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Cognitive factors are associated with disability and pain, but not fatigue among physiotherapy attendees with persistent pain and fatigue
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Cognitive factors are associated with disability and pain, but not fatigue among physiotherapy attendees with persistent pain and fatigue Dave P. Thompson a,b,c,∗ , Deborah Antcliff a,c,d , Steve R. Woby b,e a
Bury Integrated Pain Service, Radcliffe Primary Care Centre, Northern Care Alliance NHS Group, 69 Church Street West, Radcliffe, Manchester, M26 2SP, UK b School of Health Sciences, University of Salford, Allerton Building, Salford, Manchester, M6 6PU, UK c Department of Physiotherapy, Northern Care Alliance NHS Group, Fairfield General Hospital, Rochdale Old Road, Bury, Greater Manchester, BL9 7TD, UK d School of Healthcare, Faculty of Medicine and Health, Baines Wing, University of Leeds, Leeds, LS2 9JT, UK e Department of Research and Innovation, Northern Care Alliance NHS Group, Summerfield House, 544 Eccles New Road, Salford, Greater Manchester, M5 5AP, UK
Abstract Objectives Most research exploring the relationship between cognitive factors and pain, disability and fatigue in patients with persistent pain/fatigue has been performed in multi disciplinary environments. It is unclear whether these associations are consistent in other contexts. This study therefore aimed to establish the relationships between these factors in patients with persistent pain/fatigue referred for physiotherapy treatment. Design Cross-sectional observational study assessing the association between cognitive factors (self-efficacy and catastrophizing) and levels of pain, disability, mental fatigue and physical fatigue in patients with persistent pain/fatigue disorders. Data were analysed using regression analyses. Setting Two out-patient physiotherapy departments, Manchester, UK. Participants 166 patients with persistent pain and fatigue disorders chronic widespread pain, fibromyalgia and chronic fatigue syndrome/myalgic encephalopathy). Main outcome measures Disability was assessed using the Fibromyalgia Impact Questionnaire, whilst mental and physical fatigue were assessed with the sub-scales of the Chalder Fatigue Scale. Pain intensity was measured with a Numeric Pain Rating Scale, self-efficacy with the Chronic Pain Self-efficacy Questionnaire and catastrophizing with the Pain Catastrophizing Scale. Results Cognitive factors were significantly associated with pain (self-efficacy beliefs β = −0.30, P < 0.05; catastrophizing β = 0.24, P < 0.05) and disability (self-efficacy beliefs β = −0.62, P < 0.05), but not fatigue. Conclusions Similar associations were observed in patients referred to physiotherapy as to those observed in patients treated in multi disciplinary clinical environments. Self-efficacy beliefs appear to be particularly strong determinants of disability, but exert a lesser influence over pain or fatigue. Targeting self-efficacy may be an effective method to reduce disability in patients with persistent pain and fatigue disorders. Crown Copyright © 2019 Published by Elsevier Ltd on behalf of Chartered Society of Physiotherapy. All rights reserved.
Keywords: Chronic pain; Fatigue; Catastrophization; Self-efficacy; Rehabilitation
Introduction ∗ Corresponding author at: Department of Physiotherapy, Fairfield General Hospital, Rochdale Old Road, Bury, Greater Manchester, BL9 7TD, UK. E-mail address: [email protected] (D.P. Thompson).
Persistent widespread pain disorders are common within the general population [1] and are frequently encoun-
https://doi.org/10.1016/j.physio.2019.01.006 0031-9406/Crown Copyright © 2019 Published by Elsevier Ltd on behalf of Chartered Society of Physiotherapy. All rights reserved.
