Table 3 Study inclusion and exclusion criteria

Adults (aged 18+) who were homeless (or at risk of homelessness) and had accessed treatment for problematic drug and/or alcohol use (currently or in the 10 years prior to the study being conducted).

Participants other than adults (aged 18+) who were homeless (or at risk of homelessness) who had accessed treatment for problematic drug and/or alcohol use more than 10 years ago.

Published studies reporting primary qualitative research studies (any type) with sufficient rich data for synthesis.

Studies not reporting primary qualitative research studies (e.g. surveys, qualitative evidence syntheses). Studies using qualitative methods but which did not report sufficiently rich data for synthesis, e.g. mixed methods research where qualitative data were not presented separately.

Studies published from 2000 in English language.

Qualitative research reported out with these years and not in English language.

Studies that reported participants’ views/experiences of receiving treatment for problematic substance (drugs and alcohol of any type) use only.

Studies that did not report participants’ views/experiences of receiving treatment for problematic substance use. Studies that focused on substances other than drugs and alcohol (e.g. tobacco) or other types of addictions. Studies that included participants with dual diagnoses (e.g. problematic substance use and mental health problems). Studies that only reported the views of others (e.g. service providers).