TENDINopathy Severity assessment - Achilles (TENDINS-A): Development and Content Validity assessment of a new Patient-Reported Outcome Measure for Achilles Tendinopathy

OBJECTIVE: To develop a new patient-reported outcome measure (PROM) assessing TENDINopathy Severity of the Achilles (TENDINS-Achilles) and evaluate its content validity.

DESIGN: Mixed-methods, modified Delphi.

METHODS: We performed 1 round of semistructured one-on-one interview responses with professionals and patients, for initial item generation. This was followed by 1 round of survey responses for professionals and a final round of semistructured one-on-one interviews with patients. The work culminated in a PROM to quantify Achilles tendinopathy severity under the core health domain of disability. Participants identified 3 subdomains contributing to the severity of disability of Achilles tendinopathy: pain, symptoms, and functional capacity.

RESULTS: All 8 patient participants invited to participate were enrolled. Forty professional participants (50% women, six different continents) were invited to participate and 30 were enrolled (75% response rate). Therefore, a total of 30 professionals and 8 patients were included within this study. Following 3 rounds of qualitative or quantitative feedback, this study has established the content validity of TENDINS-A (good relevance, comprehensibility, and comprehensiveness) as a new PROM to assess the severity of Achilles tendinopathy, which assesses aspects of pain, symptoms, and functional capacity.

CONCLUSION: TENDINS-A has established content validity and is appropriate for use with clinical and research populations. We recommend users interpret TENDINS-A results cautiously, until further testing evaluates the most appropriate scoring scale, reliability, construct validity, criterion validity, and responsiveness of TENDINS-A. Until these psychometric properties are established, we suggest using TENDINS-A alongside existing tools.