Let me introduce you to TENDINS-AT: A new patient reported outcome measure to assess the severity of disability in Achilles tendinopathy

Introduction: Existing patient-reported outcome measures (PROMs) for Achilles tendinopathy [e.g., Victorian Institute of Sport Assessment (VISA)] have been heavily criticised for the lack of patient involvement in their development, meaning their outcomes are unlikely to be patient-focussed. Our objectives were: 1) collate perceptions and experience of patients/ professionals to develop a new PROM assessing the severity of Achilles tendinopathy disability, and 2) determine the content validity (relevance, comprehensiveness and comprehensibility) of the PROM developed. Methods: We performed a mixed-methods study following Consensus-based Standards for the selection of health Measurement Instruments (COSMIN) guidelines. This incorporated one round of semi-structured, one-on-one interview responses with patients/ professionals, for initial item generation. Followed by one round of survey responses for professionals and a final round of semi-structured, one-on-one interviews with patients, satisfying COSMIN guidelines for adequate patient/ professional involvement. Participants identified three sub-domains contributing to Achilles tendinopathy disability severity: pain, symptoms, and functional capacity. Thus, this study has developed a PROM to quantify Achilles tendinopathy severity under the ICON tendinopathy core health domain of disability: the TENDINS-AT. Results: All eight patients invited to participate were enrolled. Forty professionals (50% women, six different continents) were invited to participate and 30 were enrolled (75% response rate). Professional participants were predominantly men (57%) with ages ranging from 28-67 years. The professional group included twenty-two researchers, four orthopaedic surgeons, four sports physicians, four physiotherapists, two PROM experts, one podiatrist and one general practitioner (some selecting two professions). Geographical affiliation of professionals varied with twelve from Australia, four from the United Kingdom, three each from the United States of America, South Africa and Sweden, two from New Zealand and one each from Denmark, Ireland and the Netherlands. Following three rounds of qualitative or quantitative feedback, this study has established the content validity of the TENDINS-AT (good relevance, comprehensibility and comprehensiveness). Therefore, the TENDINS-AT is the only Achilles tendinopathy PROM measuring the severity of disability (including pain, symptoms and functional capacity) to have good content validity. Discussion: The TENDINS-AT should now be encouraged for use in clinical and research populations, in conjunction with existing PROMs, given its established content validity. However, caution should be taken in the interpretation of results from the TENDINS-AT until further testing to establish the most appropriate scoring scale, reliability, construct validity, criterion validity and responsiveness of the TENDINS-AT has been established. Impact/Application to the field: This study, based on the feedback from participants, found that a single tool to assess Achilles tendinopathy disability is preferred to separate tools to assess insertional and mid-portion Achilles tendinopathy or for separate tools for physically active and sedentary people. This would also be likely to reduce barriers associated with assessment by simplifying the process for clinicians, as they are not having to provide different PROMs for different patient demographics. However, a future Rasch analysis will assess whether this is appropriate by determining whether the TENDINS-AT score is influenced by the region of Achilles tendinopathy and other factors (e.g., ceiling and floor effects) identified within the original VISA-A. Declaration: My co-authors and I acknowledge that we have no conflict of interest of relevance to the submission of this abstract.