The Centre for Homelessness Impact has appointed the Policy Evaluation and Research Unit at Manchester to undertake a systematic review of the effectiveness of harm reduction versus abstinence-based substance use interventions for people experiencing homelessness.

Systematic reviews are transparent, comprehensive, and structured reviews of existing evidence around the effectiveness of interventions. As part of the search strategy for systematic review, we are undertaking a Call for Evidence, inviting people with lived experience, researchers, commissioners, service providers and wider stakeholders to submit relevant grey evidence for consideration in the review. We are looking for evidence that is:

  • empirical, based on research that:
  •      i) gives voice to people with experience of homelessness;
  •      ii) measures the impact of interventions (before and after, quasi-experimental, randomised controlled trial);
  •      iii)identifies the barriers to, and facilitators of, successful implementation of interventions
  • is about interventions aimed at reducing or stopping problematic substance misuse, using harm reduction or abstinence-based approaches
  • is not published in a book or academic journal
  • is specific to the UK, or England, Northern Ireland, Scotland or Wales.

Please submit your evidence by emailing Jordan Harrison at Please use the subject header ‘Call for evidence’ and attach a copy of the relevant publication, or link to where it is published. Any evidence must be submitted by Friday 8th January 2021 to be considered.