The effectiveness of abstinence-based and harm reduction-based interventions in reducing problematic substance use in adults who are experiencing homelessness in high income countries: A systematic review and meta-analysis: A systematic review

Background

Homelessness is a traumatic experience, and can have a devastating effect on those experiencing it. People who are homeless often face significant barriers when accessing public services, and have often experienced adverse childhood events, extreme social disadvantage, physical, emotional and sexual abuse, neglect, low self-esteem, poor physical and mental health, and much lower life expectancy compared to the general population. Rates of problematic substance use are disproportionately high, with many using drugs and alcohol to deal with the stress of living on the street, to keep warm, or to block out memories of previous abuse or trauma. Substance dependency can also create barriers to successful transition to stable housing.

Objectives

To understand the effectiveness of different substance use interventions for adults experiencing homelessness.

Search Methods

The primary source of studies for was the 4th edition of the Homelessness Effectiveness Studies Evidence and Gaps Maps (EGM). Searches for the EGM were completed in September 2021. Other potential studies were identified through a call for grey evidence, hand-searching key journals, and unpacking relevant systematic reviews.

Selection Criteria

Eligible studies were impact evaluations that involved some comparison group. We included studies that tested the effectiveness of substance use interventions, and measured substance use outcomes, for adults experiencing homelessness in high income countries.

Data Collection and Analysis

Descriptive characteristics and statistical information in included studies were coded and checked by at least two members of the review team. Studies selected for the review were assessed for confidence in the findings. Standardised effect sizes were calculated and, if a study did not provide sufficient raw data for the calculation of an effect size, author(s) were contacted to obtain these data. We used random-effects meta-analysis and robust-variance estimation procedures to synthesise effect sizes. If a study included multiple effects, we carried out a critical assessment to determine (even if only theoretically) whether the effects are likely to be dependent. Where dependent effects were identified, we used robust variance estimation to determine whether we can account for these. Where effect sizes were converted from a binary to continuous measure (or vice versa), we undertook a sensitivity analysis by running an additional analysis with these studies omitted. We also assessed the sensitivity of results to inclusion of non-randomised studies and studies classified as low confidence in findings. All included an assessment of statistical heterogeneity. Finally, we undertook analysis to assess whether publication bias was likely to be a factor in our findings. For those studies that we were unable to include in meta-analysis, we have provided a narrative synthesis of the study and its findings.

Main Results

We included 48 individual papers covering 34 unique studies. The studies covered 15, 255 participants, with all but one of the studies being from the United States and Canada. Most papers were rated as low confidence (n = 25, or 52%). By far the most common reason for studies being rated as low confidence was high rates of attrition and/or differential attrition of study participants, that fell below the What Works Clearinghouse liberal attrition standard. Eleven of the included studies were rated as medium confidence and 12 studies as high confidence. The interventions included in our analysis were more effective in reducing substance use than treatment as usual, with an overall effect size of -0.11 SD (95% confidence interval [CI], -0.27, 0.05). There was substantial heterogeneity across studies, and the results were sensitive to the removal of low confidence studies (-0.21 SD, 95% CI [-0.59, 0.17] - 6 studies, 17 effect sizes), the removal of quasi-experimental studies (-0.14 SD, 95% CI [-0.30, 0.02] - 14 studies, 41 effect sizes) and the removal of studies where an effect size had been converted from a binary to a continuous outcome (-0.08 SD, 95% CI [-0.31, 0.15] - 10 studies, 31 effect sizes). This suggests that the findings are sensitive to the inclusion of lower quality studies, although unusually the average effect increases when we removed low confidence studies. The average effect for abstinence-based interventions compared to treatment-as-usual (TAU) service provision was -0.28 SD (95% CI, -0.65, 0.09) (6 studies, 15 effect sizes), and for harm reduction interventions compared to a TAU service provision is close to 0 at 0.03 SD (95% CI, -0.08, 0.14) (9 studies, 30 effect sizes). The confidence intervals for both estimates are wide and crossing zero. For both, the comparison groups are primarily abstinence-based, with the exception of two studies where the comparison group condition was unclear. We found that both Assertative Community Treatment and Intensive Case Management were no better than treatment as usual, with average effect on substance use of 0.03 SD, 95% CI [-0.07, 0.13] and -0.47 SD, 95% CI [-0.72, -0.21] 0.05 SD, 95% CI [-0.28, 0.39] respectively. These findings are consistent with wider research, and it is important to note that we only examined the effect on substance use outcomes (these interventions can be effective in terms of other outcomes). We found that CM interventions can be effective in reducing substance use compared to treatment as usual, with an average effect of -0.47 SD, 95% CI (-0.72, -0.21). All of these results need to be considered in light of the quality of the underlying evidence. There were six further interventions where we undertook narrative synthesis. These syntheses suggest that Group Work, Harm Reduction Psychotherapy, and Therapeutic Communities are effective in reducing substance use, with mixed results found for Motivational Interviewing and Talking Therapies (including Cognitive Behavioural Therapy). The narrative synthesis suggested that Residential Rehabilitation was no better than treatment as usual in terms of reducing substance use for our population of interest.

