Using a theoretical approach to identify factors influencing adherence to an exercise programme for adults with venous leg ulcers

Abstract

This study assessed the relationships between self-efficacy, outcome expectations, fear-avoidance beliefs and adherence to an exercise for a home-based exercise programme for adults with venous leg ulcers. Patients (n=63) were randomised to receive either an intervention or usual care group. Of those in the exercise intervention group, 59per cent adhered to the exercise protocol more than 75per cent of the time. There was a significant relationship between self-efficacy and outcome expectations, and both of these constructs were significantly related to adherence to the leg exercise programme. Adherence significantly correlated with wound healing indicating a possible pathway to healing.

Keywords

adherence behavioural medicine exercise social cognitive theory venous leg ulcers

Introduction

Systematic reviews have shown that the cornerstone treatment of venous leg ulcers (VLUs) is the application of compression therapy to reduce venous hypertension (Cullum et al., 2012; O’Meara et al., 2012; Van Hecke et al., 2008). VLUs account for approximately 70 per cent of all chronic leg ulcers (Abbade and Lastoria, 2005) and are the result of chronic venous insufficiency or venous disease in the lower leg. Up to 15–30 per cent of chronic VLUs do not respond to compression treatment (O’Meara et al., 2009) and remain unhealed, even after a year of treatment (Kurd et al., 2009), suggesting alternative adjunct treatments are necessary.

A growing body of literature provides evidence for the beneficial effects of exercise. Exercise may be of particular benefit to patients with VLUs because it promotes venous return (Sochart and Hardinge, 1999) which is crucial in reducing venous hypertension. Despite evidence to suggest that exercise improves calf muscle function in this patient population (Heinen et al., 2012; Jull et al., 2009; Kan and Delis, 2001; Padberg et al., 2004; Yang et al., 1999), an exercise programme is only effective if adhered to. Currently, there is little research studying the mechanisms of exercise adherence in this patient population.

Chronic disease now contributes to over 70 per cent of the disease burden in Australia, a figure that is expected to increase to 80 per cent by 2020 (Jordan and Osborne, 2007). Therefore, the focus on self-management is not surprising given the burden of chronic disease in Australia and the shift in health policy towards patient-centred care (Cameron-Tucker et al., 2014; Lorig et al., 2013). Evidence suggests that patients with effective self-management skills make better use of healthcare professionals’ time and have enhanced self-care (Barlow et al., 2000; Kennedy et al., 2013; Lorig et al., 1999). However, self-management skills often require behaviour change.

Social cognitive theory (SCT) provided the theoretical framework for this study. This theory proposes that a group of core determinants influence the successful performance of health-promoting behaviours such as self-care activities (e.g. exercise) for chronic disease management (Bandura, 2004). The constructs of the SCT model are self-efficacy, outcome expectations, goals and sociocultural factors (barriers and facilitators). Self-efficacy is defined as people’s beliefs about their capabilities. Individuals with higher levels of self-efficacy regard tasks as a challenge rather than a risk, setting higher goals for themselves and are more likely to believe that they are capable of overcoming difficulties and barriers. People with low self-efficacy avoid difficult tasks; they have low aspirations and a weak commitment to their goals (Bandura, 1997). Goals are powerful motivators and are important for focusing and directing activity.

SCT is one of the most comprehensive theories used to explain human behaviour and has been used for the development and successful implementation of smoking cessation programmes and physical activity interventions (Di Loreto et al., 2003; Tudor-Locke et al., 2001). Studies exploring other chronic diseases have found significant relationships between performance of self-management activities and psychosocial factors such as depression (Maeda et al., 2013) and social support (Jeon and Kim, 2006). In recent years, there have been some studies investigating the influence of self-efficacy, outcome expectations, fear-avoidance beliefs (O’Brien et al., 2014a; Roaldsen et al., 2011) and self-care practices for patients with VLUs (Brown, 2010, 2014; Van Hecke et al., 2011). This reflects an emerging interest in the relationship between psychological constructs such as self-efficacy for patients with VLUs, and whether people with VLUs could be supported by self-management programmes based on similar concepts. Thus, it is important to determine comprehensively how the SCT constructs operate together in the context of changing exercise-related behaviour in VLU patients; as all of the constructs are potentially modifiable and could be targeted and manipulated to enhance exercise in this population. This study investigated aspects of some of these core determinants: self-efficacy, outcome expectations, selected psychosocial factors that influence self-efficacy, and selected social and structural facilitators or impediments to maintaining exercise. This study was part of a larger investigation to identify factors associated with healing that found adherence to a calf muscle exercise programme to be significantly associated with healing.

