Prevalence and correlates of multiple non-fatal opioid overdoses among people who inject drugs who utilise needle syringe programs in Australia

Associations among drug acquisition and use behaviors, psychosocial attributes, and opioid-involved overdoses

AIMS

This study sought to develop and assess an exploratory model of how demographic and psychosocial attributes, and drug use or acquisition behaviors interact to affect opioid-involved overdoses.

DESIGN

We conducted exploratory and confirmatory factor analysis (EFA/CFA) to identify a factor structure for ten drug acquisition and use behaviors. We then evaluated alternative structural equation models incorporating the identified factors, adding demographic and psychosocial attributes as predictors of past-year opioid overdose.

SETTING AND PARTICIPANTS

We used interview data collected for two studies recruiting opioid-misusing participants receiving services from a community-based syringe services program. The first investigated current attitudes toward drug-checking (N = 150). The second was an RCT assessing a telehealth versus in-person medical appointment for opioid use disorder treatment referral (N = 270).

MEASUREMENTS

Demographics included gender, age, race/ethnicity, education, and socioeconomic status. Psychosocial measures were homelessness, psychological distress, and trauma. Self-reported drug-related risk behaviors included using alone, having a new supplier, using opioids with benzodiazepines/alcohol, and preferring fentanyl. Past-year opioid-involved overdoses were dichotomized into experiencing none or any.

FINDINGS

The EFA/CFA revealed a two-factor structure with one factor reflecting drug acquisition and the second drug use behaviors. The selected model (CFI = .984, TLI = .981, RMSEA = .024) accounted for 13.1% of overdose probability variance. A latent variable representing psychosocial attributes was indirectly associated with an increase in past-year overdose probability (β = .234, p = .001), as mediated by the EFA/CFA identified latent variables: drug acquisition (β = .683, p < .001) and drug use (β = .567, p = .001). Drug use behaviors (β = .287, p = .04) but not drug acquisition (β = .105, p = .461) also had a significant, positive direct effect on past-year overdose. No demographic attributes were significant direct or indirect overdose predictors.

CONCLUSIONS

Psychosocial attributes, particularly homelessness, increase the probability of an overdose through associations with risky drug acquisition and drug-using behaviors. Further research is needed to replicate these findings with populations at high-risk of an opioid-related overdose to assess generalizability and refine the metrics used to assess psychosocial characteristics.

Correlates of overdose among 2711 people who use drugs and live in 7 rural US sites

BACKGROUND

Overdose rates in rural areas have been increasing globally, with large increases in the United States. Few studies, however, have identified correlates of non-fatal overdose among rural people who use drugs (PWUD). The present analysis describes correlates of nonfatal overdose among a large multistate sample of rural PWUD.

METHODS

This is a cross-sectional analysis of data gathered via surveys with PWUD recruited through seven Rural Opioid Initiative (ROI) sites. Descriptive analyses were conducted to assess the prevalence of past 30-day overdose. Generalized estimating equations were used to estimate a series of multivariable models quantifying relationships of select factors to past-month overdose; factors were selected using the Risk Environment Framework.

RESULTS

The multisite sample included 2711 PWUD, 6% of whom reported overdosing in the past 30 days. In the fully adjusted model, houselessness (AOR=2.27, 95%CI[1.48, 3.48]), a positive test result for Hepatitis C infection (AOR=1.73 95%CI[1.18, 2.52]) and heroin/fentanyl use (AOR= 8.58 95%CI [3.01, 24.50]) were associated with an increased risk of reporting past 30-day overdose, while having a high-school education or less was associated with reduced odds of overdose (AOR=0.52, 95% CI[0.37, 0.74]).

CONCLUSION

As in urban areas, houselessness, Hepatitis C infection, and the use of heroin and fentanyl were significant correlates of overdose. Widespread access to overdose prevention interventions - including fentanyl test strips and naloxone - is critical in this rural context, with particular outreach needed to unhoused populations, people living with Hepatitis C, and people using opioids.

A descriptive coronial study of heroin toxicity deaths in Australia, 2020-2022: Characteristics, toxicology and survival times

BACKGROUND AND AIMS

Mortality rates among people who use heroin are estimated to be 15 times that of the general population. The study aimed to determine (1) the case characteristics and circumstances of death of heroin-related toxicity deaths in Australia, 2020-2022; (2) their toxicological profile and major autopsy findings; (3) the proportion of cases in which blood 6-acetyl morphine (6AM) was detected, as a proxy measure of survival times; and (4) compare 6AM positive and negative cases on toxicology, circumstances of death and acute clinical presentation.

DESIGN

Retrospective study of heroin toxicity deaths in Australia, 2020-2022, retrieved from the National Coronial Information System.

SETTING

This study was conducted Australia-wide.

CASES

There were 610 cases of fatal heroin-related drug toxicity.

MEASUREMENTS

Information was collected on characteristics, manner of death, toxicology and autopsy results.

FINDINGS

The mean age was 42.6 years (range 18-73 years), 80.5% were male and 7.5% were enrolled in a drug treatment programme. The circumstances of death were as follows: unintentional drug toxicity (86.2%), combined unintentional drug toxicity/disease (11.3%) and intentional drug toxicity (2.5%). The median free morphine concentration was 0.17 mg/L (range 0.00-4.20 mg/L). Psychoactive drugs other than heroin were present in 95.2% (Confidence Interval 93.1%-96.8%), most commonly hypnosedatives (62.3%, 58.2%-66.4%) and psychostimulants (44.8%, 40.7%-49.1%). Major autopsy findings of clinical significance included acute bronchopneumonia (14.8%, 11.3%-18.8%), emphysema (16.9%, 13.2%-21.1%), cardiomegaly (30.1%, 12.7%-28.2%), coronary artery disease (27.4%, 23.0%-32.3%), coronary replacement fibrosis (13.4%, 10.1%-17.3%), hepatic cirrhosis (8.8%, 6.6%-12.2%) and renal fibrosis (10.3%, 7.3%-14.0%). In 47.0% (42.3%-51.2%), 6AM was present in blood.