Authors' Conclusions

Although our analysis of harm reduction versus treatment as usual, abstinence versus treatment as usual, and harm reduction versus abstinence suggests that these different approaches make little real difference to the outcomes achieved in comparison to treatment as usual. The findings suggest that some individual interventions are more effective than others. The overall low quality of the primary studies suggests that further primary impact research could be beneficial.

Disordered alcohol and substance use in Irish farmers: A cross-sectional survey

PURPOSE

Farming is a high-pressure occupation. Populations of farmers face significant health risks, including injury, mental illness, and in some cases, heavy alcohol use. However, there is little research on farmers' use of substances beyond alcohol. This study examines factors relating to Irish farmers' disordered alcohol and substance use.

METHODS

In accordance with STROBE guidelines for cross-sectional research and reporting, we examined disordered alcohol and substance use in 351 Irish farmers using the Alcohol Use Disorders Identification Tool (AUDIT) and Drug Use Disorders Identification Tool (DUDIT).

FINDINGS

While 28% of farmers did not drink, 40% of those who did drink exceeded the AUDIT threshold for disordered use. Similarly, while 95% of farmers did not use substances, 78% of farmers who did use substances exceeded the DUDIT threshold for disordered use. Age was the most important risk factor for disordered alcohol and substance use and correlated with other main risk factors: lower income, no children, part-time farmer, and full-time off-farm roles. Disordered drinking was highest in farmers engaged in full-time education.

CONCLUSIONS

This population of Irish farmers report broadly healthy alcohol and substance use behaviors. Irish farmers may serve as a model group whose strengths can be utilized in interventions within and beyond the Irish farming community. Our results confirm the importance of analyzing demographic factors in farmers' drinking and identify younger farmers as especially at-risk for harmful alcohol and substance use.

Heterogeneous trajectories of suicidal ideation among homeless youth: predictors and suicide-related outcomes

The current study examined heterogeneous trajectories of suicidal ideation among homeless youth experiencing suicidal ideation over 9 months in a randomized controlled intervention study. Suicidal homeless youth (N = 150) were randomly assigned to Cognitive Therapy for Suicide Prevention (CTSP) + Treatment as Usual (TAU) or TAU alone. Youth reported their suicidal ideation four times during a 9-month period. We also assessed pretreatment mental health, demographic information and session attendance as predictors of the subgroups, as well as suicide-related factors as outcomes at the 9-month follow-up. Growth mixture models suggested three distinct trajectory groups among youth: Fast Declining (74.7%), Chronic (19.3%), and Steadily Declining (6.0%). Youth in the Chronic group used more substances at baseline than the Steadily Declining group, were more likely to be White, non-Hispanic than the Fast Declining group, and attended more CTSP sessions than other groups. Contrastingly, youth in the Steadily Declining group all experienced childhood abuse. Finally, youth in the Chronic group showed significant higher risk for future suicide compared to those in the Fast Declining group at 9 months. Findings support the heterogeneity of treatment responses in suicide intervention among homeless youth, with implications to improve treatment efforts in this very high-risk population.

