Abstract
INTRODUCTION: The healthcare system is complex, involving multiple interactions among individuals, organisations and systems. Many patients, particularly those with limited health system literacy, struggle to navigate it. A reliable instrument is crucial for accurately measuring individuals' navigational abilities. However, a systematic review of psychometric properties of existing instruments for measuring health system literacy has not been conducted. This review aims to provide a comprehensive assessment of methodological quality and measurement properties of these instruments. METHODS AND ANALYSIS: A search was conducted in MEDLINE, EMBASE, CINAHL, APA Psyfor, SCOPUS, Web of Science and Google Scholar from the date the database was created to 14 December 2024. Eligible studies include those published in English and focusing on developing and validating an instrument for measuring the construct of health system literacy in adults aged 18 or older. Two researchers will independently review, select and extract eligible studies, while all members of the research team will be involved in assessing methodological quality and the quality of measurement properties. This systematic review will adhere to the Consensus-based standards for the selection of health measurement instruments (COSMIN) guidelines for conducting systematic reviews of psychometric properties. We will provide summary tables of study characteristics and instrument characteristics used to measure health system literacy. Measurement properties and their quality will be assessed using the COSMIN standard criteria and the Grading of Recommendations, Assessment, Development and Evaluation (GRADE). We will also evaluate methodological quality of measurement properties using the COSMIN Risk of Bias checklist. ETHICS AND DISSEMINATION: This review does not collect original data, so obtaining ethical approval is not applicable. The findings will be disseminated through peer-reviewed journals, which can assist researchers and providers in choosing the appropriate instrument measuring health system literacy. PROSPERO REGISTRATION NUMBER: CRD420251004362.