Psychometric Testing of the Self-Care of Coronary Heart Disease Inventory Version 3.0 : Journal of Cardiovascular Nursing

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Psychometric Testing of the Self-Care of Coronary Heart Disease Inventory Version 3.0

Dickson, Victoria Vaughan PhD, CRNP, RN, FAAN; Iovino, Paolo PhD, RN; De Maria, Maddalena PhD, MSc, RN; Vellone, Ercole PhD, RN, FESC, FAAN; Alvaro, Rosaria MSN, RN; Di Matteo, Roberta MSN, RN; Dal Molin, Alberto PhD, MSN, RN; Lusignani, Maura MSc, RN; Bassola, Barbara PhD, MSc, RN; Maconi, Antonio MD; Bolgeo, Tatiana PhD, MSc, RN; Riegel, Barbara PhD, RN, FAAN

Author Information
The Journal of Cardiovascular Nursing ():10.1097/JCN.0000000000000952, October 24, 2022. | DOI: 10.1097/JCN.0000000000000952
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Abstract

Worldwide, coronary heart disease (CHD) is a leading cause of morbidity and mortality.1 In the United States, 1 in 3 adults has CHD,1 and in Europe, 45% of deaths are related to cardiovascular disease.2,3 Advances in medical and surgical management of CHD have improved many patient outcomes including mortality rates. However, individuals with CHD remain at an increased risk for unstable angina, myocardial infarction, and heart failure.1 Self-care is an essential component of the daily management of CHD, with the need to practice behaviors that maintain physiological and emotional stability, monitor symptoms, and manage symptoms that occur. Stability is maintained with adherence to the recommended diet, exercise, medication regimen, and stress management. Symptoms of chest pain, fatigue, and shortness of breath are common, but monitoring for them and managing them early can avoid emergency care and hospitalization.4 Availability of an instrument that measures all 3 elements of self-care maintenance, monitoring, and management can assist investigators and clinicians to identify where in the self-care process patients are struggling.

We developed the original Self-Care of Coronary Heart Disease Inventory (SC-CHDI) based on clinical guidelines and standards of care for CHD.5 The theory underlying the SC-CHDI, the theory of self-care of chronic illness,6 was updated in 2019 to emphasize the important contribution of symptoms to the process of self-care. In the earlier version of this instrument, the SC-CHDI v2, discussed further hereinafter, self-care monitoring behaviors were captured in the self-care maintenance and management scales. In this revision, a separate self-care monitoring scale is included, creating 3 distinct scales. Self-care confidence was measured within the SC-CHDI v2, but confidence is not part of self-care per se but something that greatly influences self-care. Thus, the confidence scale was removed and revised to reflect self-efficacy.7 We recommend that the Self-Care Self-Efficacy Scale be used routinely in conjunction with the SC-CHDI v3.

The SC-CHDI v2 has been translated and validated in several languages (www.self-care-measures.com) and is used widely in Europe, the United States, China, and South America to assess self-care. The SC-CHDI v2 has acceptable psychometric properties.8 Content validity was verified by a panel of 5 experts in cardiovascular nursing. The content validity index,9 calculated for each item and the entire instrument, was excellent (1.00). In a sample of 392 adults with CHD, factorial validity was supported with confirmatory factor analysis (CFA). The 10-item self-care maintenance scale included 2 dimensions: “consulting behaviors” (eg, taking medicines as prescribed) and “autonomous behaviors” (eg, exercising 30 min/d) (Factor Determinancy Score = 0.87). The 6-item self-care management scale also included 2 dimensions: “early recognition and response” (eg, recognizing symptoms) and “delayed response” (eg, change your activity level) (Factor Determinancy Score = 0.76).8 Convergent validity was supported with the Medical Outcomes Study Specific Adherence Scale10 and the Decision Making Competency Inventory.11 In psychometric testing in other countries, the self-care maintenance, management, and confidence scales have had similar reliability and factor structure results.12,13 The purpose of this study was to evaluate the psychometric properties of the updated SC-CHDI v3.