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tered in physiotherapy practice. Such patients commonly experience co-existing physical and mental fatigue and significant levels of functional impairment [2]. People are given varying diagnoses, such as fibromyalgia, chronic fatigue syndrome/myalgic encephalopathy (CFS/ME) or chronic widespread pain to account for their ongoing symptoms. Previous authors have suggested that there is considerable overlap between these conditions and all can be classified as somatic symptom disorders [3,4]. There is rarely an identifiable pathological cause for persistent pain disorders and no known cure exists. Treatment is therefore often aimed around managing symptoms and maximising functional abilities [5]. It is therefore imperative to identify factors that are related to symptoms and levels of disability in these patients as this will help to inform the further refinement and optimisation of treatments developed to treat persistent pain disorders. Interestingly, previous research has suggested that certain cognitive variables are related to greater disability and pain in these patients, with higher catastrophizing [6] and lower self-efficacy beliefs [7] appearing to be particularly important. However, much of the previous literature exploring these associations in patients with persistent widespread pain/fatigue has been carried out in multi disciplinary pain clinic environments. Patients with persistent pain/fatigue are also frequently encountered in a physiotherapy environment and it is important to understand whether similar associations are observed amongst patients attending physiotherapy as those presenting in MDT environments. It is feasible that patients referred to physiotherapy may present differently due to differing expectations or perceptions of treatment. For example, patients encountered in physiotherapy may be more engaged with the concept of active rehabilitation and therefore cognitive variables may exert a lesser influence. Conversely, patients may attend physiotherapy with expectations of passive treatment and factors such as self-efficacy beliefs may therefore exert a greater influence. Alternatively, similar associations may be evident to those described previously in a non-physiotherapy context. However, as there is currently a paucity of evidence specifically exploring these associations, further investigation is warranted. Indeed, previous authors have highlighted the need to explore these relationships in different treatment contexts, such as in physiotherapy care [7]. It is also noteworthy that previous studies have demonstrated that physiotherapist-led interventions in other musculoskeletal conditions are effective in modifying these variables and that change in these cognitive factors was directly related to improvements in clinical outcome [8]. It is possible that similar physiotherapist-led interventions may be effective in treating patients with persistent widespread pain/fatigue. However, it first is important to establish whether these cognitive variables are significantly associated with pain, fatigue and disability prior to assessing the efficacy of such treatments. The aim of this study was therefore to establish whether levels of catastrophizing and self-efficacy
were related to levels of pain, disability and fatigue in patients with persistent pain and fatigue disorders treated in a physiotherapy environment.
Methods Design A cross-sectional observation study. Setting Out-patients physiotherapy service, Manchester, UK. Participants All participants who were referred with a diagnosis of CFS/ME, chronic widespread pain or fibromyalgia were invited to participate in the study. All participants had been assessed by a rheumatologist who had excluded any pathological cause for symptoms, such as inflammatory disorder, cardio-respiratory disorder, neurological disorder, sleep apnoea, vitamin deficiency, infection or anaemia. All participants were aged over 18 and had experienced symptoms for a minimum of three months. Data collection Data were collected prior to patients commencing physiotherapy. Patients were posted a contact letter asking them to arrange an assessment. Included with this letter were an invitation to participate and an information booklet explaining the aims of the study. Those who agreed to participate signed a consent form and then completed a short self-assessment booklet assessing a number of clinical outcomes. Patients agreeing to participate in the study, together with those who declined to participate then received assessment and treatment as per usual care. Measures Demographics Data were collected for a range of demographic variables, including participants’ age, sex, symptom duration and employment status. Disability Disability was measured with the Fibromyalgia Impact Questionnaire (FIQ) physical impairment sub-scale [9]. The FIQ is an 11 item measure which assesses participants’ ability to engage in normal functional activities. The FIQ is scored by summing the responses for each question and then dividing by the number of questions answered. This score is then multiplied by 3.33 to give a final score of between 0 to 10. Higher
