Abstinent-contingent housing and treatment retention among crack-cocaine-dependent homeless persons

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.

Effectiveness of secondary prevention and treatment interventions for crack-cocaine abuse: a comprehensive narrative overview of English-language studies

There are an estimated several million crack-cocaine users globally; use is highest in the Americas. Most crack users are socio-economically marginalized (e.g., homeless), and feature elevated risks for morbidity (e.g., blood-borne viruses), mortality and crime/violence involvement, resulting in extensive burdens. No comprehensive reviews of evidence-based prevention and/or treatment interventions specifically for crack use exist. We conducted a comprehensive narrative overview of English-language studies on the efficacy of secondary prevention and treatment interventions for crack (cocaine) abuse/dependence. Literature searches (1990-2014) using pertinent keywords were conducted in main scientific databases. Titles/abstracts were reviewed for relevance, and full studies were included in the review if involving a primary prevention/treatment intervention study comprising a substantive crack user sample. Intervention outcomes considered included drug use, health risks/status (e.g., HIV or sexual risks) and select social outcome indicators. Targeted (e.g., behavioral/community-based) prevention measures show mixed and short-term effects on crack use/HIV risk outcomes. Material (e.g., safer crack use kit distribution) interventions also document modest efficacy in risk reduction; empirical assessments of environmental (e.g., drug consumption facilities) for crack smokers are not available. Diverse psycho-social treatment (including contingency management) interventions for crack abuse/dependence show some positive but also limited/short-term efficacy, yet likely constitute best currently available treatment options. Ancillary treatments show little effects but are understudied. Despite ample studies, pharmaco-therapeutic/immunotherapy treatment agents have not produced convincing evidence; select agents may hold potential combined with personalized approaches and/or psycho-social strategies. No comprehensively effective 'gold-standard' prevention/treatment interventions for crack abuse exist; concerted research towards improved interventions is urgently needed.

Lost in translation? Moving contingency management and cognitive behavioral therapy into clinical practice

In the treatment of addictions, the gap between the availability of evidence-based therapies and their limited implementation in practice has not yet been bridged. Two empirically validated behavioral therapies, contingency management (CM) and cognitive behavioral therapy (CBT), exemplify this challenge. Both have a relatively strong level of empirical support but each has weak and uneven adoption in clinical practice. This review highlights examples of how barriers to their implementation in practice have been addressed systematically, using the Stage Model of Behavioral Therapies Development as an organizing framework. For CM, barriers such as cost and ideology have been addressed through the development of lower-cost and other adaptations to make it more community friendly. For CBT, barriers such as relative complexity, lack of trained providers, and need for supervision have been addressed via conversion to standardized computer-assisted versions that can serve as clinician extenders. Although these and other modifications have rendered both interventions more disseminable, diffusion of innovation remains a complex, often unpredictable process. The existing specialty addiction-treatment system may require significant reforms to fully implement CBT and CM, particularly greater focus on definable treatment goals and performance-based outcomes.

Contingency management for cocaine treatment: cash vs. vouchers

The efficacy of contingency management (CM) for treating drug abuse is well supported. The most widely used form of CM is voucher-based reinforcement therapy (VBRT), where clients receive an escalating schedule of vouchers that can be redeemed for goods and services for meeting treatment goals. Though generally rejected due to concerns about potential harms to drug using participants, research suggests that cash may be a more effective reinforcer. This three-group randomized trial compared the efficacy of cash-based reinforcement therapy (CBRT) to VBRT and a non-CM condition on cocaine abstinence and treatment attendance; and examined whether CBRT resulted in greater levels of harm than VBRT. Findings indicated that the CBRT was as effective as VBRT when compared to the non-CM condition and that it did not increase rates of drug use, cravings, or high-risk behaviors. Future research should examine potential cost savings associated with a cash-based CM approach as this could have important implications for the wider adoption of the CM model.

Cocaine behavioral economics: from the naturalistic environment to the controlled laboratory setting

BACKGROUND

We previously observed that behavioral economic factors predict naturalistic heroin seeking behavior that correlates with opioid seeking in the experimental laboratory. The present study sought to replicate and extend these prior findings with regular cocaine users.

METHODS

Participants (N=83) completed a semi-structured interview to establish income-generating and cocaine-purchasing/use repertoire during the past month. Questions addressed sources/amounts of income and expenditures; price (money and time) per purchase; and frequency/amounts of cocaine purchased and consumed. Naturalistic cocaine purchasing and use patterns were: (1) analyzed as a function of income quartile, (2) perturbed by hypothetical changes in cost factors to assess changes in purchasing/use habits, and (3) correlated with experimental cocaine seeking.

