Development and validation of a Knowledge, Belief, and Behaviour Questionnaire on Sarcopenia for Older Adults (KBBQ-SOA): a study protocol based on the COSMIN guidelines

The lack of a standardized and theoretically grounded instrument to assess psychosocial determinants of sarcopenia prevention represents a critical gap in public health. This protocol describes the development and validation of the Knowledge, Belief, and Behaviour Questionnaire on Sarcopenia for Older Adults (KBBQ-SOA). Guided by the Consensus-based Standards for the selection of Health Measurement Instruments (COSMIN) and informed by the Knowledge-Belief-Behaviour framework, the study will be conducted in four sequential stages: (1) item generation and construct clarification through literature review, expert consultation, and semi-structured interviews; (2) content validation using a Delphi expert panel and cognitive interviews; (3) psychometric evaluation in a multi-site sample of 300–500 community-dwelling older adults across four diverse regions of China; and (4) assessment of interpretability and feasibility, including a preliminary evaluation of cross-cultural applicability. This paper presents the study design and methodology; no results are reported. The KBBQ-SOA is expected to be a rigorously validated, multi-dimensional instrument for assessing sarcopenia-related knowledge, beliefs, and behaviours. It may support the development and evaluation of targeted health education and behavioural interventions in older adult populations. https://doi.org/10.17605/OSF.IO/XMJY4 What is already known? ∙ Sarcopenia is a prevalent condition among older adults, yet there is no validated instrument specifically designed to assess their knowledge, beliefs, and behaviours related to it. ∙ Existing questionnaires often focus on single domains or lack a theoretical foundation linking knowledge, belief, and behaviour. ∙ The COSMIN guidelines provide a standardized framework for developing and validating health measurement instruments. What this paper adds? ∙ This study proposes a protocol for developing and validating the Knowledge, Belief, and Behaviour Questionnaire on Sarcopenia for Older Adults (KBBQ-SOA) based on the COSMIN framework. ∙ The protocol integrates mixed methods, including literature review, qualitative interviews, Delphi consultation, and psychometric testing, to ensure content and construct validity. ∙ The resulting instrument will provide a reliable and feasible tool to guide education, screening, and intervention strategies for sarcopenia among older adults.