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scores represent greater levels of disability. The psychometric properties of the FIQ have been shown to be acceptable [9]. Pain Pain was measured with an eleven point numeric rating scale (NPRS), a validated tool for use in chronic pain populations which has demonstrated excellent psychometric properties [10]. The scale was anchored 0 “no pain” and 10 “worst possible pain.” Fatigue Fatigue was measured using the Chalder Fatigue Scale (CF), an 11 item measure of fatigue. The scale consists of two sub-scales, which measure physical fatigue (CF-p) and mental fatigue (CF-m) [11]. The Physical fatigue subscale contains 7 items and scores range between 0 to 21. The mental fatigue subscale contains 4 items and scores range between 0 to 12, with greater scores representing greater levels of fatigue. The CF has demonstrated good psychometric properties [11,12]. Catastrophizing Catastrophizing is an excessively negative orientation towards pain, whereby people ruminate excessively about pain, magnify the negative consequences and feel helpless to improve their symptoms [13]. It was measured using the Pain Catastrophizing Scale (PCS) [13], a 13 item measure with scores ranging from 0 to 62. Higher scores represent greater levels of catastrophizing. The PCS has good internal consistency and validity [14,15]. Chronic Pain Self-efficacy Questionnaire: physical function sub-scale (CPSS-pf) Functional self-efficacy beliefs are a person’s confidence in being able to successfully complete a physical task. It was measured using the modified version of Chronic Pain Selfefficacy Questionnaire physical function sub-scale (CPSS) developed by Woby and colleagues [16]. This version of the CPSS has also been shown to possess excellent test–retest reliability and internal consistency. The scale has 9 items and scores range from 0 to 72, with higher scores representing greater confidence in performing physical activities. Analyses Data were analysed using IBM SPSS Statistics 22 (IBM Corporation, Armonk, NY). Demographic data were analysed using descriptive analyses, the associations between cognitive factors and symptoms and disability were analysed using simple correlations and regression analyses [17].
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patients. Patients’ personal data were anonymised throughout data analysis. Sample size According to the criteria suggested by Tabachnick and Fidell [18], 122 participants would be required for a regression analyses with nine explanatory variables. Recruitment rates for similar studies in the participating physiotherapy department were typically around 40%. To additionally allow for a 10% drop-out rate after initially consenting, 340 patients were approached. Missing data In instances when data were missing for individual items on a questionnaire the mean value for the remaining items on the scale was imputed in its place. If more than 10% of data were missing for any then that questionnaire was excluded from the analyses. When whole questionnaires were missing, data were analysed using pairwise exclusion, so that data for the remaining scales in the questionnaire booklets could be included in the analyses and thus minimise the risk of bias [17]. Simple correlations Pearson’s correlations were calculated between dependent and independent variables. Correlations with a P value <0.05 were considered significant. Regression analyses Four regression analyses were performed, with pain, disability, physical fatigue and mental fatigue as the dependent variables in each analysis. When pain and fatigue were not the dependent variables they were entered into the analyses as co-variates. For each analysis Durbin–Watson values, variance inflation factors (VIF) and standardised residuals were assessed to ensure that the assumption of independence of errors was met, there were no issues with multicollinearity and that no cases exerted undue influence on the results [17]. Analyses were performed in a stepwise fashion. In the first step demographic factors were entered (age, sex and symptom duration), followed by pain, physical fatigue and mental fatigue (when not dependent variables) in the second step. The cognitive variables were then entered in the final step, after the other variables had been controlled for. Standardised B values were examined for the final model to allow the strength of the relationship of each factor to the dependent variable to be established when all variables were considered.
Results Participants
Bias The researchers performing data analyses were not involved in data collection, assessment or treatment of
340 patients were invited to participate, of whom 167 agreed to participate (49%). There were more females (87%) than male participants (13%) and the ages ranged between
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Table 1 Demographic characteristics of participants (n = 166). Variable
Mean (SD)
Frequency (%)
Table 3 Regression analyses showing the cross-sectional relationship between the cognitive factors and outcome variables (n = 166). Variable
Sex Female Male Not working due to symptoms Age (years) Mean duration off work (months) Symptom duration (months) Disability (FIQ) Pain (NPRS) Physical fatigue (CF-p) Mental fatigue (CF-m) Self-efficacy (CPSS) Catastrophizing (PCS)
Outcome: disability 1. Age Sex Symptom duration 2. Pain intensity Physical fatigue Mental fatigue 3. Self-efficacy Catastrophizing
145 (87) 21 (13) 82 (49) 49 (11) 72 (80) 91 (81) 5.1 (2.3) 4.2 (2.2) 15 (4.8) 7 (2.8) 28 (16) 27 (12)
FIQ = Fibromyalgia Impact Questionnaire; NPRS = Numeric Pain Rating Scale; CF-p = Chalder Fatigue Scale physical sub-scale; CF-m = Chalder Fatigue Scale mental subscale; CPSS = Chronic Pain Self-efficacy Scale; PCS = Pain Catastrophizing Scale.
