Bandura's exercise self-efficacy scale: Validation in an Australian cardiac rehabilitation setting

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Abstract

Background

Despite the established benefits of cardiac rehabilitation (CR) in improving health outcomes for people with cardiovascular disease, adherence to regular physical activity at recommended levels remains suboptimal. Self-efficacy has been shown to be an important mediator of health behaviour, including exercise.

Objectives

To assess the psychometric properties of Bandura's exercise self-efficacy (ESE) scale in an Australian CR setting.

Design

Validation study.

Setting

Cardiac rehabilitation.

Participants

One hundred and ten patients (Mean: 60.11, S.D.: 10.57 years).

Methods

Participants completed a six-minute walk test (6MWT) and Bandura's exercise self-efficacy scale at enrolment and on completion of a 6-week CR program.

Results

Bandura's ESE scale had a single factor structure with high internal consistency (0.95), and demonstrated no floor or ceiling effects. A comparison of ESE scores by distance walked on 6MWT indicated those who recorded more than 500 m at baseline had significantly higher ESE scores (Mean: 116.26, S.D.: 32.02 m) than those patients who only achieved up to 400 m on the 6MWT at baseline (Mean: 89.94, S.D.: 29.47 m) (p = 0.044). A positive and significant correlation between the change in scores on the ESE scale and the change in the 6MWT distance (r = 0.28, p = 0.035) was seen.

Conclusions

The ESE scale was a robust measure of exercise self-efficacy over the range of patients attending this outpatient cardiac rehabilitation program. Interventions to improve self-efficacy may increase CR patient's efficacy for regular physical activity.

Introduction

Coronary heart disease (CHD), the most common manifestation of cardiovascular disease (CVD), is the leading cause of death both globally (Mathers and Loncar, 2006), and nationally, accounting for 19.5% of all deaths in Australia in 2002, including 10.7% directly from acute myocardial infarction (AMI) (National Heart Foundation of Australia, 2005). Considered a disease of lifestyle, the clinical course of CHD can be favourably altered with interventions for lifestyle changes and modification of risk factors (Giannuzzi et al., 2003). Cardiac rehabilitation (CR) is an internationally endorsed model of secondary prevention which has been shown to be an effective approach to achieve these changes (Jolliffe et al., 2001, Taylor et al., 2004).

Australia supports a system of universal health care coverage and endorses CR as part of a national policy framework, with these programs predominantly coordinated by nurses (National Heart Foundation of Australia and Australian Cardiac Rehabilitation Association, 2004). Although the benefits of CR programs in reducing both cardiac and all-cause mortality are well established (Jolliffe et al., 2001, Taylor et al., 2004, Williams et al., 2006), maintaining regular physical activity at recommended levels remains problematic (Arrigo et al., 2008, Blanchard et al., 2007, Zhao et al., 2008). Efficacy expectation, more commonly known as self-efficacy, is the judgement of one's capacity to perform a specific action (Bandura, 1997), and has been found to be an important determinant of adherence to health behaviour change, including physical activity in the CR setting (Luszczynska and Sutton, 2006, Meland et al., 1999, Woodgate and Brawley, 2008). Self-efficacy influences the level of perseverance, commitment and effort exerted to goal achievement (Schwarzer, 1992).

In operationalising the concept of self-efficacy, the most important consideration is that scales must be tailored to the particular domain of functioning that is of interest, and be context-specific (Schwarzer, 1992). In addition, they must assess the multifaceted ways in which efficacy beliefs operate within the selected activity domain (Bandura, 2006). Bandura's exercise self-efficacy scale (Bandura, 2006) has been validated in a Korean sample with chronic disease, with a single factor found to explain 77.5% of the variance (Shin et al., 2001). It has also been shown to be a useful measure of exercise beliefs (Shin et al., 2001), and an influential variable on commitment to a plan for exercise (Shin et al., 2006), making it a potentially useful measure in exercise-based CR programs. However, first it will need to be validated for use in an Australian sample in a CR setting. Therefore, the purpose of this study was to assess the psychometric properties of Bandura's exercise self-efficacy (ESE) scale in a cardiac rehabilitation setting in: (a) the distribution of scores including the presence of floor and ceiling effects; (b) construct validity; (c) internal consistency; and (d) the responsiveness to detect change over the 6-week period of the CR program.

Section snippets

Design and setting

This validation study assessed the psychometric properties of Bandura's exercise self-efficacy scale which is being used in a larger study assessing risk factor modification in CR attendees. Participants were recruited from three nurse-led, Phase II CR services in the western Sydney region of New South Wales, Australia. In this health service, medical in-patients may commence their CR program pre-discharge (as early as Day 3 post-event), while cardiothoracic patients can commence 21 days

Sample description

The sample of 110 patients comprised of 79 males and 31 females, with a mean age of 60.11 (S.D.: 10.57) years. Of the sample, 89 participants completed 6-week follow-up. Baseline clinical and demographic characteristics are presented in Table 1.

Floor and ceiling effects

The mean score of the ESE scale in this CR population was 103.64 (S.D.: 34.69), with a median of 103.50 and a well-shaped normal distribution with skewness of 0.25 and kurtosis of 0.01. The Kolmogorov-Smirnov test for normality showed normal distribution

Discussion

Based on the results of this psychometric evaluation, the ESE scale was a robust measure of self-efficacy for regular exercise over a range of patients attending outpatient CR. Importantly, the score distributions of the ESE scale in this study showed the sensitivity of this instrument in a CR population. One factor explained 58% of the variance in scores, consistent with the single-factor structure reported by Shin et al. (2001).

While the absence of any ceiling effects suggest the items

Conclusion

The exercise self-efficacy scale used in this study is a reliable and valid measure, and appropriate for use in a CR population. Further testing of this scale with other populations with chronic illness will be needed in assessing not only external validity for different populations, but also the predictive utility of the scale to assess the capacity to initiate and sustain regular physical activity once patients have left the ‘therapeutic microenvironment’ of CR. Use of this scale in future

Acknowledgements

We wish to thank Dr Albert Bandura for permission to modify his exercise self-efficacy scale. Permission granted March 3 2006. We also wish to thank staff from the Sydney West Area Health Service Cardiac Education & Assessment Programs (CEAP), and the patients who participated in this study.

Contributors. PD contributed to the study design. PD, BE and YS were involved in data collection and analysis and in the preparation of manuscript.
Conflict of interest

None declared.
Funding

This study was

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