Development and validation of a Quality of Life and Treatment Satisfaction measure in feline osteoarthritis.

INTRODUCTION: Osteoarthritis (OA) in cats causes pain and mobility impairment, negatively impacting quality of life (QoL) of cats and their owners. Owner-perceived treatment satisfaction can influence treatment adherence and subsequent health outcomes for the cat. Currently, no OA-specific instrument for cats assesses all three concepts. This study aimed to address this gap by developing and psychometrically evaluating an owner-completed feline OA-specific measure-the "Feline OA Quality of Life and Treatment Satisfaction Assessment" (FeOA-QoL-TS-A)-to measure cat QoL, owner QoL, and owner treatment satisfaction. METHODS: A mixed-methods approach was used. The draft FeOA-QoL-TS-A was developed using a conceptual model derived from an earlier meta-synthesis of published literature and supplementary review. Qualitative interviews were then conducted with eight owners of cats with OA to evaluate the content validity of the draft FeOA-QoL-TS-A. The revised FeOA-QoL-TS-A was then administered to owners of OA-treated cats (n = 139) at six timepoints during a phase 4 field study to evaluate the psychometric properties of the resulting item-scale structure. RESULTS: Interview findings informed revisions to the draft 25-item FeOA-QoL-TS-A, which was well understood by owners. Item-level analysis and confirmatory factor analysis supported the removal of five items and confirmed the structure of three distinct domains: Cat QoL, Owner QoL, and Treatment Satisfaction. The final 20-item FeOA-QoL-TS-A demonstrated good internal consistency and test-retest reliability. Convergent validity was supported by strong correlations with concurrent measures. Known groups comparisons provided strong evidence that the instrument can differentiate between groups with varying QoL levels. Ability to detect improvement in Cat and Owner QoL domains was demonstrated through statistically significant improvements over time, with larger effect sizes reported for the 'improved' group compared with the 'stable' group. Anchor-based analyses supported -1.0 and -0.9-point responder definitions for Cat and Owner QoL domains, respectively. CONCLUSION: The final 20-item FeOA-QoL-TS-A is a valid, reliable, and responsive instrument for assessing OA-specific cat QoL, owner QoL, and treatment satisfaction. Its flexible domain structure supports application in veterinary practice, stakeholder communications, and clinical research endpoints. The FeOA-QoL-TS-A addresses a critical measurement gap by providing a comprehensive and practical solution to evaluate the multifaceted impacts of feline OA.