Developments in the field of reliability and agreement studies: a methods review protocol

Introduction: The Guidelines for Reporting Reliability and Agreement Studies (GRRAS) were developed to improve the completeness and transparency of reporting of reliability and agreement of health measurement instruments. However, since their publication in 2011 methodological standards, both for reporting guideline development and reliability, agreement, and measurement error studies, have advanced, highlighting the need for aligning and updating. In addition, related initiatives like COnsensus-based Standards for the selection of health Measurement Instruments (COSMIN) have emerged, offering opportunities to harmonize terminology and promote consistency across diverse types of measurement instruments. This methods review aims (1) to systematically identify and synthesize commentaries on and evaluations of the original GRRAS, and (2) to map recent methodological developments in the planning, conduct, and interpretation of reliability, agreement and measurement error studies that should be reflected in the reporting and may imply or explicitly recommend updates, to inform the development of the GRRAS-COSMIN reporting guidelines. Methods and analysis: Two complementary search strategies will be employed. First, forward direct citation tracking of the original GRRAS publications will be conducted in Web of Science. We will include sources providing critique, commentaries, or suggestions related to the GRRAS. We will exclude publications that used GRRAS just for structuring their report, withdrawn or retracted articles, textbooks, peer reviews, supplements, and conference materials without full-text publications. Included articles will be analysed using descriptive content analysis. Second, we will perform a systematic search in Medline, PsycINFO, Embase, Eric, and Cinahl supplemented by key references identified by or known to the author team. We will include studies, reviews, commentaries, editorials, methodological papers, tutorials and guidance documents that discuss or critically reflect on methodological aspects of the measurement properties reliability and/or agreement/measurement error published between 01.01.2015 and 31.07.2025 in the field of health measurement research. Eligibility will be assessed by two independent reviewers and included sources will be analysed using ‘codebook’ thematic analysis. Findings will be presented narratively supplemented by visuals and tables if appropriate.Ethics and dissemination: This study involves publicly available data. No ethical approval is needed. Results will be disseminated through an open-access journal publication following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses-Scoping Review Extension and conference presentations.