PROTOCOL: The effectiveness of abstinence-based and harm reduction-based interventions in reducing problematic substance use in adults who are experiencing severe and multiple disadvantage homelessness: A systematic review and meta-analysis

Background

Homelessness is a major social and public health concern. It is a traumatic experience, and can have a devastating effect on those experiencing it. People who are homeless often face significant barriers when accessing public services, and those experiencing more visible and extreme forms of homelessness have often faced adverse childhood events, extreme social disadvantage, physical, emotional and sexual abuse, neglect, low self-esteem, poor physical and mental health, and much lower life expectancy compared to the general population. Problematic substance use is disproportionately high amongst people experiencing homelessness, with many using drugs and alcohol to deal with the stress of living on the street, to keep warm, or to block out memories of previous abuse or trauma. Drug overdose is a major cause of death for people experiencing street homelessness. Substance dependency can also create barriers to successful transition to stable housing. There is ongoing policy interest in the effectiveness of different interventions that aim to stop, reduce or prevent problematic substance use, and there is specific interest in the relative effectiveness of interventions that adopt harm reduction or abstinence-based approaches.

Objectives

The objective of this review is to understand the effectiveness of different substance use interventions. The review will consider the effectiveness of harm reduction-based interventions, and abstinence-based interventions, for adults experiencing homelessness. The focus of the review is on high-income countries.

Search Methods

The primary source of studies for potential inclusion in this review is the Homelessness Effectiveness Studies Evidence and Gaps Maps (EGM). The first of these was published in 2018, with updates published in 2019 and 2020. A further update is due to be published in the summer of 2022. It is this update that provides the final list of studies from which this review will draw. The search for this update (EGM 4th edition) was completed in September 2021. Other potential studies will be identified through a call for grey evidence and hand-searching key journals.

Selection Criteria

Eligible studies will be impact evaluations with designs at levels, 3, 4 and 5 of the Maryland Scientific Methods scale. This therefore includes all studies categorised as either 'Randomised Controlled Trials' or 'nonexperimental designs with a comparison group' from the studies which form the basis of the Homelessness Effectiveness Studies Evidence and Gap Maps (EGM) created by CHI and the Campbell Collaboration. We are interested in studies that examine the effect of interventions on substance use outcomes. Studies to be excluded are those with designs at levels 1 and 2 of the Maryland Scientific Methods scale, for example, studies without a control or comparison group, 'before vs. after' designs (without an untreated comparison group), and cross-sectional regressions.

Data Collection and Analysis

Descriptive characteristics and statistical information in included studies will be coded and checked by at least two members of the review team. Studies selected for the review will be assessed for confidence in the findings using a critical appraisal tool for determining confidence in primary studies. Standardised effect sizes will be calculated and, if a study does not provide sufficient raw data for the calculation of an effect size, we will attempt to contact the author(s) to obtain this data. We will aim to use random-effects meta-analysis and robust-variance estimation procedures to synthesise effect sizes. If a study includes multiple effects, we will carry out a critical assessment to determine (even if only theoretically) whether the effects are likely to be dependent. Where we suspect dependent effects, we will determine whether we can account for these by robust variance estimation. We will explore the moderating influence of participant and study characteristics, such as gender, race, substances targeted and length of follow-up. Where effect sizes are converted from a binary to continuous measure (or vice versa), we will undertake a sensitivity analysis to investigate the effect of the inclusion of studies with a converted effect size in the meta-analysis by running an additional analysis with these studies omitted. We will also assess the sensitivity of results to inclusion of non-randomised studies and studies classified as low confidence in findings. All analyses will include an assessment of statistical heterogeneity. Finally, we will undertake analysis to assess whether publication bias is likely to be a factor in our findings.