Methods

Aim

To determine which demographic or psychosocial factors influenced adherence to an exercise programme to improve the healing rates for adults with VLUs.

Design

A randomised controlled trial (RCT) was undertaken to determine the effectiveness of a home-based progressive resistance exercise programme in comparison to usual care on the effects on healing rates, functional ability and health-related quality of life for VLU patients.

Patients were randomised after signed informed consent was obtained, according to a predetermined computer-generated randomisation scheme, into one of two groups: a control (usual care) or intervention (exercise) group.

A team of wound care nurses at the respective clinics were trained in the protocol compression techniques for consistency.

Sample

Patients were recruited from two outpatient wound services in Queensland and a community nursing service in Victoria, Australia; all details are provided in another published paper (O’Brien et al., 2017). All patients at the clinics were screened for inclusion in the study. The case definition for venous ulceration was as follows: any break in the skin on the lower leg, no other causative aetiology being present, appearing clinically venous and having an ankle brachial pressure index (ABPI) ≽0.8 ≼ 1.2. Patients were included if they were aged 18 years or older, were able to give informed consent and met the case definition. Patients were excluded if there was cognitive impairment (clinician determined), ulcers of non-venous aetiology and/or unable to understand English.

Data collection and measures

Data on demographic characteristics, medical and venous history and previous leg ulcers were collected from medical records. The wound healing outcome measure was the incidence of complete wound closure at the completion of the study (12 weeks after initiation of exercise intervention). A self-report questionnaire contained the following instruments to measure Self-Efficacy for Exercise (SEE), Outcome Expectations for Exercise (OEE), depressive symptoms, health-related quality of life and social support. The SEE Scale (Resnick and Jenkins, 2000) is a nine-item scaled instrument asking participants about their confidence in performing exercise in a number of different circumstances. To score the scale, the individual scores for each item range from 0 to 10, where 0 represents not confident and 10 represents very confident. The SEE is scored by summing the ratings and dividing by the number of ratings responded to. Higher scores indicate higher SEE. Prior use of this measure with White older adults provided evidence of internal consistency (Resnick and Jenkins, 2000). The OEE Scale (Resnick et al., 2004) is a nine-item scaled instrument about the physical and mental health outcomes of exercise. Participants are asked to agree or disagree with the statement (strongly agree, agree, neither agree nor disagree, disagree or strongly disagree). Like the SEE, the OEE is scored by summing the ratings and dividing by the number of ratings to which one has responded. Similarly, to the SEE, prior use of the OEE with White older adults provided evidence of internal consistency and evidence for validity based on construct validity using hypothesis testing and confirmatory factor analysis (Resnick, 2001). The Fear-Avoidance Beliefs Questionnaire (FABQ) (Waddell et al., 1993) was used to assess fear-avoidance beliefs. The FABQ is a 16-item self-report questionnaire aimed at quantifying the beliefs of how work and physical activity affect pain and whether they should be avoided. The two subscales, fear-avoidance beliefs for work (FABQ–work) and fear-avoidance beliefs for physical activity (FABQ–physical), are scored on a Likert scale of 0–6, from ‘strongly disagree’ to ‘strongly agree’, where higher sum scores indicate stronger fear-avoidance beliefs. Due to the generally older age group, it was expected only a few patients would be working, and therefore, only the FABQ–physical was used. This scale has been used previously in VLU patient populations (Roaldsen et al., 2009). The Medical Outcomes Study Social Support Survey (Sherbourne and Stewart, 1991), a 20-item survey examining the perceived social support available to patients, represents the multiple dimensions of support including emotional/informational, tangible, affectionate and positive social interaction (Sherbourne and Stewart, 1991). The instrument uses self-reported five-point answer scales and subscale totals which are calculated with high scores indicating more support (McDowell and Newell, 1996). Good evidence exists for its reliability and validity (McDowell and Newell, 1996). Finally, the Geriatric Depression Scale (GDS) score is a seven-item version of the GDS 15. The GDS is widely used to screen and assess depression in the older population and has shown good-to-excellent criterion validity as a screening instrument for major depressive disorder (Almeida and Almeida, 1999; Watson et al., 2009).

Exercise adherence data were obtained from data sheets recorded on paper during phone calls, conducted over a 12-week period. Adherence in this study refers to maintaining an exercise regimen for a prolonged period of time. Adherence is voluntary, self-regulated and largely a psychological issue. In this study, adherence to leg exercises was defined as undertaking the recommended exercise intervention for greater than or equal to 75 per cent of the time in order to comply with protocol. This figure has been regularly used in studies defining adherence or compliance to an exercise programme such as exercise programmes addressing chronic back pain (Hicks et al., 2012) and older adults (Van Het Reve et al., 2014). All participants received phone calls to measure self-reported exercise at weeks 2, 4, 6, 8 and 12. A Likert scale was used which asked the participants how often they were performing leg exercises and/or walking; response categories were 0 = not at all, 1 = some or a little of the time and 2 = most or all of the time. The same scale was used for both the leg exercises and walking measure. Therefore, the maximum score a participant could record across the five data collection points was 10.