Instrument Revision

On the basis of the theory of self-care of chronic illness,14 instrument items were updated using recent research and clinical guidelines15,16 and reorganized and expanded to reflect the theoretical concepts of self-care maintenance, monitoring, and management. In the self-care maintenance scale, we added 2 items measuring behaviors that maintain health. Item 2 was added to ask how routinely something is done to relieve stress (eg, meditation, yoga, music). There is a growing appreciation for the direct and indirect effects of stress on cardiovascular health and the importance of managing daily stress,17 and compelling evidence on the effectiveness of stress reduction in CHD secondary prevention.18,19 We also added item 7 (“Try to avoid getting sick…”) based on existing guidelines recommending that individuals with CHD receive routine immunizations (eg, annual flu shot, pneumonia vaccine).15,20 In the recent pandemic, the high rates of COVID-19 hospitalizations and deaths among individuals with underlying cardiovascular conditions21,22 highlight the importance of this new self-care maintenance behavior.

We revised 3 questions to assess self-care maintenance behaviors more precisely. Item 1 regarding healthcare appointments with a doctor or nurse was revised to be more general to reflect the broader healthcare team that may include other provider types. To assess medication adherence more precisely, we combined 2 questions regarding taking medications as prescribed and using a reminder system into 1 question; item 5 is now “Take prescribed medicines without missing a dose.” Regular exercise is important for cardiovascular health; however, many individuals with CHD may be restricted from vigorous or moderately vigorous exercise, which was assessed in the previous version. The revised item 4 now captures recommendations for physical activity over sedentary behavior by assessing how routinely individuals engage in physical activity rather than structured, timed exercise. We removed the weight management questions because this item presumed that patients are overweight or obese, and the other items regarding healthy eating, exercise, and stress management are also weight management behaviors. In addition, blood pressure monitoring behavior was moved to the new self-care monitoring scale.

In summary, the self-care maintenance scale now includes 9 common adherence behaviors recommended for CHD (Table 1). The scale was also revised from a 4-point Likert scale to a 5-point scale (1, never or rarely, to 5, always or daily).

TABLE 1 - Sociodemographic and Clinical Characteristics of Participants (N = 205)
Mean (±SD)
Age, y 65.3 (11.1)
No. daily medications 6.2 (3.1)
Illness duration, mo 31.2 (68.5)
No. stents 2.1 (1.1)
No. comorbid conditions (CCI) 1.5 (1.5)a
n (%)
Gender
 Male 162 (79.0)
Marital status
 Married 127 (62.0)
Occupation
 Retired 111 (54.1)
Financial situation
 Make ends meet with some or plenty of difficulty 84 (41.0)
Education
 No formal education 1 (0.5)
 Elementary school 31 (15.1)
 Middle school 65 (31.7)
 High school 80 (39.0)
 University or higher 27 (13.2)
Comorbidity category (CCI)
 Low (≤2) 174 (84.9)
 Moderate (3–4) 23 (11.2)
 High (≥5) 8 (3.9)
Abbreviation: CCI, Charlson Comorbidity Index.
aRange, 0–10.

The new self-care monitoring scale assessing the practice of routine, vigilant body monitoring, and surveillance is intended to identify significant changes in physical or emotional health.14 For individuals with CHD, these 7 behaviors reflect actions that can be taken to assess a change in cardiovascular status.23 Responses are captured in a 5-point Likert scale (1, never or rarely, to 5, always or daily).

Symptom recognition is assessed by a single item that asks about the last time an individual had a symptom of CHD and how quickly they recognized it as a heart symptom. Respondents are provided a list of common symptoms (eg, chest pain, shortness of breath); response options include “I did not recognize it” (scored as 0) if not recognized and a 5-point Likert scale of 1 (not quickly) to 5 (very quickly). Previously, this item was analyzed as part of self-care management rather than self-care maintenance. Research with other self-care instruments has led us to realize that the recognition of symptoms is not conceptually part of self-care maintenance, self-care monitoring, or self-care management.24 Thus, we recommend that this item be scored separately. Scoring is discussed further hereinafter.

The self-care management scale assesses management of signs and symptoms and effectiveness of action taken. This scale asks how likely one is to try 1 of 5 actions if symptoms arise. Item 20 was reworded to reflect the action to “take medication to make the symptom decrease or go away”; this allows the respondent to answer regarding nitroglycerin if ordered or another medication that may be prescribed. We also added item 22 (talk to your healthcare provider at the next visit) in addition to calling one's healthcare provider when experiencing a symptom. These items reflect the naturalistic decision-making process on which self-care is based in which individuals assess the symptom experience and determine the sense of urgency in taking action.14 It is noteworthy that, in revising the SC-CHDI v3.0, we kept the self-care management item “take an aspirin,” although the evidence for routine daily aspirin as a primary preventative guideline is under review.25 We kept it because taking an aspirin when experiencing chest pain is still endorsed in clinical guidelines.15 The final item on the self-care management scale, unchanged from the previous version, reflects evaluation of the effectiveness of self-care management behaviors. The response scale was revised from a 4-point Likert scale to a 5-point scale (1, not likely, to 5, very likely).

