Study design
A cross-sectional validation design was adopted in this study. We contacted the original author of the scale, Professor Kim, to obtain authorization and consent [16]. The Brislin principle of translation (forward-translation, back-translation, acculturation) was adopted [17].
Development of the Chinese version of CADES
Scale translation
After obtaining permission from the author of the English CADES, the translation process was shown in Fig. 1.
Cross-cultural adaptation
According to the equivalence model first proposed by Flaherty et al. in 1988 [18], seven experts from the fields of clinical nursing, nursing management, psychology, and medicine were invited to further modify and polish the scale from five aspects: content, semantic, technical, criterion, and conceptual equivalence to ensure the cross-cultural validity. The research group sorted out the opinions of seven experts, and the pretest version CADES-2 was finally formed after discussion and modification. The criteria for expert selection were as follows: bachelor’s degree or above, intermediate or above professional title, and five years of working experience in related fields.
Pretest
In September 2022, 30 patients with CAD who were hospitalized in the department of cardiology of a hospital were investigated in advance to evaluate whether the language expression of the scale was clear and easy to understand and to adjust the language expression of items according to patient feedback [19].
Subjects
In this study, the convenience sampling method was employed to conduct a questionnaire survey among patients in the first affiliated hospital of a university who met the inclusion and exclusion criteria from September 2022 to June 2023. The inclusion criteria were: (1) met the diagnostic of CAD with a duration of at least 3 months; (2) admission for PCI; (3) age between 18 and 75 years, with the ability to understand questions; (4) fluency in spoken or written Chinese; (5) stable disease statue (no recent exacerbations); and (6) informed consent and voluntary participation. The exclusion criteria were: (1) a history of other serious life-threatening conditions (such as advanced-stage cancer, end-stage organ failure, severe respiratory disorders, or advanced neurological disorders); and (2) mental disorders or cognitive impairment.
Data collection occurred in two phases. The first stage focused on item analysis and exploratory factor analysis. The sample size should be 5–10 times that of the questionnaire items, and our questionnaire contains 25 items [20]. The study’s sample size was 5 times the items, and the required sample size was at least 147 cases. Our study achieved a sample size of 185 participants, with 180 valid questionnaires and an effective rate of 97.30%. For confirmatory factor analysis, a minimum sample size of 200 cases is generally required [21]. In the second stage, 215 people were surveyed, with 211 valid questionnaires and an effective rate of 98.14%.
Instruments
All participants completed the Chinese versions of the CADES and the Chinese version of General Self-Efficacy Scale (C-GSES). In addition, participants provided general profile information, including sociodemographic and clinical variables related to CAD, such as sex, age, marital status, education level, and disease duration.
Chinese version of the GSES
The GSES developed by Schwarzer et al. was widely used in many countries to measure an individual’s confidence in their ability to cope with a wide range of stressful or challenging demands [22]. The GSES has been translated into Chinese, and the C-GSES has demonstrated good reliability with Cronbach’s alpha of 0.91 [23]. The C-GSES consists of 10 items with a unidimensional factor structure. Each statement is measured on a four-point likert scale, ranging from 1 (always false) to 4 (always true). The sum of the item scores was the general self-efficacy score, with total scores ranging from 10 to 40. Higher scores indicate greater self-efficacy.
Chinese version of the CADES
The CADES was used to assess empowerment in patients with CAD in Korea [16]. The scale consisted of 25 items, including self-determination, emotional self-regulation, and personal competence of disease management perception. The degree of agreement with each item was expressed on a five-point ordinal scale (from 1 = strongly disagree to 5 = strongly agree). The total score ranged from 25 to 125 points. The higher the score, the higher the degree of empowerment. The Cronbach’s α coefficient of the English scale was 0.89–0.93, and it had good reliability and validity.
Data collection
The data collection period for this study spanned from September 2022 to June 2023. The study received approval from the Ethics Committee of the First Affiliated Hospital, College of Medicine, Zhejiang University (IIT20220341B-R1). Following this, the research coordinator presented the study to the head nurses of the hospital wards. Upon receiving their approval, patients who met the inclusion criteria and were willing to participate were asked to sign informed consent forms and complete a short questionnaire.
All the investigators were members of this research group, familiar with the research topic, and trained in the questionnaire administration method. The questionnaires were distributed to patients on the day of discharge. Investigators were available to assist patients with any questions or doubts during the process of completing the survey. All questionnaires were distributed and collected on the spot, and the data were sorted out in time to eliminate invalid questionnaires. A total of 400 scales were distributed, with 391 responses received, and the effective completion rate was 97.75%. The average time to finish the survey was about 5–6 min.
Reliability and validity test method
Item analysis
In this study, the critical ratio method and item-total score correlation method were used for item analysis: (1) Critical ratio (CR) method: the top 27% and bottom 27% of the total scale scores represented the high and low groups, respectively. An independent sample t-test was used to compare the differences between these groups for each item. Items with no statistical significance (P ≥ 0.05) or CR values < 3 were deleted [24]. (2) Item-total score correlation method: the correlation coefficient between each item and the total scale score was assessed through correlation analysis. Items with correlation coefficients < 0.3 or not reaching the significance level (P ≥ 0.05) were deleted [25].
Validity analysis
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(1)
The Content Validity Index was calculated based on expert opinions, including the item-level content validity index (I-CVI) and the scale-level content validity index (S-CVI). Seven experts rated the correlation between each item and its dimension of the Chinese CADES on a scale of 1 to 4 (1 = not related, 2 = weak correlation, 3 = more relevant, and 4 = very relevant). I-CVI ≥ 0.78 and S-CVI ≥ 0.90 were considered acceptable [26]. (2) Exploratory factor analysis and confirmatory factor analysis were conducted to assess construct validity. The Kaiser-Meyer-Olkin (KMO) test (KMO > 0.60) and Bartlett’s χ2 test (P < 0.05) were used to determine the suitability for factor analysis. Factors with eigenvalues > 1 were extracted, and the cumulative variance contribution rate was calculated. Items with factor loadings < 0.4 or double loadings were deleted [27]. Confirmatory factor analysis was used to examine the factor model, evaluating the model fit with the χ2 degree of freedom ratio (χ2/df), Tucker-Lewis index (TLI), comparative fit index (CFI), incremental fit index (IFI), and root mean square error of approximation (RMSEA) [28]. (3) For criterion-related validity, the correlation between the Chinese CADES and the C-GSES was calculated using Pearson’s correlation analysis.
Reliability analysis
(1) Internal consistency referred to the homogeneity and internal correlation among all items in the scale, which were assessed using Cronbach’s alpha coefficient. A score greater than or equal to 0.6 was considered acceptable [29]. (2) Split-half reliability was determined by calculating Guttman’s split-half coefficient, with its coefficient over 0.70 being considered satisfactory [30]. (3) The reliability of test scores was analyzed by computing McDonald’s omega coefficient, considering values of 0.7 or higher as satisfactory [31].
Statistical analysis
IBM SPSS software version 25.0 and AMOS software version 28.0 were used for the statistical analysis. Data are presented as the mean ± standard deviation for continuous variables or as N (%) for categorical variables. Item analysis was performed using the critical ratio method and correlation coefficient method. Content validity was determined based on expert ratings of the items. Exploratory factor analysis and confirmatory factor analysis were utilized to validate the structural integrity of the scale. Pearson’s correlation between the Chinese CADES and C-GSES scores was calculated to determine criterion-related validity. The reliability of the scale was evaluated using Cronbach’s alpha coefficient, split-half coefficient, and McDonald’s omega coefficient.
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