CONCLUSIONS

The 'typical' heroin overdose case in Australia from 2020 to 2022 was a male who injected heroin, aged in the 40s, not enrolled in a treatment programme and had used multiple drugs. In over half of cases, there had been a sufficient survival time for 6-acetyl morphine to have been metabolised, which may indicate times in excess of 20-30 min.

Associations among Drug Acquisition and Use Behaviors, Psychosocial Attributes, and Opioid-Involved Overdoses: A SEM Analysis

Aims

This study sought to develop and assess an exploratory model of how demographic and psychosocial attributes, and drug use or acquisition behaviors interact to affect opioid-involved overdoses.

Methods

We conducted exploratory and confirmatory factor analysis (EFA/CFA) to identify a factor structure for ten drug acquisition and use behaviors. We then evaluated alternative structural equation models incorporating the identified factors, adding demographic and psychosocial attributes as predictors of past-year opioid overdose. We used interview data collected for two studies recruiting opioid-misusing participants receiving services from a community-based syringe service program. The first investigated current attitudes toward drug-checking (N = 150). The second was an RCT assessing a telehealth versus in-person medical appointment for opioid use disorder treatment referral (N = 270). Demographics included gender, age, race/ethnicity, education, and socioeconomic status. Psychosocial measures were homelessness, psychological distress, and trauma. Self-reported drug-related risk behaviors included using alone, having a new supplier, using opioids with benzodiazepines/alcohol, and preferring fentanyl. Past-year opioid-involved overdoses were dichotomized into experiencing none or any.

Results

The EFA/CFA revealed a two-factor structure with one factor reflecting drug acquisition and the second drug use behaviors. The selected model (CFI = .984, TLI = .981, RMSEA = .024) accounted for 13.1% of overdose probability variance. A latent variable representing psychosocial attributes was indirectly associated with an increase in past-year overdose probability (β=.234, p = .001), as mediated by the EFA/CFA identified latent variables: drug acquisition (β=.683, p < .001) and drug use (β=.567, p = .001). Drug use behaviors (β=.287, p = .04) but not drug acquisition (β=.105, p = .461) also had a significant, positive direct effect on past-year overdose. No demographic attributes were significant direct or indirect overdose predictors.

Conclusions

Psychosocial attributes, particularly homelessness, increase the probability of an overdose through associations with risky drug acquisition and drug-using behaviors. To increase effectiveness, prevention efforts might address the interacting overdose risks that span multiple functional domains.

Comprehensive needle and syringe program and opioid agonist therapy reduce HIV and hepatitis c virus acquisition among people who inject drugs in different settings: A pooled analysis of emulated trials

BACKGROUND AND AIMS

Although the Netherlands, Canada and Australia were early adopters of harm reduction for people who inject drugs (PWID), their respective HIV and hepatitis C (HCV) epidemics differ. We measured the pooled effect of needle and syringe program (NSP) and opioid agonist therapy (OAT) participation on HIV and HCV incidence in these settings.

DESIGN

For each cohort, we emulated the design and statistical analysis of a target trial using observational data.

SETTING AND PARTICIPANTS

We included PWID at risk of HIV or HCV infection from the Amsterdam Cohort Studies (1985-2013), Vancouver Injection Drug Users Study (1997-2009) and Melbourne Injecting Drug User Cohort Study (SuperMIX) (2010-2021).

MEASUREMENTS

Separately for each infection and cohort (only HCV in SuperMIX), marginal structural models were used to compare the effect of comprehensive (on OAT and 100% NSP coverage or on OAT only if no recent injection drug use) versus no/partial NSP/OAT (no OAT and/or <100% NSP coverage) participation. Pooled hazard ratios (HR) and 95% CI were calculated using random-effects meta-analysis.

FINDINGS

We observed 94 HIV seroconversions and 81 HCV seroconversions among 2023 and 430 participants, respectively. Comprehensive NSP/OAT led to a 41% lower risk of HIV acquisition (pooled HR = 0.59, 95% CI = 0.36-0.96) and a 76% lower risk of HCV acquisition (pooled HR = 0.24, 95% CI = 0.11-0.51), compared with no/partial NSP/OAT, with little heterogeneity between studies for both infections (I2  = 0%).

CONCLUSIONS

In the Netherlands, Canada and Australia, comprehensive needle and syringe program and opioid agonist therapy participation appears to substantially reduce HIV and hepatitis C acquisition compared with no or partial needle and syringe program/opioid agonist therapy participation. These findings from an emulated trial design reinforce the critical role of comprehensive access to harm reduction in optimizing infection prevention for people who inject drugs.

Overdose and suicide are different phenomena among opioid users that require different clinical management

Given the high rates of mental health comorbidity among opioid users, and increasing rates of opioid prescription for chronic pain, psychiatrists and mental health clinicians are likely to treat patients who are dependent on opioids. Among such patients, many will have histories of opioid overdose or suicide attempts. It is tempting to assume that these are related behaviours and that 'accidental' overdoses are actually suicide attempts. We provide evidence here to demonstrate that while some overdoses are intentional, most are not. More than half of deaths among opioid users are due to unintentional overdose. Suicides constitute a minority: less than 10% of heroin user deaths are estimated to be due to suicide, as are 20-30% of prescribed opioid fatalities. Moreover, suicide attempts are more commonly made using means other than opioids. Overdose and suicide among opioid dependent patients are two distinct phenomena, associated with different risk factors, that need to be separately assessed and their respective risk managed.