The scoring instructions for the SC-CHDI v3.0 are similar to that of the other self-care instruments. As the instrument is an inventory made up of 3 separate scales, a standardized score is computed separately for each individual scale; there is no total score. To compute a standardized score, a raw scale score is first computed and then transformed to a standardized score that ranges from 0 to 100. With standardized scores, you do not need to impute missing values; if ≥50% of the items in each multi-item scale (eg, self-care maintenance, monitoring, and management) are answered, you can calculate a scale score. Otherwise, the score for that scale should be considered missing. Do not add the single item assessing recognition of symptoms to any of the scales. Instead, compute a percentage reflecting the percentage of people in the various symptom recognition groups. For example, you might report the percentage of respondents stating that they recognized their symptom very quickly. Detailed instructions for instrument scoring found at https://self-care-measures.com/self-care-scoring-algorithm/.

Methods

This was a secondary analysis of baseline data from an ongoing Italian longitudinal study “Self-Care in Coronary Heart Disease Patient and Caregiver Dyads (HEARTS-IN-DYADS).” The aim of that study was to describe self-care in patients with CHD. To examine the psychometric properties of the SC-CHDI v3.0, we analyzed the data collected from the first 205 enrolled adults with a confirmed diagnosis of CHD. The HEARTS-IN-DYADS study is conducted in accordance with the Helsinki Declaration26 and was approved by the ethical committees of each participating center.

Sample

A convenience sample of adults (age ≥ 18 years) was recruited from 5 cardiovascular centers in northern and central Italy (Alessandria, Milan, Novara, Reggio Emilia, and Rome). Individuals were eligible to participate if they had a diagnosis of CHD confirmed with cardiac catheterization, were deemed clinically stable, and were able to understand spoken and written Italian. Individuals were excluded if they had other serious cardiac diseases (eg, heart failure, cardiomyopathy) or cognitive impairment, defined as a score > 4 on the Six-Item Screener.27

Data Collection

This analysis used data collected in the HEART-IN-DYADS study at baseline: the SC-CHDI v3.0, a sociodemographic survey, the Charlson Comorbidity Index,28 and the Self-Care Self-Efficacy Scale.7 The Self-Care Self-Efficacy Scale is a 10-item self-report measure of self-care self-efficacy in chronic illness.7 Also on the basis of the theory of self-care in chronic illness,14 the Self-Care Self-Efficacy Scale measures self-efficacy in self-care maintenance, monitoring, and management and replaces the previous condition-specific self-care confidence scale. Scores on a 5-point Likert scale are summed and standardized to 100; higher scores indicate higher self-efficacy.

The Italian version of the 23-item SC-CHDI v3.0 underwent a process of translation and back-translation before its use. Two Italian nurse researchers who were fluent in English and had expertise in self-care translated the English version into Italian; afterward, a bilingual English-Italian teacher back-translated the SC-CHDI v3.0 into English. This version was checked by the instrument developers and approved.

After receiving institutional review board approval, research assistants trained in the parent study protocol, explained the study, obtained informed consent, and collected data during face-to-face interviews. Data were then verified for accuracy and manually entered into REDCap Web-based software.29

Sample Size

A sample size of 200 participants was needed to allow adequate inference in explorative or confirmatory analysis.30 A sample of 10 individuals per each item composing a scale is recommended to test dimensionality and internal consistency.31 As noted previously, the SC-CHDI was not intended as an overall self-care measure; it was designed as an inventory with 3 separate scales measuring 3 different constructs. The Self-Care Maintenance Scale was the longest scale with 9 items. Thus, a sample of 90 patients would have been adequate to address the main study objective (ie, dimensionality and internal consistency). The sample size was increased to 205 participants to represent different clinical and social conditions, levels of education, and ages.

Statistical Analysis

Analysis was performed in 4 phases. First, we described the sample using means, standard deviations, percentages and frequencies, and skewness and kurtosis coefficients, where appropriate. Missing data were assessed at the variable and item level, but no missing data were found.