An important factor in promoting physical activity is exercise adherence. Exercise adherence can be defined as the degree to which a person completes a given exercise prescription (Pinto et al., 2009). Participants have often been defined as adherent if completing 75 per cent of the sessions (Taylor et al., 2011). Therefore, adherence in this study was defined as completing either the leg or walking exercises 75 per cent of the time, determined as any score greater than or equal to 7.5 out of 10. Adherence is often poorly defined in exercise studies.

Intervention

Patients in the intervention group participated in a home-based exercise programme facilitated by a telephone management component for adults with VLUs. The intervention was informed by SCT (Bandura, 2004). To increase self-efficacy, strategies to improve goal achievement were embedded throughout the intervention. The intervention was based on the SMART (Specific, Measurable, Achievable, Realistic and Timely) concept, therefore assisting individuals to improve their exercise self-efficacy. People perform better when they are committed to achieving certain goals. Through an understanding of the effect of goal setting on individual performance, health professionals are able to use goal setting to benefit participants. Three moderators indicate goal setting success: (1) the importance of the expected outcomes of goal attainment, (2) self-efficacy – one’s belief that they are able to achieve the goals and (3) commitment to others – promises or engagements to others can strongly improve commitment (Taylor et al., 2011). This goal setting theory complements SCT that purports that an individual’s learning is directly related to what an individual observes and subsequently learns by imitating the actions of another while being influenced by their own thoughts and the environment in which they are learning. The health education component of this study was designed to increase SEE, exercise adherence and OEE of other VLU-related symptoms. The exercise coaching sessions addressed the following: the use of exercise to manage symptoms and improve healing opportunities, basic elements of a balanced exercise programme; how to exercise; barriers to exercise maintenance, identifying social support and strategies to overcome barriers. Detailed information on the intervention protocol has been previously published (O’Brien et al., 2014b).

Usual care group

The patients assigned to the usual care group received phone calls at the same time points as the intervention group; however, they were not provided with any goal setting strategies. If at any point a participant in the usual care group asked for exercise advice, they were referred to the wound care nurses in the clinic to discuss standard advice.

Data analysis

Quantitative data were analysed with SPSS v21 (SPSS Inc., Chicago, IL, USA). Descriptive statistics were undertaken for all variables, followed by correlations, chi-squares, t-tests and Mann–Whitney U tests as appropriate to examine bivariate relationships between adherence to an exercise programme and demographic, health and psychosocial variables. All the participating patients gave their written informed consent. The protocol was approved by the Human Research Ethics Committee at each participating centre and complied with the Helsinki Declaration ethical rules for human experimentation. Patients’ freedom to withdraw consent at any time was offered.

Results

A total of 340 participants were identified between the three clinical sites between June 2012 and March 2014. In all, 62 patients with venous leg ulceration, 32 males (51.6%) and 30 females (48.4%) aged between 31 and 97 years (71.5 ± 14.6 years) met all the inclusion criteria and were randomised per protocol to an intervention or usual care group for the duration of the study.

A total of 12 per cent of participants were noted to be at risk of depression with a GDS score of depressive symptoms. In all, 23 (37.1%) participants were currently employed or self-funded retirees, while 38 (61.3%) received the aged or disability pension with 63 per cent of participants having access to a healthcare card and 44 per cent of participants lived alone. Only four participants (6.5%) were carers for another person. The baseline characteristics for the psychosocial measures are reported in Table 1.

Table 1.

Baseline characteristics for the psychosocial measures.

	Mean (SD)
GDS^a	1.1 (±1.8)
Self-Efficacy for Exercise^b	4.5 (±1.4)
	Median (range)
Fear-avoidance beliefs^c	9.3 (0–23)
MOS Social Support^d	83 (19–95)
Outcome expectations^e	3.5 (2–5)

SD: standard deviation; GDS: Geriatric Depression Scale; MOS: Medical Outcomes Study.

Geriatric Depression Scale Short Form – range 0–7, where higher scores indicate higher risk of depression.

Self-Efficacy for Exercise – range 1–7 (averaged), where higher scores indicate higher self-efficacy towards exercise.

Fear-avoidance beliefs questionnaire – range 0–24, where higher scores indicate a higher level of fear.

