Associations between medical cannabis and other drug use among unstably housed women

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.

Housing Instability Associated with Return to Stimulant Use among Previously Abstaining Women

Stimulant use among unstably housed individuals is associated with increased risks of psychiatric co-morbidity, violence, HIV transmission, and overdose. Due to a lack of highly effective treatments, evidence-based policies targeting the prevention of stimulant use disorder are of critical importance. However, little empirical evidence exists on risks associated with initiating or returning to stimulant use among at-risk populations. In a longitudinal cohort of unstably housed women in San Francisco (2016-2019), self-reported data on stimulant use, housing status, and mental health were collected monthly for up to 6 months, and factors associated with initiating stimulants after a period of non-use were identified through logistic regression. Among 245 participants, 42 (17.1%) started using cocaine and 46 (18.8%) started using methamphetamine. In analyses adjusting for demographics and socio-structural exposures over the preceding month, experiencing street homelessness was associated with initiating cocaine use (AOR: 2.10; 95% CI: 1.04, 4.25) and sheltered homelessness with initiating methamphetamine use (AOR: 2.57; 95% CI: 1.37, 4.79). Other factors-including race, income, unmet subsistence needs, mental health, and treatment adherence-did not reach levels of significance, suggesting the paramount importance of policies directed toward improving access to permanent supportive housing to prevent stimulant use among unstably housed women.

Connectedness Based on Shared Engagement Predicts Remote Biochemically Verified Quit Status Within Smoking Cessation Treatment Groups on Facebook

INTRODUCTION

Engagement with online content and online social network integration are associated with smoking behavior change, but less is known about social dynamics of shared engagement between participants in group-based social media interventions.

METHODS

Participants were 251 young adult smokers aged 18 to 25 assigned to one of 29 secret Facebook groups tailored to their readiness to quit smoking ("pre-contemplation," "contemplation," and "preparation"). Groups varied in size and were randomly assigned to receive monetary incentives for engagement. All groups received daily posts for 90 days and were assessed for remote biochemically verified smoking abstinence at the end of the intervention. Across 29 groups, we examined associations between group features (group size, incentive condition, readiness to quit) with how connected members were within the group based on shared engagement with the same content (measured by density). At the individual level, we examined associations between 7-day biochemically verified smoking abstinence and how connected an individual was within the group (measured by degree centrality).

RESULTS

After adjusting for comment volume, being in a contemplation group (vs. pre-contemplation group) was associated with a decrease in comment-based density. Individual degree centrality was significantly associated with biochemically verified smoking abstinence for both comments and likes.

CONCLUSIONS

Future group-based social media interventions for smoking cessation may want to focus on promoting connected engagement between participants, rather than simply quantity of engagement.

IMPLICATIONS

Participants in a smoking cessation intervention delivered through Facebook groups were more likely to have biochemically verified smoking abstinence if they were more connected to the rest of the group via shared engagement. Promoting shared engagement between participants may be more likely to promote behavior change than volume of engagement alone.

The emergence of innovative cannabis distribution projects in the downtown eastside of Vancouver, Canada

The ongoing overdose crisis in the United States and Canada has highlighted the urgent need for innovative interventions to reduce drug-related harms. This, in turn, has led to increased interest in the potential of cannabis as a harm reduction strategy. While Canada has recently legalized cannabis, meaningful barriers to accessing legal cannabis remain for people who use drugs (PWUD) from marginalized communities. In the Downtown Eastside of Vancouver, Canada, innovative, grassroots cannabis distribution programs that dispense cannabis and cannabis products from unregulated sources to PWUD for free have recently emerged. In this study, we draw upon 23 in-depth qualitative interviews and ethnographic fieldwork with PWUD who access these programs. We found that these distribution programs play an important function in bridging access to cannabis for PWUD in a structurally disadvantaged neighborhood and do so by implementing few restrictions on who can access, providing a variety of cannabis products that would otherwise be inaccessible, and distributing cannabis at no cost. In addition, many people reported the program spaces provided an avenue to socialize and connect. Most of our participants reported that legal cannabis was inaccessible both through the legal medical and non-medical systems. Considering Canadian governments have made important regulatory changes in regards to cannabis, understanding emerging patterns and the structural barriers to accessing legal cannabis will be critical to maximizing the potential uses of cannabis as a harm reduction tool and ensuring equitable access to structurally disadvantaged populations. Examining the impact of cannabis use on PWUD and ensuring these groups have access to cannabis is an important component in determining whether cannabis deregulation reduces drug-related harms.