Protocol for the development of a core outcome set for lateral elbow tendinopathy (COS-LET)

BACKGROUND: Lateral elbow tendinopathy (LET) is a common condition that can cause significant disability and associated socioeconomic cost. Although it has been widely researched, outcome measures are highly variable which restricts evidence synthesis across studies. In 2019, a working group of international experts, health care professionals and patients, in the field of tendinopathy (International Scientific Tendinopathy Symposium Consensus (ICON) Group), published the results of a consensus exercise defining the nine core domains that should be measured in tendinopathy research. The aim of this study is to develop a core outcome set (COS) for LET mapping to these core domains. The primary output will provide a template for future outcome evaluation of LET. In this protocol, we detail the methodological approach to the COS-LET development. METHODS: This study will employ a three-phase approach. (1) A systematic review of studies investigating LET will produce a comprehensive list of all instruments currently employed to quantify the treatment effect or outcome. (2) Instruments will be matched to the list of nine core tendinopathy outcome domains by a Steering Committee of clinicians and researchers with a specialist interest in LET resulting in a set of candidate instruments. (3) An international three-stage Delphi study will be conducted involving experienced clinicians, researchers and patients. Within this Delphi study, candidate instruments will be selected based upon screening using the Outcome Measures in Rheumatology (OMERACT) truth, feasibility and discrimination filters with a threshold of 70% agreement set for consensus. CONCLUSIONS: There is currently no COS for the measurement or monitoring of LET in trials or clinical practice. The output from this project will be a minimum COS recommended for use in all future English language studies related to LET. The findings will be published in a high-quality journal and disseminated widely using professional networks, social media and via presentation at international conferences. TRIAL REGISTRATION: Registered with the Core Outcome Measures in Effectiveness Trials (COMET) database, November 2019. https://www.comet-initiative.org/Studies/Details/1497.