Prevalence and Correlates of Illicit Substance Use Among Young Adults Experiencing Homelessness in Seven Cities Across the United States

Background

Young adults experiencing homelessness (YAEH) engage in substantially higher substance use rates than housed young adults. This current study builds on previous research by investigating the prevalence of and salient correlates of illicit substance use across a seven-city sample.

Methods

This study used the Homeless Youth Risk and Resiliency Survey (HYRRS) dataset, n=1426 Young adults experiencing homelessness to study patterns and correlates of illicit substance use.

Results

Multivariate logistic regression analyses were used to assess correlates of substance use. Study site, age, gender identity, sexual orientation, history of suicidal ideation, use of specific substances, and trading sex for drugs were associated with five types of illicit substance use (ecstasy, cocaine, crack, methamphetamine, and injection drug use).

Conclusion

Findings indicate that substance use interventions for YAEH must be multifaceted, addressing illicit and multiple substance use, along with the myriad factors associated with substance use among this at-risk group.

Understanding the Link between Victimization and Alcohol Use among Homeless Youth Using Ecological Momentary Assessment

Most prior research on victimization and alcohol use among homeless youth is retrospective and thus does not allow researchers to determine the sequencing of these events. We address this gap using ecological momentary assessment via short message service surveying with homeless youth during 30 days. Multilevel binary logistic regression results revealed that experiencing physical or sexual victimization on a specific day was positively associated with youth's drinking alcohol later that day. Because ecological momentary assessment via short message service allows for such specificity, we can link a specific victimization experience with a current drinking episode. Thus, the time ordering of daily events in the current study is a significant improvement over prior research. Understanding the timing between victimization and drinking alcohol is also important for intervention with this underserved population.

The Relative Influence of Injunctive and Descriptive Social Norms on Methamphetamine, Heroin, and Injection Drug Use Among Homeless Youths: The Impact of Different Referent Groups

The current study assessed the relative influence of both injunctive and descriptive norms in the context of different referent groups (i.e., family, street peers, home-based peers, and staff members) on past 30-day methamphetamine, heroin, and injection drug use behaviors of homeless youth. Cross-sectional data ( N = 911) were collected from three drop-in centers in Los Angeles, California. The study consisted of two parts: a social network interview and a computerized self-administered survey. Multivariate logistic regression models examined the association of objection to drug use from referent groups (injunctive norms; that is, street-based peers, home-based peers, relatives, staff members) and drug use of referent groups (descriptive norms) with youths’ substance use behaviors. Multivariate results indicated that the role of injunctive and descriptive norms varied across the three substance use behaviors and by referent group. Findings indicate the need to carefully consider the diversity of homeless youths’ networks in designing substance use interventions.

Network Approaches to Substance Use and HIV/Hepatitis C Risk among Homeless Youth and Adult Women in the United States: A Review

During the United States economic recession of 2008-2011, the number of homeless and unstably housed people in the United States increased considerably. Homeless adult women and unaccompanied homeless youth make up the most marginal segments of this population. Because homeless individuals are a hard to reach population, research into these marginal groups has traditionally been a challenge for researchers interested in substance abuse and mental health. Network analysis techniques and research strategies offer means for dealing with traditional challenges such as missing sampling frames, variation in definitions of homelessness and study inclusion criteria, and enumeration/population estimation procedures. This review focuses on the need for, and recent steps toward, solutions to these problems that involve network science strategies for data collection and analysis. Research from a range of fields is reviewed and organized according to a new stress process framework aimed at understanding how homeless status interacts with issues related to substance abuse and mental health. Three types of network innovation are discussed: network scale-up methods, a network ecology approach to social resources, and the integration of network variables into the proposed stress process model of homeless substance abuse and mental health. By employing network methods and integrating these methods into existing models, research on homeless and unstably housed women and unaccompanied young people can address existing research challenges and promote more effective intervention and care programs.

