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This Campbell systematic review examines the effectiveness of interventions to reduce homelessness and increase residential stability for individuals who are homeless, or at risk of becoming homeless. Forty-three studies were included in the review, 37 of which are from the USA. Included interventions perform better than the usual services at reducing homelessness or improving housing stability in all comparisons. These interventions are: High intensity case managementHousing FirstCritical time interventionAbstinence-contingent housingNon-abstinence-contingent housing with high intensity case managementHousing vouchersResidential treatment These interventions seem to have similar beneficial effects, so it is unclear which of these is best with respect to reducing homelessness and increasing housing stability.

PLAIN LANGUAGE SUMMARY

There are large numbers of homeless people around the world. Interventions to address homelessness seem to be effective, though better quality evidence is required. There are large numbers of homeless people around the world. Recent estimates are over 500,000 people in the USA, 100,000 in Australia and 30,000 in Sweden. Efforts to combat homelessness have been made on national levels as well as at local government levels.This review assesses the effectiveness of interventions combining housing and case management as a means to reduce homelessness and increase residential stability for individuals who are homeless, or at risk of becoming homeless. Included studies were randomized controlled trials of interventions for individuals who were already, or at-risk of becoming, homeless, and which measured impact on homelessness or housing stability with follow-up of at least one year.A total of 43 studies were included. The majority of the studies (37) were conducted in the United States, with three from the United Kingdom and one each from Australia, Canada, and Denmark. Included interventions perform better than the usual services at reducing homelessness or improving housing stability in all comparisons. These interventions are: High intensity case managementHousing FirstCritical time interventionAbstinence-contingent housingNon-abstinence-contingent housing with high intensity case managementHousing vouchersResidential treatment These interventions seem to have similar beneficial effects, so it is unclear which of these is best with respect to reducing homelessness and increasing housing stability. A range of housing programs and case management interventions appear to reduce homelessness and improve housing stability, compared to usual services.However, there is uncertainty in this finding as most the studies have risk of bias due to poor reporting, lack of blinding, or poor randomization or allocation concealment of participants. In addition to the general need for better conducted and reported studies, there are specific gaps in the research with respect to: 1) disadvantaged youth; 2) abstinence-contingent housing with case management or day treatment; 3) non-abstinence contingent housing comparing group vs independent living; 4) Housing First compared to interventions other than usual services, and; 5) studies outside of the USA. The review authors searched for studies published up to January 2016. This Campbell systematic review was published in February 2018.

EXECUTIVE SUMMARY

The United Nations Universal Declaration of Human Rights (Article 25) states that everyone has a right to housing. However, this right is far from being realized for many people worldwide. According to the United Nations High Commissioner for Refugees (UNHCR), there are approximately 100 million homeless people worldwide. The aim of this report is to contribute evidence to inform future decision making and practice for preventing and reducing homelessness. To identify, appraise and summarize the evidence on the effectiveness of housing programs and case management to improve housing stability and reduce homelessness among people who are homeless or at-risk of becoming homeless. We conducted a systematic review in accordance with the Norwegian Knowledge Centre's handbook. We systematically searched for literature in relevant databases and conducted a grey literature search which was last updated in January 2016. Randomized controlled trials that included individuals who were already, or at-risk of becoming, homeless were included if they examined the effectiveness of relevant interventions on homelessness or housing stability. There were no limitations regarding language, country or length of homelessness. Two reviewers screened 2,918 abstracts and titles for inclusion. They read potentially relevant references in full, and included relevant studies in the review. We pooled the results and conducted meta-analyses when possible. Our certainty in the primary outcomes was assessed using the Grading of Recommendations Assessment, Development, and Evaluation for effectiveness approach (GRADE). We included 43 relevant studies (described in 78 publications) that examined the effectiveness of housing programs and/or case management services on homelessness and/or housing stability. The results are summarized below. Briefly, we found that the included interventions performed better than the usual services in all comparisons. However, certainty in the findings varied from very low to moderate. Most of the studies were assessed as having high risk of bias due to poor reporting, lack of blinding, or poor randomization and/or allocation concealment of participants. Case management is a process where clients are assigned case managers who assess, plan and facilitate access to health and social services necessary for the client's recovery. The intensity of these services can vary. One specific model is Critical time intervention, which is based on the same principles, but offered in three three-month periods that decrease in intensity.High intensity case management compared to usual services has generally more positive effects: It probably reduces the number of individuals who are homeless after 12-18 months by almost half (RR=0.59, 95%CI=0.41 to 0.87)(moderate certainty evidence); It may increase the number of people living in stable housing after 12-18 months and reduce the number of days an individual spends homeless (low certainty evidence), however; it may have no effect on the number of individuals who experience some homelessness during a two year period (low certainty evidence). When compared to low intensity case management, it may have little or no effect on time spent in stable housing (low certainty evidence).Critical time intervention compared to usual services may 1) have no effect on the number of people who experience homelessness, 2) lead to fewer days spent homeless, 3) lead to more days spent not homeless and, 4) reduce the amount of time it takes to move from shelter to independent housing (low certainty evidence). Abstinence-contingent housing is housing provided with the expectation that residents will remain sober. The results showed that abstinence-contingent housing may lead to fewer days spent homeless, compared with usual services (low certainty evidence). Non-abstinence-contingent housing is housing provided with no expectations regarding sobriety of residents. Housing First is the name of one specific non-abstinence-contingent housing program. When compared to usual services Housing First probably reduces the number of days spent homeless (MD=-62.5, 95%CI=-86.86 to -38.14) and increases the number of days in stable housing (MD=110.1, 95%CI=93.05 to 127.15) (moderate certainty evidence). In addition, it may increase the number of people placed in permanent housing after 20 months (low certainty evidence).Non-abstinence-contingent housing programs (not specified as Housing First) in combination with high intensity case management may reduce homelessness, compared to usual services (low certainty evidence). Group living arrangements may be better than individual apartments at reducing homelessness (low certainty evidence). Housing vouchers is a housing allowance given to certain groups of people who qualify. The results showed that it mayreduce homelessness and improve housing stability, compared with usual services or case management (low certainty evidence). Residential treatment is a type of housing offered to clients who also need treatment for mental illness or substance abuse. We found that it mayreduce homelessness and improve housing stability, compared with usual services (low certainty evidence). We found that a range of housing programs and case management interventions appear to reduce homelessness and improve housing stability, compared to usual services. The findings showed no indication of housing programs or case management resulting in poorer outcomes for homeless or at-risk individuals than usual services.Aside from a general need for better conducted and reported studies, there are specific gaps in the research. We identified research gaps concerning: 1)Disadvantaged youth; 2) Abstinence-contingent housing with case management or day treatment; 3) Non-abstinence contingent housing, specifically different living arrangements (group vs independent living); 4) Housing First compared to interventions other than usual services, and; 5) All interventions from contexts other than the USA.