RESULTS

Income was positively related to naturalistic cocaine seeking/use pattern (i.e., income elastic), and behaviors were cost-efficient and sensitive to supply chain. Income was unrelated to proportional expenditure on cocaine (≈55%) but inversely related to food expenditure. In all hypothetical scenarios (changes in income or dealer, loss of income assistance from government or family/friends, and increasing arrest risk when purchasing), the high-income group reported they would continue to use more cocaine daily than other groups. Number of laboratory cocaine choices significantly correlated with cocaine purchase time (positively) and purity of cocaine (negatively) in the naturalistic setting.

CONCLUSIONS

These results replicate and extend findings with regular heroin users, demonstrate the importance of income, cost-efficiency and supply-mindedness in cocaine seeking/use, and suggest that this interview-based approach has good external validity.

Outreach with street-involved youth: a quantitative and qualitative review of the literature

Outreach workers meet with street-involved youth in their environment, and attempt to engage them in services vital to their well-being. The goal of this study is to conduct a systematic review of both the quantitative and qualitative research that explores outreach with street-involved youth. Using 16 outreach programs with quantitative information, our meta-analysis found that 63% of youth who are contacted through outreach later participate in the offered service. Our meta-synthesis of 31 qualitative articles on outreach uncovered 13 themes across 4 conceptual domains of interest. Themes pertaining to the therapeutic relationship, flexibility, and youth-centric programming had a large presence among the majority of the articles. Outreach with street-involved youth, when characterized through a strong bond between worker and youth, is an effective strategy for involving youth in agency services.

Effectiveness of interventions to improve the health and housing status of homeless people: a rapid systematic review

BACKGROUND

Research on interventions to positively impact health and housing status of people who are homeless has received substantially increased attention over the past 5 years. This rapid review examines recent evidence regarding interventions that have been shown to improve the health of homeless people, with particular focus on the effect of these interventions on housing status.

METHODS

A total of 1,546 articles were identified by a structured search of five electronic databases, a hand search of grey literature and relevant journals, and contact with experts. Two reviewers independently screened the first 10% of titles and abstracts for relevance. Inter-rater reliability was high and as a result only one reviewer screened the remaining titles and abstracts. Articles were included if they were published between January 2004 and December 2009 and examined the effectiveness of an intervention to improve the health or healthcare utilization of people who were homeless, marginally housed, or at risk of homelessness. Two reviewers independently scored all relevant articles for quality.

RESULTS

Eighty-four relevant studies were identified; none were of strong quality while ten were rated of moderate quality. For homeless people with mental illness, provision of housing upon hospital discharge was effective in improving sustained housing. For homeless people with substance abuse issues or concurrent disorders, provision of housing was associated with decreased substance use, relapses from periods of substance abstinence, and health services utilization, and increased housing tenure. Abstinent dependent housing was more effective in supporting housing status, substance abstinence, and improved psychiatric outcomes than non-abstinence dependent housing or no housing. Provision of housing also improved health outcomes among homeless populations with HIV. Health promotion programs can decrease risk behaviours among homeless populations.

CONCLUSIONS

These studies provide important new evidence regarding interventions to improve health, housing status, and access to healthcare for homeless populations. The additional studies included in this current review provide further support for earlier evidence which found that coordinated treatment programs for homeless persons with concurrent mental illness and substance misuse issues usually result in better health and access to healthcare than usual care. This review also provides a synthesis of existing evidence regarding interventions that specifically support homeless populations with HIV.

Sober housing and motivational interviewing: the Treatment Access Project

This paper describes an innovative program that provides rental subsidies for sober housing and supportive services to persons in early recovery who are homeless and have substance use disorders. Preliminary data point to the success of this program in enhancing recovery and exiting from homelessness. In supporting sober house placements, the Treatment Access Project creates a bridge that supports these individuals in their transition from clinical treatment services to the community. Integration with natural community supports can help to build self-efficacy, which can enhance the likelihood that this population will obtain and maintain abstinence, gainful employment, and permanent housing.

Substance abuse and personality disorders in homeless drop-in center clients: symptom severity and psychotherapy retention in a randomized clinical trial

This study evaluated the psychiatric symptoms, psychosocial problems, and treatment response of personality-disordered substance abusers receiving services within a homeless drop-in center. Fifty-two homeless clients were assessed after program admission and randomly assigned to receive either individual psychotherapy focused on personality disorder and substance abuse relapse prevention (dual-focus schema therapy [DFST]) or standard group substance abuse counseling (SAC). Client functioning was assessed using measures of personality disorder, psychiatric symptoms, early maladaptive schemas, interpersonal problems, and addiction-related psychosocial impairment. Therapy retention (total weeks in treatment) and utilization (number of weeks in which sessions were attended) were the primary outcomes. Although rates of cluster B personality disorders were comparable to other substance dependent samples, clusters A and C disorders were disproportionately more common. Clients reported significant psychiatric symptoms, criminality, and psychosocial impairment, yet made limited lifetime use of mental health services. Overall, there was greater utilization of individual DFST than group SAC. However, clients with more severe personality disorder symptoms demonstrated better utilization of SAC than DFST.

