Effectiveness of the Housing First model among substance users: a scoping review
Authors: Saldanha Susan , Tavitian Natalie , Lehman Elizabeth , Carey Lindsay , Higgs Peter 
Published: July 2024

Purpose
Housing First (HF) is an evidence-based practice effective in reducing homelessness among those who experience chronic homelessness. However, a strong synthesis evaluating the effectiveness of this intervention is lacking for people who use drugs. The purpose of this study is to explore international literature databases to identify the effectiveness of the HF programme among people who use drugs.

Design/methodology/approach
A modified framework from Arksey and O’Malley (2005) was used, namely: identifying the research question; developing inclusion and exclusion criteria; identifying relevant studies for study selection; charting the data; and collating, summarising and reporting the results.

Findings
Three main themes were identified: substance use related outcomes, housing-related outcomes and social outcomes. There is strong evidence that HF increases housing retention and reduces homelessness among chronically homeless people who use drugs. However, literature relating to substance use and social outcomes for this population report mixed and inconclusive findings.

Research limitations/implications
This scoping review concludes that additional research is required to conclusively determine whether HF is an effective intervention for homeless substance users. Future researchers must use formal assessments of substance use and ensure clear reporting of the HF intervention is accomplished. It is recommended for researchers and policymakers to consider the specific needs of the people who use drugs before implementation of HF for this population.

Practical implications
Differential effectiveness of HF through diagnostic subgroups such as alcohol use and drug use is varied with alcohol use being found to decrease due to the HF programme, but findings relating to other drug use outcomes are varied. As most previous studies used the Addiction Severity Index (ASI) to measure substance use among participants, however, the ASI, a self-reporting measure has unstable criterion validity and can cause under or over reporting of substance use. Structured toxicology or diagnostic assessments of substance use must be used for research instead to assist researchers in making firm conclusions about the reported rates.

Social implications
The slightly poorer housing outcomes among people who use substances indicate that this group may need more intensive approaches to finding and maintaining housing. Additional services for the group that address comorbid problems and consequences relating to substance use are required. It is suggested that housing should be provided within an integrated model that offers additional support services such as case management as when well matched to clients, case management appears to be an effective intervention among homeless sub-populations, as it reduces substance use, improves quality of life and health outcomes, improves social connectedness and increases housing tenure and satisfaction.

Originality/value
This scoping review concludes that additional research is required to conclusively determine whether HF is an effective intervention for homeless substance users. Future researchers must use formal assessments of substance use and ensure clear reporting of the HF intervention is accomplished. It is recommended for researchers and policymakers to consider the specific needs of the people who use drugs before HF implementation for this population.