Outcomes, health policy, and managed care: Relationships between patient-reported outcome measures and clinical measures in outpatients with heart failure

Background Patient-reported outcomes are increasingly used to assess the efficacy of new treatments. Understanding relationships between these and clinical measures can facilitate their interpretation. We examined associations between patient-reported measures of health-related quality of life and clinical indicators of disease severity in a large, heterogeneous sample of patients with heart failure. Methods Patient-reported measures, including the Kansas City Cardiomyopathy Questionnaire (KCCQ) and the EuroQol Visual Analog Scale (VAS), and clinical measures, including peak VO2, 6-minute walk distance, and New York Heart Association (NYHA) class, were assessed at baseline in 233 1 patients with heart failure. We used general linear models to regress patient-reported measures on each clinical measure. Final models included for significant sociodemographic variables and 2-way interactions. Results The KCCQ was correlated with peak VO2 (r=.21) and 6-minute walk distance (r=.27). The VAS was correlated with peak VO2 (r=.09) and 6-minute walk distance (r=.11). Using the KCCQ as the response variable, a 1-SD difference in peak VO2 (4.7 mL/kg/min) was associated with a 2.86-point difference in the VAS (95% Cl, 1.98-3.74) and a 4.75-point difference in the KCCQ (95% Cl, 3.78-5.72). A 1-SD difference in 6-minute walk distance (105 m) was associated with a 2.78-point difference in the VAS (95% Cl, 1.92-3.64) and a 5.92-point difference in the KCCQ (95% Cl, 4.98-6.87); NYHA class III was associated with an 8.26-point lower VAS (95% Cl, 6.59-9.93) and a 12.73-point lower KCCQ (95% Cl, 10.92-14.53) than NYHA class II. Conclusions These data may inform deliberations about how to best measure benefits of heart failure interventions, and they generally support the practice of considering a 5-point difference on the KCCQ and a 3-point difference on the VAS to be clinically meaningful. (Am Heart J 2009;158:S64-S71.)