Interrelationships Between Kansas City Cardiomyopathy Questionnaire Domains, Age, and Sex for Patients With Heart Failure: Findings From the CHAMP-HF and CORC Registries

BACKGROUND: Although Kansas City Cardiomyopathy Questionnaire (KCCQ) domains independently quantify patients’ symptoms, physical and social functioning, and quality of life, the interrelationships between domains (eg, symptoms impacting physical limitations) have not been described, nor whether these vary by age or sex. METHODS: Cross-sectional data from adult outpatients with heart failure and reduced ejection fraction from 2 multicenter US registries, the Change the Management of Patients With Heart Failure Registry (2015–2017) and Cardiovascular Outcomes Research Consortium (2001–2002), were used to fit recursive path analysis models relating age, sex, and KCCQ domain scores. The interrelationships of these factors were quantified using unstandardized and standardized effect estimates. Unstandardized effects denote the linear effect of the independent variable on the dependent variable in units specific to both variables. Standardized effects are unitless and are obtained by multiplying the unstandardized effect by the ratio of the standard deviations of the dependent and independent variables. RESULTS: The analytic cohorts included 4839 patients from the Change the Management of Patients With Heart Failure Registry (mean age, 66.1±12.5 years, 29.3% women) and 547 patients from the Cardiovascular Outcomes Research Consortium (mean age, 66±12 years, 23.8% women). Standardized effect estimates revealed moderate to strong interrelationships among the KCCQ domains (effect size range, 0.34–0.70). Symptoms were strongly associated with all other domains (range, 0.61–0.70). Quality of life was most associated with symptoms and social limitations (range: 0.48–0.60), and less so with physical limitations (effect size=0.34). By comparison, the associations of age and sex with KCCQ domains were much smaller (effect sizes <0.2), and no interactions by age and sex were found. CONCLUSIONS: KCCQ domains were strongly interrelated, and these relationships did not differ appreciably by age or sex. These data enhance the interpretation of KCCQ domain scores in research and clinical practice; in particular, symptoms and social limitations may be key drivers of impaired quality of life in heart failure. Targeted interventions prioritizing these domains may most effectively improve patients’ overall health status.