Some services work to reduce problematic substance use by adults experiencing homelessness.
The review in brief
People experiencing homelessness sometimes have problems with substance use. This review looked at different services that try to help reduce substance use, to see if they worked. It found that giving people vouchers if they did not use substances worked better than conventional services (which might include no provision or alternative services), and that some evidence that other services might work. Assertative Community Treatment (ACT) and Intensive Case Management (ICM) did not make any difference.
What is this review about?
Substance use is higher among adults experiencing homelessness. Substance use can have terrible consequences, for example, drug overdose is a major cause of death for people experiencing homelessness. Many services try to reduce or stop substance, and it is important to know whether these do work. This review has looked at the available evidence to see whether a service is harm reduction based or abstinence based makes a difference to whether it works, whether these services work overall, and which individual services work.
What is the aim of this review?
This Campbell systematic review examines the effects of different interventions on substance use in adults experiencing homelessness. This review summarises 48 papers covering 9 different services.
What are the main findings of this review?
Most of the papers come from the United States and Canada, and there were no papers from the UK. Each paper compared a new substance use service (the intervention being evaluated) to conventional services, or doing nothing to help. Some of the studies used high quality methods, but most did not.
Overall, we found that the new substance use services that were tested in the 48 papers covered by our review worked better than conventional services.
We looked at whether harm reduction-based services work better than conventional services, whether abstinence-based services work better than conventional services, and whether harm reduction-based services work better than abstinence-based. This analysis suggests that these different approaches make little real difference to the outcomes achieved. Contingency Management (CM), where vouchers are given to someone to stop using substances, works much better than conventional services. Group Work, Harm Reduction Psychotherapy, and Therapeutic Communities might work reducing substance use, with mixed results found for Motivational Interviewing and Talking Therapies (including Cognitive Behavioural Therapy). The evidence suggested that Residential Rehabilitation, ACT, and ICM did not make a difference compared to conventional services.
Only three papers looked at women experiencing homelessness, and overall three quarters of those involved in the studies were men. This is partly because men are more likely to use substances, and are more likely to experience street homelessness. But the lack of women in these studies is a significant gap.
What do the findings of this review mean?
Most of the papers included are from the US and Canada, and there are big differences between homelessness there and in the UK or Europe. We need more evidence from the UK about what types of substance use services work for people experiencing homelessness. We also need more evidence about women’s homelessness, and which services work best for women experiencing homelessness to reduce their substance use.
How up-to-date is this review?
Papers published before September 2021 are included in this review.