The current version of the Guidelines for Reporting Reliability and Agreement Studies (GRRAS) were published in 2011. Although the GRRAS are still widely applied, they are outdated compared to methodological developments regarding health research reporting guidelines in recent years. Substantial advances have been made regarding sample size determination and other aspects in reliability and agreement studies. In addition, the development of the current GRRAS did not follow the state-of-the-art guidance for developers of health research reporting guidelines, because that were not yet available at the time of GRRAS development. Therefore, an update of the GRRAS according to the current standards of reporting guideline development is needed.Additionally, this update aims to harmonize and align wordings and concepts with relavant related initiatives such as the COnsensus-based Standards for the selection of health Measurement Instruments (COSMIN), to improve usability and uptake of the-updated guidelines. Recently, COSMIN developed a tool to assess the risk of bias of reliability and agreement/measurement error studies and of systematic reviews of Patient-Reported Outcome Measures. Similarly, Lucas et al. published a quality appraisal tool for studies of diagnostic reliability (QAREL), which also applies to reliability and agreement studies. Although study reporting and risk of bias assessments are fundamentally different, both approaches should be harmonized. Only what is reported can be assessed. Therefore, reporting guidelines must contain the items for which the risk of bias is assessed.
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Registered: 18 June 2025
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Contact: Merle-Marie Pittelkow Email: [email protected]