Second, we tested the internal validity of the SC-CHDI v3.0. Because the instrument is theory based, we used a CFA approach to identify the number of dimensions in each scale. Consistent with previous validation studies conducted with other self-care instruments32–34 based on the theory of self-care of chronic illness, 4 separate CFAs were tested: one for each SC-CHDI v3.0 scale (self-care maintenance, self-care monitoring, and self-care management) and one (simultaneous CFA) considering all items of the instrument.

The following goodness-of-fit indices were considered to evaluate the appropriateness of CFA model solution35: omnibus fit indices such as χ2, the comparative fit index (CFI; values > 0.95 indicate good fit), the Tucker-Lewis Index (TLI; values > 0.90 indicate a good fit), the root mean square error of approximation (RMSEA; values < 0.06 indicate good fit),36 and the standardized root mean square residual (SRMR; values ≤ 0.06 indicate good fit). Because of the slightly skewed distribution, the maximum likelihood robust method for parameter estimation was used in the CFA.37 We considered factor loadings as adequate if greater than |0.30|.38

Third, we tested internal consistency reliability of the SC-CHDI v3.0. Cronbach α coefficient was computed for the unidimensional scale. For multidimensional scales (ie, when more than 1 latent factor explains the correlations among the items), we used the global reliability index39 and the factor score determinacy coefficient.40,41 The global reliability index considers related factor loadings and the covariances between residuals, whereas the factor score determinacy coefficient represents the correlation between the true factor score and the estimated factor score; thus, it describes how well the factor is measured.42 All these indices are considered adequate if above 0.70.

Fourth, we assessed construct validity by testing this theoretical hypothesis: if the SC-CHDI v3.0 measures the concepts described in the theoretical framework, then self-care self-efficacy will be significantly associated with self-care maintenance, monitoring, and management as we have shown in previous research.43,44 This hypothesis was posed based on previous research demonstrating the strong influence of self-efficacy in promoting self-care.

Analyses of validity and reliability were performed using MPLUS 8.545 and SPSS 25,46 respectively.

Results

Sample Description

Table 1 summarizes the characteristics of participants. Briefly, the sample (n = 205) was predominantly male (79%), married (62%), and retired (54%), with a mean age of 65.3 ± 11.1 years. More than half (52%) had at least a high school education; 41% reported making ends meet financially with some degree of difficulty. The sample had few comorbid conditions.

Table 2 reports the descriptive analysis of the SC-CHDI v3.0 items. Regarding the self-care maintenance scale, the item with the highest score was item 1 (Keep appointments with your health-care provider), M = 4.1 ± 1.4. The lowest score was on item 3 (Do something to relieve stress), M = 2.3 ± 1.4.

TABLE 2 - Items' Description of the Self-Care of Coronary Heart Disease Inventory v3.0
Mean (±SD) Skewness Kurtosis
Self-Care Maintenance Scale
Listed below are common instructions given to persons with heart disease. How routinely do you do the following?
 Illness-related behaviors (3 items)
  1. Keep appointments with your healthcare provider? 4.09 (1.37) −1.28 0.19
  2. Take aspirin or other blood thinner? 3.27 (1.80) −0.28 −1.75
  5. Take prescribed medicines without missing a dose? 4.01 (1.34) −1.21 0.20
 Health-promoting behaviors (6 items)
  8. Eat fruits and vegetables? 4.02 (1.17) −1.09 0.37
  6. Ask for low fat items when eating out or visiting others? 2.57 (1.43) 0.30 −1.22
  4. Do physical activity (eg, take a brisk walk, use the stairs)? 2.61 (1.50) 0.34 −1.30
  3. Do something to relieve stress (eg, medication, yoga, music)? 2.31 (1.41) 0.59 −1.06
  9. Avoid cigarettes and/or smokers? 3.24 (1.81) −0.25 −1.77
  7. Try to avoid getting sick (eg, flu shot, wash your hands)? 3.92 (1.37) −1.01 −0.31
 Total scale score 58.5 (19.7) −0.28 −0.31
Self-Care Monitoring Scale
Listed below are common things that people with coronary heart disease monitor. How often do you do the following?
 10. Monitor your condition? 2.90 (1.48) 0.06 −1.33
 11. Pay attention to changes in how you feel? 3.18 (1.40) −0.22 −1.16
 12. Check your blood pressure? 3.04 (1.42) −0.05 −1.16
 13. Monitor whether you tire more than usual doing normal activities? 2.98 (1.42) −0.05 −1.27
 14. Monitor for medication side effects? 2.41 (1.46) 0.56 −1.11
 15. Monitor for symptoms? 3.08 (2.50) −0.61 −1.34
 16. Monitor your weight? 2.97 (1.4) −0.02 −1.04
 Total scale score 49.1 (25.5) −0.02 −0.72
Many people with heart disease have symptoms of chest pain, chest pressure, burning, heaviness, shortness of breath, and fatigue. The last time you had a symptom…
 17. How quickly did you recognize it as a heart symptom? 3.18 (1.5) −0.21 −1.40
Self-Care Management Scale
Listed below are actions that people with heart disease use. If you have a symptom, how likely are you to try one of these actions?
 Consulting behaviors (2 items)
  21. Call your healthcare provider for guidance 4.10 (1.3) −1.38 −1.45
  22. Tell your healthcare provider about the symptom at the next office visit 4.31 (1.1) −1.25 0.33
 Problem-solving behaviors (4 items)
  18. Change your activity level (slow down, rest) 3.79 (1.3) −0.12 −1.47
  19. Take an aspirin 3.22 (1.6) −0.59 −0.73
  20. Take a medicine to make the symptom decrease or go away 3.17 (1.6) −0.18 −1.60
Think of a treatment you used the last time you had a symptom of heart disease. −1.60 1.71
 23. Did the treatment you used make you feel better? 3.24 (1.4) −0.19 −1.27
 Total scale score 64.59 (21.63) −0.32 −0.41

