportion of the survey sample reported lifetime history of street homelessness (78%), bacterial infections (65%) and related hospitalisation (30%). Qualitative accounts highlight unsafe, potentially dangerous, injection practices in semi-public spaces. Multiple constraints to sourcing sterile water for injection preparation were reported. Alternatives to sterile water included puddle water, toilet cistern water, whisky, cola soda and saliva. Participants who injected heroin and crack cocaine together unanimously reported adding water at two stages during injection preparation: first, adding water as a vehicle for heroin (which was then heated); second, adding cold water to the heroin mixture prior to adding the crack cocaine. This new finding of a stage addition of solvent may represent an additional risk of infection.
Conclusion:
Currently, harm reduction equipment and resources for safe injecting are not meeting the needs of people who inject drugs who are street homeless or unstably housed. Preparation of injections with non-sterile water sources could precipitate bacterial and fungal infections, particularly when used without the application of heat. It is crucial that water for injection, also skin cleaning, is made available for the unstably housed and that harm reduction messaging is tailored to speak to the everyday realities of people who prepare and inject drugs in public spaces.
Background
Illicitly-manufactured fentanyls (fentanyl) have changed the risk environment of people who use drugs (PWUD). In California and many western US states, the opioid overdose rate spiked from 2016 to 2021, driven largely by fentanyl. Mexican border cities act as transit through-points for the illicit drug supply and similar evolving health risks are likely to be present. Nevertheless, due to data gaps in surveillance infrastructure, little is known about fentanyl prevalence in Mexico.
Methods
We employ intensive ethnographic participant-observation among PWUD, as well as key informants including harm reduction professionals, EMTs, and physicians on the front lines in Tijuana, Mexico. We triangulate interview data and direct observations of consumption practices with n=652 immunoassay-based fentanyl tests of drug paraphernalia from mobile harm reduction clinics in various points throughout the city.
Results
PWUD informants described a sharp increase in the psychoactive potency and availability of powder heroin—referred to as “china white”—and concomitant increases in frequency of overdose, soft tissue infection, and polysubstance methamphetamine use. Fentanyl positivity was found among 52.8% (95%CI: 48.9–56.6%) of syringes collected at harm reduction spaces, and varied strongly across sites, from 2.7% (0.0–5.7%) to 76.5% (68.2–84.7%), implying strong market heterogeneity. Controlling for location of collection, syringe-based fentanyl positivity increased by 21.7% (10.1–42.3%) during eight months of testing. Key informants confirm numerous increased public health risks from fentanyl and describe the absence of a systematic or evidence-based governmental response; naloxone remains difficult to access and recent austerity measures have cut funding for harm reduction in Mexico.
Conclusions
Fentanyl, linked to powder heroin, is changing the risk environment of PWUD on the US–Mexico border. Improved surveillance is needed to track the evolving street drug supply in Mexico and related health impacts for vulnerable populations. Structural factors limiting access to naloxone, harm reduction, substance use treatment, and healthcare, and minimal overdose surveillance, must be improved to provide an effective systemic response.
The opioid crisis in the United States (US) has been defined by waves of drug- and locality-specific Opioid use-Related Epidemics (OREs) of overdose and bloodborne infections, among a range of health harms. The ability to identify localities at risk of such OREs, and better yet, to predict which ones will experience them, holds the potential to mitigate further morbidity and mortality. This narrative review was conducted to identify and describe quantitative approaches aimed at the “risk assessment”, “detection” or “prediction” of OREs in the US. We implemented a PubMed search composed of the: 1) objective (e.g. prediction), 2) epidemiologic outcome (e.g. outbreak), 3) underlying cause (i.e. opioid use), 4) health outcome (e.g. overdose, HIV), 5) location (i.e. U.S.). In total, 46 studies were included, and the following information extracted: discipline, objective, health outcome, drug/substance type, geographic region/unit of analysis, and data sources. Studies identified relied on clinical, epidemiological, behavioral and drug markets surveillance and applied a range of methods including statistical regression, geospatial analyses, dynamic modeling, phylogenetic analyses and machine learning. Studies for the prediction of overdose mortality at national/state/county and zip code level are rapidly emerging. Geospatial methods are increasingly used to identify hotspots of opioid use and overdose. In the context of infectious disease OREs, routine genetic sequencing of patient samples to identify growing transmission clusters via phylogenetic methods could increase early detection capacity. A coordinated implementation of multiple, complementary approaches would increase our ability to successfully anticipate outbreak risk and respond preemptively. We present a multi-disciplinary framework for the prediction of OREs in the US and reflect on challenges research teams will face in implementing such strategies along with good practices.
