Ensuring face validity in patient-related outcome scores - A matter of content

Patient reported outcome (PRO) questionnaires are increasingly used to measure treatment effect in patients with knee pathology. PROs commonly used to assess outcome in patients with knee conditions can be generic, knee-specific, or condition-specific. Most PROs have been created based on clinician-based consensus and are not patient-centered. Items (questions plus their response options) in PROs can be generated by clinicians or through patient interviews. Items created by clinicians possess face validity. The objective of this study was to find all existing PRO items with potentially relevant content for patients with knee pathology.