In the self-care monitoring scale, the item with the highest score was item 11 (Pay attention to changes in how you feel), M = 3.2 ± 1.4, whereas the item with the lowest score was item 14 (Monitor for medication side-effects), M = 2.4 ± 1.5.

In the self-care management scale, the item with the highest score was item 22 (Tell your healthcare provider about the symptoms at the next office visit), M = 4.3 ± 1.1, whereas the item with the lowest score was item 20 (Take a medicine to make the symptoms decrease or go away), M = 3.2 ± 1.55.

Testing the Internal Validity of the SC-CHDI v3.0

Self-Care Maintenance Scale

Self-care maintenance was described as encompassing “illness related behaviors” (items 1, 2, and 5) and “health promoting behaviors” (items 3, 4, and 6–9). Thus, we specified a 2-factor confirmatory model with consulting and autonomous dimensions. The goodness-of-fit indices of this model were adequate: χ2(26, N = 205) = 40.64, P = .03, CFI = 0.93, TLI = 0.90, RMSEA = 0.05 (90% CI, 0.015–0.08), P = .42, and SRMR = 0.05. Inspection of the modification indices revealed an excessive covariance between items 4 (Do physical activity) and 3 (Do something to relieve stress). Because physical activity is one of the practices used to manage stress, we had theoretical justification for a post hoc error covariance between these 2 items. When we reran the model specifying this residual covariance, the model had excellent fit: χ2(25, N = 205) = 31.86, P = .16, CFI = 0.97, TLI = 0.95, RMSEA = 0.04 (90% CI, 0.00–0.07), P = .705, and SRMR = 0.045. All factor loadings were significant and adequate, except for item 4 (Do physical activity), which loaded at 0.22. The 2 dimensions were positively and significantly correlated at 0.615 (P < .001) (Figure 1).

F1
FIGURE 1:
Confirmatory factor analysis of the self-care maintenance scale (n = 205). Rectangles represent observed variables; circles represent latent factors. Numbers near the 1-headed arrows are factor loading coefficients; numbers close to the 2-headed arrows are correlation coefficients. Loadings come from Mplus completely standardized solutions and are all statistically significant.

Self-Care Monitoring Scale

We posited that a single factor would underlie the 7 items of this scale, so we specified a single-factor model CFA. The goodness-of-fit indices of this model were good: χ2(14, N = 205) = 29.832, P = .008, CFI = 0.96, TLI = 0.95, RMSEA = 0.07 (90% CI, 0.037–0.111), P = .13, and SRMR = 0.04.

Modification indices demonstrated high, significant indices associated with the covariances between residuals of items 10 (Monitor your condition), 11 (Pay attention to changes in how you feel), and 12 (Check your blood pressure). These associations can be explained by the fact that items 10 and 11 both address observing and detecting changes in signs and symptoms (eg, body listening).6 The second pair of items (10 and 12) ask about general and specific self-care monitoring behaviors. Thus, we specified a model that included these residual covariances. The fit indices of this model were strong: χ2(12, N = 205) = 11.56, P = .482, CFI = 1.00, TLI = 1.00, RMSEA < 0.001 (90% CI, 0.00–0.07), P = .86, and SRMR = 0.02. All factor loadings were significant and adequate (Figure 2).

