Abstract
A recent COSMIN review found that the Victorian Institute of Sports Assessment-Achilles tendinopathy questionnaire (VISA-A) has flawed construct validity. The objective of the current study was to assess specifically the process of how VISA-A was constructed and validated, and whether the Danish version of VISA-A is a valid patient-reported outcome measure (PROM) for measuring the perceived impact of Achilles tendinopathy. The original item generation strategy for content validity and the process for confirming the scaling properties (construct validity) were examined. In addition, construct validity was evaluated directly using several psychometric methods (Rasch analysis, confirmatory factor analysis (CFA), and multivariable linear regression) in a cohort of 318 persons with Achilles tendinopathy with symptom duration groups ranging from less than 3 months to more than 1 year of chronicity, and a group of 120 healthy persons. We found that the item generation and item reduction in the original construction of VISA-A was based on literature review and clinician consensus with little or no patient involvement. We determined that 1) VISA-A consists of ambiguous conceptual item themes and thus lacks content validity, 2) there was no thorough investigation of the psychometric properties of the original version of VISA-A, which thus lacks construct validity, and 3) rigorous direct assessment of the psychometric properties of the Danish VISA-A revealed inadequate psychometric properties. In agreement with the COSMIN study, we conclude that when used as a single score, VISA-A is not an adequate scale for measuring self-reported impact of Achilles tendinopathy.