Measurement properties of self-reported measures assessing social inclusion in adults diagnosed with mental illness: a systematic review protocol

Background : Social inclusion is widely recognized as a key factor in mental health recovery and overall well-being. However, its conceptualization and measurement remain inconsistent across research and practice. Few self-reported measures have been developed to specifically assess social inclusion among persons diagnosed with mental illness, but many have been developed to measure similar constructs, such as community integration, social/ community participation, social/ community engagement, social/ community involvement, (psycho)social functioning, social well-being or recovery. The aim of this study is to identify, compare and synthesize all available self-reported measures assessing social inclusion and similar constructs in adults diagnosed with mental illness, evaluate their measurement properties, identify potential gaps and provide recommendations for future research. Methods : This systematic review protocol follows the COnsensus-based Standards for the Selection of health Measurement INstruments (COSMIN) guidelines. A comprehensive literature search was conducted in four electronic databases: PubMed, PsycInfo, Scopus and Web of Science. Other studies will be identified by reference list checking or contacting the authors. A detailed protocol for a systematic literature review of social inclusion measures (and similar concepts) developed, validated and/or adapted for adults diagnosed with mental illness is presented, including research question, eligibility criteria, search strategy, data selection and collection process, assessment of the methodological quality of individual studies and patient-reported outcome measures (PROMs), assessment of the quality of evidence, and strategy for data syntheses. Discussion : Given the complexity and lack of consensus around the concept of social inclusion of people with mental illness, along with the growing number of measures, a systematic review is both timely and necessary. A multidimensional approach, which existing tools are compared, can highlight shared features, gaps, and future research needs, supporting a more unified understanding of social inclusion in mental health. Systematic review registration: PROSPERO 2025 CRD420251009903.