F2
FIGURE 2:
Confirmatory factor analysis of the self-care monitoring scale (n = 205). Rectangles represent observed variables; circles represent latent factors. Numbers near the 1-headed arrows are factor loading coefficients. Loadings come from Mplus completely standardized solutions and are all statistically significant.

Self-Care Management Scale

Self-care management is defined by the 2 dimensions of autonomous and consulting behaviors, with each dimension measured by 4 and 2 items, respectively. Thus, a 2-factor confirmatory model was specified that yielded a fit that was partially adequate: χ2(8, N = 205) = 22.83, P = .004, CFI = 0.93, TLI = 0.87, RMSEA = 0.095 (90% CI, 0.05–0.14), P = .048, and SRMR = 0.07. Inspection of the modification indices revealed that the cause of the misfit resided in the excessive error covariance between items 20 (Take a medicine to make the symptom decrease or go away) and 21 (Call your healthcare provider for guidance). Both of these items refer to often complementary and/or consequential behaviors (Talking to a healthcare provider for guidance/before taking a drug to manage symptoms) for managing signs and symptoms of CHD.

When we respecified the model including the residual covariance between items 20 and 21, the model yielded a strong fit: χ2(7, N = 205) = 6.57, P = .47, CFI = 1.00, TLI = 1.00, RMSEA ≤ 0.001 (90% CI, 0.00–0.08), P = .76, and SRMR = 0.02. All factor loadings were significant and adequate, except for item 23 (Did the treatment you used make you feel better), which had a loading of 0.27. The 2 dimensions were positively and significantly correlated at 0.68 (<0.001) (Figure 3).

F3
FIGURE 3:
Confirmatory factor analysis of the self-care management scale (n = 205). Rectangles represent observed variables; circles represent latent factors. Numbers near the 1-headed arrows are factor loading coefficients; numbers close to the 2-headed arrows are correlation coefficients. Loadings come from Mplus completely standardized solutions and are all statistically significant.

Simultaneous Confirmatory Factor Analysis

To demonstrate that the factors underlying the SC-CHDI v3.0 scales emerged clearly, we performed a simultaneous CFA on the combination of items. This analysis supported a more general model with the following indices: χ2(195, N = 205) = 275.783, P = < 0.001, CFI = 0.933, TLI = 0.921, RMSEA = 0.045 (90% CI, 0.03–0.06), P = .76, and SRMR = 0.06. Factor loadings ranged from 0.254 (item 23, Did the treatment you used make you feel better?) to 0.87 (item 22, Tell your healthcare provider about the symptom at the next office visit).

Testing Internal Consistency Reliability

Because the self-care maintenance scale has 2 dimensions, we used a multidimensional coefficient—the global reliability index for multidimensional scales to test internal consistency reliability. This coefficient was adequate at 0.94. The factor determinacy score was 0.85 for the consulting behaviors dimension and 0.82 for the autonomous behaviors dimension. Because the self-care monitoring scale has 1 dimension, we computed Cronbach α, which was adequate at 0.83. The factor determinacy score was also satisfactory at 0.94. Because the self-care management scale has 2 dimensions, we computed the global reliability index for multidimensional scales, which was 0.87. Factor determinacy scores were 0.91 for the consulting behaviors dimension and 0.84 for the autonomous behaviors dimension.

Testing Construct Validity

The Pearson correlation coefficient were computed to examine the relationship between the Self-Care Self-Efficacy Scale scores and the SC-CHDI v3.0 self-care maintenance, monitoring, and management scores. These correlations were r = 0.28 (P = .01), r = 0.30 (P = .01), and r = 0.52 (P = .01), respectively.

Discussion

The purpose of this study was to test the psychometric properties of the revised SC-CHDI v3.0, which is composed of 3 scales: self-care maintenance, monitoring, and management. The results of this study provide evidence that the SC-CHDI v3.0 has adequate reliability and construct validity.