"I'm Not Waving, I'm Drowning": An Autoethnographical Exploration of Biographical Disruption and Reconstruction During Recovery From Prescribed Benzodiazepine Use

Benzodiazepines are group of drugs used mainly as sedatives, hypnotics, muscle relaxants, and anti-epileptics. Tapering off benzodiazepines is, for some users, a painful, traumatic, and protracted process. In this article, I use an autoethnographic approach, adopting the metaphor of water, to examine heuristically my experience of iatrogenic illness and recovery. I draw on personal journals and blog entries and former users' narratives to consider the particular form of biographical disruption associated with benzodiazepines and the processes involved in identity reconstruction. I emphasize the role of the online community in providing benzodiazepine users such as myself with a co-cultural community through which to share a voice and make sense of our experiences. I explain how the success stories of former users provided me with the hope that I, the "medical victim," could become the "victor" and in the process construct a new life and fresh identity.

An Inside Look at Homeless Youths' Social Networks: Perceptions of Substance Use Norms

Substance use among homeless young people is a pervasive problem, and there have been many efforts to understand more about the dynamics of this health compromising behavior. The current study examined perceived substance use norms within homeless youths' social networks utilizing in-depth interviews. The sample included 19 homeless individuals aged 16 to 21. Four elements of substance use within networks emerged: substance use choices, drug use safety issues, encouragement and/or discouragement, and appropriate situations in which substance use is condoned. These findings provide unique insight into the norms associated with drug and alcohol use within homeless youths' social networks.

Child Abuse, Street Victimization, and Substance Use Among Homeless Young Adults

Although previous research documents high rates of child abuse, street victimization, and substance use among homeless youth, few studies have investigated these three constructs simultaneously, and thus little is known about how various forms of victimization are uniquely associated with substance use among this population. The purpose of this article is to examine the relationship among child sexual and physical abuse, street victimization, and partner violence with substance use among 172 homeless young adults. Path analysis results revealed that males and those who reported parental drug problems were significantly more likely to have higher rates of substance use. Those who suffered more childhood physical and sexual abuse and those who experienced more types of relationship violence were more likely to report greater frequency of substance use. The intersection of various forms of victimization with substance use may have important implications for service providers working with this population.

The impact of psychosocial factors on subjective well-being among homeless young adults

Homeless young adults are one of this country's most vulnerable populations, and information surrounding issues of subjective well-being among this particularly diverse population is scarce. The purpose of this study was to examine the impact social support, future expectations, and homeless cultural factors have on subjective well-being among homeless young adults. A purposive sample of 185 homeless young people, ages 18 to 23, and known to use alcohol or drugs, participated in the study. Multiple regression analyses showed that participants who had a higher level of subjective well-being reported significantly higher levels of social support, more optimistic expectations of the future, and a better perception of the flow of time. More fatalistic views of the future significantly predicted lower levels of subjective well-being. Findings suggest that service providers should focus on understanding the strengths of individuals and, specifically, gain a deeper understanding of homeless young adults' support networks and views of the future.

The effect of victimization, mental health, and protective factors on crime and illicit drug use among homeless young adults

Although research has found high rates of child maltreatment, widespread victimization, and other negative outcomes among homeless youth and young adults, resiliency among this population has largely been understudied. Specifically, a gap remains in terms of how protective factors such as self-efficacy, low deviant beliefs, and religiosity operate among homeless youth and young adults. The purpose of this study is to examine the relationship between various forms of victimization, mental health, and protective factors with property and violent crime and illicit drug use among homeless young adults. Results from regression analyses indicate that running away from home more frequently, experiencing more physical victimization on the street, higher levels of self-efficacy, and more deviant beliefs were associated with greater property crime. Significant correlates of violent crime included being male, running away from home more frequently, greater sexual and physical victimization on the street, higher levels of self-efficacy, and more deviant beliefs. Finally, being male, running away more frequently from home, greater child physical abuse and partner victimization, and more deviant beliefs were all associated with greater illicit drug use. Self-efficacy was positively related to both property and violent crime, suggesting that it may not operate for homeless young adults in the same manner as it does for normative populations.