18 to 69 years. The demographic characteristics of the sample are summarised in Table 1. Complete data were provided by 152 patients, with partial data available for the remaining 15. Missing data were managed by pairwise exclusion as discussed previously. Pearson’s correlations Table 2 demonstrates the bi-variate correlations between the variables entered into the regression model. Selfefficacy was significantly associated with demographics, with older people reporting lower self-efficacy beliefs. Higher self-efficacy was also significantly associated with lower disability, pain, and mental and physical fatigue. Catastrophizing was not significantly associated with any of the demographic variables, but higher catastrophizing was associated with higher disability, pain, physical fatigue and mental fatigue. Regression analyses Durbin–Watson values, VIF and standardised residuals were all within acceptable limits, suggesting that the assumption of independence of errors was met and there were no problems with multicollinearity. Skewness and kurtosis variables were less than +/−1, suggesting skewness and kurtosis
Outcome: pain intensity 1. Age Sex Symptom duration 2. Physical fatigue Mental fatigue 3. Self-efficacy Catastrophizing Outcome: physical fatigue 1. Age Sex Symptom duration 2. Pain Mental fatigue 3. Self-efficacy Catastrophizing Outcome: mental fatigue 1. Age Sex Symptom duration 2. Pain Physical fatigue 3. Self-efficacy Catastrophizing *
R2
R2 change
β
0.06
0.06*
0.31
0.25*
0.57
0.26*
0.02 0.05 −0.04 0.25* 0.05 0.06 −0.62* 0.16
0.04
0.04
0.10
0.06*
0.24
0.14*
0.02
0.02
0.43
0.41*
0.45
0.02
0.01
0.09 0.02 0.06 0.09 0.01 −0.30* 0.20* −0.05 −0.06 −0.13 0.06 0.56* −0.13 −0.07 0.01
0.41
0.40*
0.42
0.01*
0.03 −0.01 0.08 0.01 0.58* −0.13 0.03
P < 0.05.
with within acceptable limits. Table 3 shows the final regression models with pain, disability, mental fatigue and physical fatigue as the dependent variables. When disability was the dependent variable, higher pain intensity was significantly associated with greater disability (R2 = 0.25, P < 0.05). However, even after controlling for this, cognitive factors explained an additional 26% of variance in disability. In the final model only greater pain intensity (β = 0.25, P < 0.05) and lower self-efficacy beliefs
Table 2 Correlations between variables. Variable
Age
Symptom duration
Age Symptom duration Disability Pain Physical fatigue Mental fatigue Self-efficacy Catastrophizing
–
0.4* – 0.0 0.1 −0.1 0.0 0.0 0.0
*
0.4* 0.1 0.2* −0.1 0.1 −0.2* 0.1
Disability 0.1 0.0 – 0.5* 0.3* 0.3* −0.7* 0.2*
Pain
Physical fatigue
0.2* 0.1 0.5* – 0.2* 0.3* −0.4* 0.4*
−0.1 −0.1 0.3* 0.2* – 0.7* −0.3* 0.3*
Mental fatigue 0.1 0.0 0.3* 0.3* 0.7* – −0.4* 0.3*
Self-efficacy
Catastrophizing
−0.2* 0.0 −0.7* −0.4* −0.3* −0.4* – 0.3*
0.1 0.0 0.2* 0.4* 0.3* 0.3* −0.3* –
P < 0.05.