Our findings support the conceptual basis of self-care of chronic illness in persons with CHD as a process of self-care maintenance, monitoring, and management. We identified 2 dimensions of self-care maintenance, which we labeled as autonomous and consulting behaviors, consistent with the previous version of the instrument.8,47 The new self-care maintenance item, “try to avoid illness (eg, get a flu shot, wash hands),” fit with the autonomous behavior dimension, whereas in our recent analysis of the Self-Care of Hypertension Inventory v3.0, the results loaded equally on both the dimensions.47 Loading on the autonomous behavior dimension is consistent with global public health messages that have stressed the importance of autonomous actions such vaccinations, masks, and social distancing during the COVID-19 pandemic. In Italy, a study found that cardiovascular conditions and diabetes were common in patients who died from COVID-19 infection.48 The data used in this analysis were collected during the pandemic; our results may reflect the heightened awareness of these health-promoting behaviors.

The SC-CHDI is one of a family of self-care instruments, all of which are theoretically based. In factor analysis of the various instruments, slightly different factor structures have been evident. For example, the self-care maintenance scale of the SC-CHDI v3.0 has a 2-factor structure, but a 4-factor structure was identified in the self-care maintenance scales of the Self-Care of Chronic Obstructive Disease Inventory and the Self-Care of Diabetes Inventory.34,49 Although the factor structures differ subtly across these instruments, conceptually the behaviors are aligned as they reflect behaviors that are autonomous or influenced by others. For example, in the Self-Care of Chronic Obstructive Disease Inventory,34 the self-care maintenance scale has 4 factors called disease prevention, treatment adherence, improving breathing behaviors, and physical activities. The behaviors in the disease prevention and treatment adherence factors are similar to the SC-CHDI consulting behaviors as they are directed or influenced by others. Similarly, the improving breathing behaviors and physical activities reflect health promotion behaviors that are autonomous. The similar factor structure in the Self-Care of Heart Failure Index, Self-Care of Hypertension Inventory, and SC-CHDI likely reflects the same essential behaviors across cardiovascular disease conditions.

The SC-CHDI v3.0 self-care management scale had 2 dimensions, labeled as autonomous and consulting. Three autonomous behaviors included those actions a patient might take on their own (eg, change activity) while the consulting behaviors are linked to the healthcare provider. This analysis revealed a different factor structure than the 2 factors we found in SC-CHDI v2 (early recognition and response and delayed response); the key difference was in the dimension of time. The previous structure included monitoring and symptom recognition items that factored into early versus delayed symptom management response, but these items are no longer in this scale. The SCHDI v3.0 autonomous dimension is similar to the autonomous behavior dimension seen in other scales.41,47

The new SC-CHDI self-care monitoring scale assessing the practice of routine surveillance6 was unidimensional. The 7 items on this scale included objective actions (eg, check your blood pressure) as well as subjective actions used to monitor one's condition (eg, pay attention to changes in how you feel). Such routine monitoring may increase awareness of health status changes and influence engagement in self-care maintenance behaviors (eg, medication and/or diet adherence). In addition, recognition of health changes informs self-care management. Collectively, these behaviors support our previous work that people develop individualized tactics to listen to bodily cues.6

The strong psychometric properties of the 3 SC-CHDI v3.0 scales support its use in research to elucidate how persons with CHD maintain health and monitor, recognize, and label their signs and symptoms as well as how they respond to those changes. Descriptive data using the SC-CHDI v3 can inform the development of interventions focused on secondary prevention of CHD.

There are several limitations to this study. First, this analysis was limited to 1 population with CHD, which was recruited from 1 European country. The sample was predominately male (79%) and lacked diversity in race and ethnicity. The sample was also relatively young (mean age, 65 years) and medically stable with few comorbid conditions. Further testing in a more diverse population that includes an adequate sample of women is needed. We also recommend future testing of the instrument that includes test-retest analysis and item response theory to provide a more comprehensive analysis of item and scale performance.

Conclusions

The revised SC-CHDI v3.0 provides a useful and sound measure of the essential components of self-care. The inclusion of the new self-care monitoring scale is an important dimension of this revision. As such, the updated SC-CHDI v3.0 addresses an important gap in self-care research across global populations.

What’s New and Important

  • The updated SC-CHDI v3.0 reflects the theory of self-care of chronic illness and the theoretical concepts of self-care maintenance, monitoring, and management.
  • The strong psychometric properties of the 3 SC-CHDI v3.0 scales support its use in research to elucidate how persons with CHD maintain health and monitor, recognize, and label their signs and symptoms as well as how they respond to those changes.

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Keywords:

coronary heart disease; psychometric testing; self-care

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