The impact of a Housing First randomized controlled trial on substance use problems among homeless individuals with mental illness

Abstract Background There is strong evidence that Housing First interventions are effective in improving housing stability and quality of life among homeless people with mental illness and addictions. However, there is very little evidence on the effectiveness of Housing First in improving substance use-related outcomes in this population. This study uses a randomized control design to examine the effects of scatter-site Housing First on substance use outcomes in a large urban centre. Methods Substance use outcomes were compared between a Housing First intervention and treatment as usual group in a sample of 575 individuals experiencing homelessness and mental illness, with or without a co-occurring substance use problem, in the At Home/Chez Soi trial in Toronto, Canada. Generalized linear models were used to compare study arms with respect to change in substance use outcomes over time (baseline, 6, 12, 18 and 24 month). Results At 24 months, participants in the Housing First intervention had significantly greater reductions in number of days experiencing alcohol problems and amount of money spent on alcohol than participants in the Treatment as Usual group. No differences between the study arms in illicit drug outcomes were found at 24 months. Conclusions These findings show that a Housing First intervention can contribute to reductions in alcohol problems over time. However, the lack of effect of the intervention on illicit drug problems suggests that individuals experiencing homelessness, mental illness and drug problems may need additional supports to reduce use. Trial Registration: Current controlled trials ISRCTN42520374.