A scale for measuring home-based cardiac rehabilitation exercise adherence: a development and validation study

BACKGROUND: The benefits of home-based cardiac rehabilitation exercise are well-established and depend on long-term adherence. However, there is no uniform and recognized cardiac rehabilitation criterion to assess home-based cardiac rehabilitation exercise adherence for patients with cardiovascular disease. This study aimed to develop a home-based cardiac rehabilitation exercise adherence scale and to validate its psychometric properties among patients with chronic heart failure. METHODS: The dimensions and items of the scale were created based on grounded theory research, literature content analysis, and defined by a Delphi survey. Item analysis was completed to assess the discrimination and homogeneity of the scale. Factor analysis was adopted to explore and validate the underlying factor structure of the scale. Content validity and calibration validity were evaluated using the Delphi survey and correlation analysis, respectively. Reliability was evaluated by Cronbach's α coefficients, split-half reliability coefficients, and test-retest reliability coefficients. RESULTS: A scale covering four dimensions and 20 items was developed for evaluating home-based cardiac rehabilitation exercise adherence. The content validity index of the scale was 0.986. In exploratory factor analysis, a four-factor structure model was confirmed, explaining 75.1% of the total variation. In confirmatory factor analysis, the four-factor structure was supported by the appropriate fitting indexes. Calibration validity of the scale was 0.726. In terms of reliability, the Cronbach's α coefficient of the scale was 0.894, and the Cronbach's α coefficients of dimensions ranged from 0.848 to 0.914. The split-half reliability coefficient of the scale was 0.695. The test-retest reliability coefficient of the scale was 0.745. CONCLUSION: In this study, a home-based cardiac rehabilitation exercise adherence scale was developed and its appropriate psychometric properties were confirmed.