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(β = −0.62, P < 0.05) were associated with greater levels of disability. In the fatigue analyses, cognitive factors did not explain significant variance in physical fatigue and only explained 1% of the variance in mental fatigue, with neither self-efficacy beliefs nor catastrophizing exhibiting a significant β values. There was a strong association between physical and mental fatigue in both analyses. Mental fatigue explained 41% of the variance in physical fatigue (β = 0.56, P < 0.05) and physical fatigue explained 40% of the variance in mental fatigue (β = 0.58, P < 0.05). When pain was the dependent variable, physical and mental fatigue explained 6% of variance in pain intensity, although neither variable exhibited significant β values in the final model. After controlling for demographics and fatigue, the cognitive factors explained an additional 14% of variance in pain, with both catastrophizing (β = 0.2, P < 0.05) and selfefficacy (β = 0.3, P < 0.05) explaining unique variance in the final model.
Discussion This study aimed to establish the relationships between self-efficacy, catastrophizing and levels of pain, disability and fatigue in patients with persistent widespread pain/fatigue who presented for treatment in a physiotherapy environment. The results revealed that cognitive variables were significantly related to levels of disability, with low self-efficacy beliefs demonstrating particularly strong associations with greater disability. Likewise, self-efficacy beliefs and catastrophizing were also associated with pain intensity, albeit to a lesser extent, with lower self-efficacy and greater catastrophizing being associated with greater pain. The association with fatigue was less pronounced however, with no significant associations between the cognitive variables and physical fatigue, and only 1% of variance in mental fatigue explained by self-efficacy and catastrophizing. Moreover, neither selfefficacy nor catastrophizing explained unique variance in either of the fatigue analyses. The strong association between greater self-efficacy beliefs and lower disability is in line with the relationships reported in persistent pain populations treated in other clinical contexts [7]. Moreover, it is similar to those reported in people with other persistent musculoskeletal problems treated in a physiotherapy environment [8,19,20]. It is plausible that patients who lack confidence in their ability to successfully complete functional activities do not attempt to engage in them and thus become increasingly functionally disabled. This has important clinical implications, since enhancing self-efficacy beliefs may result in important reductions in disability. Indeed, previous studies suggest that treatments which directly target self-efficacy beliefs through structured goal setting exercises to gradually increase activity result in important improvements in disability [8]. Evidently, these interventions can be successfully delivered by appropri-
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ately trained physiotherapists and it is feasible that similar associations might be observed in patients with persistent pain/fatigue treated in a physiotherapy environment [8]. In contrast to the aforementioned findings, it would appear that the cognitive variables explored in this study were not strongly related to levels of fatigue. This is in contrast to a previous meta-analysis of the relationship between catastrophizing and fatigue in people with a range of long-term health problems, including both CFS and fibromyalgia [21]. It is noteworthy however, that different catastrophizing measurement tools were employed in several of the studies included in the meta-analysis, with either brief measures or fatiguespecific catastrophizing scales being employed. In contrast, the measure of catastrophizing employed in the current study assessed catastrophizing related to pain. This may suggest that different aspects of catastrophizing may be related to different symptoms and it may be important to use contextspecific measures of catastrophizing in future studies (i.e. if fatigue is the measure of interest, specific measures, such as the Fatigue Catastrophizing Scale [21], should be utilised). These differences in measurement and methodology may account for the differences observed with the current results. Alternatively, it may be that some differences may exist in the factors which contribute to fatigue in patients presenting for physiotherapy treatment and those treated in other contexts. Specifically, it is possible that other factors may be the most important determinants of fatigue in patients treated in a physiotherapy environment. Indeed, a previous study suggested that fear avoidance beliefs may actually be stronger determinants of fatigue in patients with CFS. For example, a sub-analysis of a randomised controlled trial of patients with CFS/ME who were treated with either usual care, graded exercise, cognitive behavioural therapy or adaptive pacing therapy explored factors which had a mediating effect on improvements in fatigue [22]. The study reported that reductions in fear avoidance beliefs and improvements in timed walking distance were the strongest mediators of improvements in fatigue [22]. This would seem to suggest that reducing fears and improving behavioural performance may be more effective than targeting catastrophizing or self-efficacy in patients with long-standing fatigue problems. Future studies in a physiotherapy environment should therefore consider using measures of fear-avoidance and fatigue-specific catastrophizing scales to assess whether similar associations exist in physiotherapy populations. The final outcome measure of interest was pain intensity, with the regression analysis suggesting that both selfefficacy beliefs and catastrophizing contributed to levels of pain. Again, this is line both with previous research of physiotherapy-led chronic pain interventions [8,19,20] and treatment in other contexts [23]. Moreover, although a relatively small amount of variance in pain intensity was explained by cognitive factors, these results may suggest that targeting these variables may be an effective way to reduce pain intensity.
