Development of measure for disease-specific quality of life in patients with chronic heart failure

Objectives. To develop a measure for disease-specific health-related quality of life in patients with heart failure and examine its reliability and validity. Methods. One hundred and four patients with stable chronic heart failure (74 males, 30 females, mean age 64.2 ± 10.0 years) with left ventricular ejection fractions of less than 40% were enrolled in this study. Each patient responded to the Medical Outcomes Study Short Form 36 (SF-36) and a disease specific questionnaire comprising four categories (dyspnea, sleep, appetite and fatigue), each consisting of five to six questions. A stepwise exploratory factor analysis was applied to the disease-specific measure to consider categorical fitness. In 25 of the 104 patients, the data in the questionnaire were compared with peak oxygen uptake, anaerobic threshold, slope of the regression line relating the ventilatory equivalent to carbon dioxide output (V̇_E/V̇_CO2 slope) and peak work rate. Correlations between the questionnaire and eight components of SF-36 were evaluated. Results. The appetite category proved unreliable and was excluded from consideration, so 12 questions were adopted from the other three categories. Cronbach's a values ranged from 0.68 to 0.89 and the coefficients of test-retest were from 0.84 to 0.94, so both internal consistency and reproducibility of these questions were considered excellent. The scores of three categories well reflected the severity of heart failure based in New York Heart Association functional class. The anaerobic threshold (r = 0.53), peak oxygen uptake (r = 0.66), V̇E/V̇_CO2 slope (r = -0.48) and peak work rate (r = 0.41) correlated with the total score of the 12 questions. The total scores were closely correlated with the eight components of SF-36. Conclusions. This study suggests that the disease-specific questionnaire is applicable to evaluation of the health-related quality of life in patients with heart failure.