An update on the self-care of heart failure index

Abstract

Background: The Self-care of Heart Failure Index (SCHFI) is a measure of self-care defined as a naturalistic decision-making process involving the choice of behaviors that maintain physiological stability (maintenance) and the response to symptoms when they occur (management). In the 5 years since the SCHFI was published, we have added items, refined the response format of the maintenance scale and the SCHFI scoring procedure, and modified our advice about how to use the scores.

Objective: The objective of this article was to update users on these changes.

Methods: In this article, we address 8 specific questions about reliability, item difficulty, frequency of administration, learning effects, social desirability, validity, judgments of self-care adequacy, clinically relevant change, and comparability of the various versions.

Results: The addition of items to the self-care maintenance scale did not significantly change the coefficient alpha, providing evidence that the structure of the instrument is more powerful than the individual items. No learning effect is associated with repeated administration. Social desirability is minimal. More evidence is provided of the validity of the SCHFI. A score of 70 or greater can be used as the cut-point to judge self-care adequacy, although evidence is provided that benefit occurs at even lower levels of self-care. A change in a scale score more than one-half of an SD is considered clinically relevant. Because of the standardized scores, results obtained with prior versions can be compared with those from later versions.

Conclusion: The SCHFI v.6 is ready to be used by investigators. By publication in this format, we are putting the instrument in the public domain; permission is not required to use the SCHFI.

Figure 1. Model Illustrating the Process of Heart Failure Self-Care

Heart failure self-care is conceptualized as a process involving maintenance and management. Patients perform self-care maintenance behaviors such as medication adherence to keep themselves physiologically stable. Self-care management is performed when a heart failure symptom occurs. The patient must recognize the symptom as related to heart failure, evaluate the importance of the symptom, do something about it, and then evaluate whether or not the treatment was effective. Self-care confidence is not a part of the self-care process per se; it is an extremely important factor influencing the effectiveness of self-care. Thus, it is included in the model.

Figure 2

Graphic representation of the confirmatory factor analysis. The figure displays the standardized loadings for the indicators of the SCHFI latent constructs self-care maintenance, self-care management, and self-care confidence. Numbers in the outlined boxes represent the SCHFI item numbers. The standardized numbers reflect the strength of the relationship between each indicator and the construct on which it loads. Abbreviations: CFI = comparative fit index, NFI = normed fit index, RMSEA = root mean square error of approximation.

Figure 3. Comparison of Prior and Current Scoring Algorithms

Comparative self-care maintenance scale scores shown as an example. Although the linear correlation between old standardized 25–100 SCHFI scale scores and new standardized 0–100 SCHFI scale scores is 1 (perfect linear correlation), there are a few key differences. With the new scoring algorithm, the average SCHFI scale scores will be lower overall, a lower proportion of patients will meet the ≥70 (adequate self-care) cut-point, and the dispersion of scores will be greater. For example using the same raw data, old standardized 25–100 scores have a mean and standard deviation of 70.23 ± 17.68, while the new standardized 0–100 scores have a mean of 60.29 ± 23.56. SCHFI = Self-Care of Heart Failure Index