摘要：Objectives. We examined the relationship between substance dependence and residential stability in homeless adults with current mental disorders 12 months after randomization to Housing First programs or treatment as usual (no housing or support through the study). Methods. The Vancouver At Home study in Canada included 2 randomized controlled trials of Housing First interventions. Eligible participants met the criteria for homelessness or precarious housing, as well as a current mental disorder. Residential stability was defined as the number of days in stable residences 12 months after randomization. We used negative binomial regression modeling to examine the independent association between residential stability and substance dependence. Results. We recruited 497 participants, and 58% (n = 288) met the criteria for substance dependence. We found no significant association between substance dependence and residential stability (adjusted incidence rate ratio = 0.97; 95% confidence interval = 0.69, 1.35) after adjusting for housing intervention, employment, sociodemographics, chronic health conditions, mental disorder severity, psychiatric symptoms, and lifetime duration of homelessness. Conclusions. People with mental disorders might achieve similar levels of housing stability from Housing First regardless of whether they experience concurrent substance dependence. The combination of homelessness, substance use, and mental illness is challenging for affected individuals and society to address. Estimates of the prevalence of substance use disorders among homeless populations vary between 29% and 75%. 1–4 Substance use among persons who are homeless has been associated with lower treatment retention, 5 higher rates of posttreatment relapse, 6 premature mortality, 7 and longer periods of homelessness. 8 Therefore, problematic substance use is a substantial barrier to existing homelessness 9 and contributes to social marginalization. 10–12 In recent years, Housing First programs have demonstrated increased residential stability among those who are homeless and have a mental illness. 13,14 More recently, Housing First has been shown to be effective among homeless individuals with active substance use disorders. 4,15 However, it is unclear whether Housing First interventions are effective in the context of active and severe polysubstance use. 16 In one of the original Housing First studies, 14 heavy use of drugs was defined as using for 4 days in the previous 6 months and heavy alcohol use as drinking for 28 days in the past 6 months. This level of use does not represent the experience of homeless individuals with substance use and mental disorders in Vancouver, British Columbia, many of whom engage in frequent and severe polysubstance use. 17–19 Kertesz et al. 16 cautioned that the currently favored policy approach of Housing First might be overreaching the evidence when applied to active substance users and those with severe addictions. Housing First has been successful in improving residential stability among refractory alcoholics, 20,21 but no data have yet been reported among homeless persons with active illicit drug use. A number of studies have found that ongoing substance use was associated with lower residential stability among previously homeless persons who received housing. 22–26 For example, a multisite observational study compared Housing First versus residential treatment or transitional housing before being placed in supported community housing among chronically homeless adults. The authors reported no advantages for participants who received treatment before being assigned supported community housing compared with the Housing First group in terms of days housed and self-reported health status. However, the group that received residential treatment before community housing incurred higher total health service costs. 27 Furthermore, requiring abstinence as a criterion for admission to transitional housing has not been found to be predictive of better housing outcomes postdischarge. 28,29 Interestingly, abstinence-oriented contingency management has been shown in a series of studies to improve housing stability among individuals who are homeless and dependent on crack cocaine. 30 These studies, however, did not include individuals with psychosis or other forms of substance dependence, and their housing time was limited, making comparisons between their research and Housing First studies difficult. 31 To date, there have been no randomized controlled trials of Housing First among persons who are homeless with concurrent disorders (co-occurring substance dependence and mental disorders). We hypothesized that these individuals would have lower levels of residential stability than those without substance dependence. We therefore examined the relationship between substance dependence and residential stability in homeless adults with current mental disorders who participated in The Vancouver At Home study.