To house or not to house: the effects of providing housing to homeless substance abusers in treatment

OBJECTIVES

Housing typically is not provided to homeless persons during drug abuse treatment. We examined how treatment outcomes were affected under 3 different housing provision conditions.

METHODS

We studied 196 cocaine-dependent participants who received day treatment and no housing (NH), housing contingent on drug abstinence (ACH), or housing not contingent on abstinence (NACH). Drug use was monitored with urine testing.

RESULTS

The ACH group had a higher prevalence of drug abstinence than the NACH group (after control for treatment attendance), which in turn had a higher prevalence than the NH group. All 3 groups showed significant improvement in maintaining employment and housing.

CONCLUSIONS

The results of this and previous trials indicate that providing abstinence-contingent housing to homeless substance abusers in treatment is an efficacious, effective, and practical intervention. Programs to provide such housing should be considered in policy initiatives.

Transitions during effective treatment for cocaine-abusing homeless persons: establishing abstinence, lapse, and relapse, and reestablishing abstinence

Data are reported on drug use among cocaine-dependent homeless persons who participated in a clinical trial that compared day treatment only (DT, n = 69) with day treatment plus abstinent-contingent housing and work (DT+, n = 72). Drug use was measured with multiple weekly urine toxicologies. Compared with DT participants, more DT+ participants established abstinence, maintained abstinence for longer durations, were marginally significantly more likely to lapse, and significantly less likely to relapse. Of all participants who established abstinence and then relapsed, DT+ participants relapsed later and were more likely to reestablish abstinence. These analyses yield information on the processes involved in the manner in which drug use changes as a result of abstinent-contingent housing and work.

A snapshot of substance abuse among homeless and runaway youth in Denver, Colorado

We report on results of a one-day survey measuring rates of substance use and HIV risk behaviors among the homeless youth population of Denver, Colorado. On March 15, 2001, staff of Urban Peak, conducted a single-day survey of homeless and runaway youth in the Denver metropolitan region, going to locations known to be frequented by this population. All youth encountered were asked to fill out a brief survey asking about past nine month use of the following substances: alcohol, marijuana, cocaine, methamphetamine, heroin, hallucinogens, ecstasy and ketamine, and HIV risk behaviors. Chi-square analyses of the association of substance used and gender, age, living situation, and ethnicity were conducted. In addition, the use of any club drug was examined. One-hundred-eighty-six homeless or runaway youth were surveyed; 74 percent were between 16 and 25. Rates of use over the last nine months were as follows: alcohol, 69 percent; marijuana, 75 percent; methamphetamine, 18 percent; cocaine, 19 percent; heroin, 12 percent; hallucinogens, 30 percent; ecstasy, 25 percent; and ketamine, 13 percent. Eleven percent reported trading sex for drugs, money, food, or shelter; and 13 percent reported sharing needles. There were significant associations between living situation and use of marijuana, cocaine and hallucinogens. Prevalence rates of club drugs show 75 percent, 77 percent and 77 percent of homeless or runaway youth ihaving used ecstasy, ketamine and hallucinogens one to three times per month over the last nine months, respectively. Prevalence rates of substance use among homeless youth in the Denver metropolitan are similar to rates reported in other larger metropolitan areas. Routine screening for every substance needs to be part of the assessment for all homeless youth. Initial data points to a need for more research exploring protective factors among this population and to better understand the prevalence of club drug use.

Diagnostic compared with abstinence outcomes of day treatment and contingency management among cocaine-dependent homeless persons

Substance use disorder diagnoses were used as a treatment outcome measure in a randomized comparison of day treatment (DT) and day treatment plus contingency management (DT+) among homeless persons with primarily crack/cocaine disorders. Participants (N = 127, DT+ = 69, DT = 58, 73.2% male, 82.7% African American) were assessed at baseline and 6-month treatment completion. Binary positive and negative diagnostic outcomes for cocaine, marijuana, and alcohol were compared by treatment group. DT+ was 2.1 times more likely to have a positive treatment outcome than DT. Concordance between diagnostic change and point and continuous abstinence outcomes were found. The use of diagnostic change can be a practical addition to drug toxicology and self-report treatment outcome measures for research and practice.