Medical Outcomes Study (MOS) Social Support Index – scale from 0 to 100, where higher scores indicate more support.

Outcome Expectations for Exercise Scale – range 1–5 (averaged), where higher scores indicate higher outcome expectations towards exercise.

Adherence to the exercise programme

Adherence to the leg exercise protocol was self-reported. Participants were asked at subsequent telephone follow-up calls to report if they were performing the recommended leg exercises. It was then recorded if the participants were performing the exercises as follows: (1) none of the time, (2) some of the time or (3) most or all of the time. In order to be classified as adherent participants needed to adhere to the leg exercises prescribed at least 75 per cent of the duration of the intervention. A total of 19 participants (59%) of the intervention cohort were adherent to the leg exercises more than 75 per cent of the time. The main reasons participants shared for not adhering to the leg exercises ranged from health deterioration of their other chronic conditions, pain related to the leg ulcer, boredom or a general dislike for exercise and forgetting to do the exercises.

Six participants in the intervention group said they required more face-to-face support. Only one of the participants was able to reach the final stage of the exercise protocol, that is, level 3 stage 4. Most participants did not regulate or manage their own exercise programme. Seven participants actually increased their levels of sets or repetitions without guidance from the first author (J.O.), and all of these participants scored highly on the SEE and maintained a high level of intensity in relation to reported leg exercise programme.

Demographic, health and psychosocial factors influencing adherence to leg exercises

At the bivariate level of analysis, adherence to the exercise programme was positively associated with a participant having heart disease (Spearman’s ρ = 0.57, p = 0.001), statin use (Spearman’s ρ = 0.51, p = 0.02), higher SEE (Spearman’s ρ = 0.44, p = 0.02) and OEE (Spearman’s ρ = 0.49, p = 0.01). Participants who wore compression >30 mmHg were less likely to adhere to the exercise programme (Spearman’s ρ = −0.46, p = 0.01). If participants experienced any of the following symptoms at baseline – atrophie blanche, lymphoedema and lipodermatosclerosis – these were all negatively associated with adherence to the exercise programme, atrophie blanche (Spearman’s ρ = −0.51, p = 0.004), lymphoedema (Spearman’s ρ = −0.41, p = 0.03) and lipodermatosclerosis (Spearman’s ρ = −0.49, p = 0.01). No significant differences were found according to the GDS score or Medical Outcomes Social Support Survey score.

Based on the theoretical framework, relationships between factors purported to mediate a person to change their behaviour (i.e. self-efficacy and outcome expectations) and their commitment to an exercise programme (adherence) in relation to the healing of the VLU were examined. As shown in Table 2, there was a significant relationship between SEE and OEE. SEE and OEE correlated with adherence to an exercise programme. In addition, there was a significant relationship between adherence to an exercise programme and wound healing.

Table 2.

Correlation between social cognitive constructs, healing and adherence for the entire cohort.

	SEE^a	OEE^b	FAB^c	Adherence^d	Wound healed by 12weeks^e
1. Self-Efficacy for Exercise (SEE)^a		0.55**	–0.24	0.44*	0.14
2. Outcome Expectations for Exercise (OEE)^b	–		–0.44*	0.31*	0.02
3. Fear-avoidance beliefs (FAB)^c	–	–		–0.18	–0.09
4. Adherence to exercise programme (> 75% of the time)^d	–	–	–		0.46**

Self-Efficacy for Exercise – range 1–7 (averaged), where higher scores indicate higher self-efficacy towards exercise.

Outcome Expectations for Exercise Scale – range 1–5 (averaged), where higher scores indicate higher outcome expectations towards exercise.

Fear-avoidance beliefs questionnaire – range 0–24, where higher scores indicate a higher level of fear.

Adherence to exercise programme - range 1 - 3, where higher scores indicate greater adherence ( > 75% of the time).

Wound healed by 12weeks (Yes/No).

Correlation is significant at the 0.05 level (two-tailed).

Correlation is significant at the 0.01 level (two-tailed).

Discussion

This study provides a step towards gaining an understanding of how self-efficacy and outcome expectations, two major psychological constructs that have attracted significant research attention, may contribute to exercise adherence in VLU patients. Adherence to an exercise programme to improve the healing rates of VLUs was generally low with only 59 per cent of those in the intervention group undertaking the recommended exercises. While these findings appear to be lower than our previous study reporting adherence to exercise for adults with VLUs (Heinen et al., 2012; Jull et al., 2009; O’Brien et al., 2013), this study was based on a self-management intervention.

