Importance: Improving patients' health status is a key goal of treating tricuspid regurgitation (TR). The Kansas City Cardiomyopathy Questionnaire (KCCQ) is a heart failure disease-specific health status measure used to capture the health status impact of TR and the benefit of transcatheter tricuspid valve intervention (TTVI), but its validity in this clinical setting is unknown., Objective: To evaluate the psychometric properties of the KCCQ in patients with TR., Design, Setting, and Participants: Data were pooled from patients with severe TR enrolled in 11 manufacturer-sponsored trials of TTVI. The data were transferred to the US Food and Drug Administration to harmonize and anonymize prior to analysis by an independent center. Data were collected from December 2015 to April 2023, and data analysis was performed from July to October 2023., Main Outcomes and Measures: Prespecified analyses included evaluation of internal consistency, reproducibility, responsiveness, construct validity, and predictive validity. Outcomes were determined using Cronbach α, score comparisons, intraclass correlation, Cohen d, Spearman correlations with best available reference measures, and association of scores and changes in scores with risk of subsequent clinical events., Results: The study cohort was composed of 2693 patients enrolled in either single-arm (n = 1517) or randomized (n = 1176) investigations of TTVI. Mean (SD) patient age was 78.6 (8.0) years, 1658 of 2693 patients (61.6%) were female, and the mean (SD) baseline KCCQ Overall Summary (KCCQ-OS) score was 50 (23). There was strong internal consistency within individual domains (Cronbach α, .77-.83). Among clinically stable patients between 1 and 6 months, there were small mean changes in KCCQ domain and summary scores (differences of -0.1 to 1.9 points), demonstrating reproducibility. In contrast, domain and summary scores of patients who underwent TTVI showed large improvements at 1 month after treatment (mean changes, 12.1-21.4 points), indicating excellent perceived responsiveness. Construct validity was moderately strong when domains were compared with best available reference measures (Spearman correlations, 0.47-0.69). In both cross-sectional and longitudinal analyses, the KCCQ-OS was associated with clinical events, with lower scores associated with an increased risk of mortality (hazard ratio, 1.34 per 10-point decrement; 95% CI, 1.22-1.47) and heart failure hospitalization (hazard ratio, 1.24 per 10-point decrement; 95% CI, 1.17-1.31)., Conclusions and Relevance: In this cohort study, the KCCQ had strong psychometric properties in patients with severe TR, including reliability, responsiveness, and validity. These data support use of the KCCQ in patients with severe TR as a measure of their symptoms, function, and quality of life and also for assessing the impact of interventions, such as TTVI, in rigorously controlled trials.