Development and psychometric properties of the Japanese heart failure knowledge scale.

Knowledge about their own condition is important for patients with heart failure (HF). No valid, reliable, and easily administered instrument is available to measure this knowledge in clinical practice. In this study, a HF knowledge scale was developed, and its psychometric properties were tested. Items related to knowledge about HF were extracted from relevant guidelines. Content validity of the items was confirmed by an expert panel including a cardiologist and nurses specialized in treatment and care of patients with HF. A self-administered questionnaire was then distributed to 187 patients with HF (64.0 ± 12.1 years, males 69%). In 62% patients, a left ventricular ejection fraction of < 50% was identified. Exploratory factor analysis demonstrated the one-dimensionality of the 15-item HF knowledge scale. Mean score was 10.7 ± 3.0 (range, 0-15). Known-group validity testing revealed a significant difference in HF knowledge score between patients newly diagnosed with HF and patients experienced with HF (9.4 ± 3.2 versus 10.8 ± 2.9, P = 0.043). In addition, HF knowledge scale scores were correlated with HF self-care scores assessed by the European Heart Failure Self-Care Behavior Scale for evaluation of criterion validity (ρ = -0.304, P < 0.001). Cronbach's alpha was 0.79, and item-total correlation was 0.22-0.51, thereby suggesting that the reliability of the scale was acceptable. Acceptable validity and reliability were demonstrated for the HF knowledge scale developed in this study. This instrument could be useful in evaluation of patient knowledge about HF.