Adherence to the exercise programme

Adherence is not a simple phenomenon particularly in the area of chronic disease self-management. There is controversy in the literature as to how to define adherence to physical activity, which leads to different interpretations of empirical results and inconsistent evaluations of interventions (Chao et al., 2000). This study defined adherence as performing the leg exercises 75 per cent or more of the time. However, a smaller than expected percentage of participants achieved the defined level of adherence.

Demographic, health and psychosocial factors influencing adherence to leg exercises

Results on demographic, health and psychosocial factors influencing adherence to leg exercises suggest self-efficacy, and outcome expectations are significant influences on adhering to recommendations of leg exercises to assist in improving the healing rates of VLUs.

There is little information in the literature on the impact of psychosocial factors on exercise to improve healing rates of VLUs. Depression has been found to be significantly related to adherence to compression therapy in a sample of adults with healed VLU (Finlayson et al., 2010); however, it was not found to be directly related to adherence in this study. There was a significant relationship between the GDS score and SEE, suggesting an indirect relationship to adherence which would require further investigation.

A study by Roaldsen et al. (2009) found that fear-avoidance beliefs were present in 81 per cent of patients with chronic venous insufficiency, and the odds ratio for low physical activity were about three times higher for patients with strong fear-avoidance beliefs. Surprisingly, no significant relationship between fear-avoidance beliefs and adherence was found in this study. However, there was a significant relationship between OEE and fear-avoidance beliefs suggesting an indirect effect. This highlights the importance of addressing fear as a possibly contributing factor to exercise adherence.

This study provides at least initial support for an SCT model of exercise in VLU patients. According to the theoretical framework and a substantial body of literature, self-efficacy and outcome expectations are two determinants of self-management behaviours. This study suggests that SEE and OEE had a direct relationship to adherence to exercise behaviour, which had a direct relationship to wound healing. Several researchers have argued that it is important to not only evaluate the effect of behaviour change but also the targeted determinants, which can provide insight into the dynamics of changing behaviour. Previous studies have demonstrated relationships between self-efficacy related to exercise and exercise adherence (Plotnikoff et al., 2001; Rejeski et al., 2003). Although Bandura theorised that self-efficacy expectations have a greater influence on behaviour than outcome expectations, there are several studies with older adults that suggest outcome expectations independently influence health behaviours (Resnick et al., 2000; Williams et al., 2005; Wojcicki et al., 2009).

Although the present results are promising, several limitations must be acknowledged. First, although this study adopted an RCT design, our time frame of 3 months was somewhat limited. Longer-term longitudinal studies and randomised controlled exercise trials will be needed to determine how the proposed relationship among changes in model constructs hold across longer periods of time and as a result of an intervention. Second, although no restrictions were placed on disease characteristics or time since diagnosis, the sample was relatively homogeneous and may not be entirely representative of this population at large. Thus, it is important to examine whether these models can be replicated in other, more diverse samples of VLU patients (e.g. older and younger, obese and non-obese).

A further limitation of this study was the use of self-report measures of adherence, which may underestimate actual non-adherence rates as patients may respond in ways that are socially desirable. However, questionnaire-based self-report measures are widely used in the literature. Finally, due to lower-than-expected recruitment numbers, structural equation modelling was unable to be used. With larger sample sizes, this approach may prove to be a more robust method of measuring relationships between the constructs of SCT and exercise adherence.

Despite these limitations, this study provides important evidence that outcome expectations and self-efficacy have strong contributions to treatment adherence behaviour in adults with VLUs and that outcome expectations may serve as a key mechanism for these relationships. It has been suggested that health professionals are not able to predict patients’ adherence at above chance level (Kravitz et al., 1993) and self-efficacy, therefore, may serve as a proximal variable to predict disease management behaviours. Strengths of this investigation include the recruitment of the largest, longitudinal studies of exercise in VLU patients to date. To the best of our knowledge, this is the only study that has examined the influence of several social cognitive constructs on exercise participation in VLU patients simultaneously.

The conceptual framework based on SCT was thus found to be appropriate for an exercise programme to promote healing. The framework’s proposed relationships between OEE and individual psychosocial and physiological factors, self-care behaviours and wound healing outcomes were supported by the results from the RCT. Use of the framework has demonstrated that in addition to wound-specific variables known to be risk factors for healing (e.g. ulcer size, duration of ulcer), many physical, psychosocial and self-care activity factors are extremely important in the healing of VLUs. The findings from this study have important clinical implications for assessing psychosocial factors in VLU patients and modifying intervention targets to improve treatment adherence. Future analyses with larger sample sizes are warranted in order to clarify the relationships between self-efficacy, outcome expectations and depressive symptoms and adherence, both concurrently and over time.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship and/or publication of this article.

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