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Limitations
Appendix A. Supplementary data
There are some limitations to this study. Firstly, no measure of pain-related fear was included, which may have led to the relationship between cognitive factors and levels of adjustment being understated. Secondly, the measure of catastrophizing was pain-specific and may not have adequately captured any associations with fatigue. Finally, as the results are cross-sectional they cannot be interpreted as causative.
Supplementary data associated with this article can be found, in the online version, at https://doi.org/10.1016/ j.physio.2019.01.006.
Conclusions Despite the above considerations, this study demonstrates that the associations between cognitive factors and levels of pain and disability in people with persistent pain/fatigue who are referred to physiotherapy are consistent with those observed in other clinical environments. In contrast, some differences may exist in the associations between catastrophizing and levels of fatigue. These are important findings as it supports the hypothesis that physiotherapy-led treatments which are effective for other persistent pain conditions may also be efficacious in those people with persistent widespread pain. Further research is now warranted to explore whether physiotherapy treatment can modify cognitive factors in this group of patients and whether changes in cognitive factors are associated with improvements in clinical outcome.
Key messages • Cognitive factors appear to be important determinants of levels of disability and pain in patients with persistent pain and fatigue disorders who are treated in a physiotherapy context. • Cognitive factors were not associated with levels of physical or mental fatigue in this clinical environment.
Acknowledgements The authors would like to thank the staff at North Manchester General Hospital for their assistance in data collection. Ethical approval: Ethical approval was granted by North Manchester Local Research Ethics Committee (REC reference:04/Q1406/64). Funding: This study was funded by The Pennine Acute Hospitals NHS Trust. Conflicts of interest: None declared.
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Cognitive factors are associated with disability and pain, but not fatigue among physiotherapy attendees with persistent pain and fatigue Dave P. Thompson a,b,c,∗ , Deborah Antcliff a,c,d , Steve R. Woby b,e a
Bury Integrated Pain Service, Radcliffe Primary Care Centre, Northern Care Alliance NHS Group, 69 Church Street West, Radcliffe, Manchester, M26 2SP, UK b School of Health Sciences, University of Salford, Allerton Building, Salford, Manchester, M6 6PU, UK c Department of Physiotherapy, Northern Care Alliance NHS Group, Fairfield General Hospital, Rochdale Old Road, Bury, Greater Manchester, BL9 7TD, UK d School of Healthcare, Faculty of Medicine and Health, Baines Wing, University of Leeds, Leeds, LS2 9JT, UK e Department of Research and Innovation, Northern Care Alliance NHS Group, Summerfield House, 544 Eccles New Road, Salford, Greater Manchester, M5 5AP, UK
Abstract Objectives Most research exploring the relationship between cognitive factors and pain, disability and fatigue in patients with persistent pain/fatigue has been performed in multi disciplinary environments. It is unclear whether these associations are consistent in other contexts. This study therefore aimed to establish the relationships between these factors in patients with persistent pain/fatigue referred for physiotherapy treatment. Design Cross-sectional observational study assessing the association between cognitive factors (self-efficacy and catastrophizing) and levels of pain, disability, mental fatigue and physical fatigue in patients with persistent pain/fatigue disorders. Data were analysed using regression analyses. Setting Two out-patient physiotherapy departments, Manchester, UK. Participants 166 patients with persistent pain and fatigue disorders chronic widespread pain, fibromyalgia and chronic fatigue syndrome/myalgic encephalopathy). Main outcome measures Disability was assessed using the Fibromyalgia Impact Questionnaire, whilst mental and physical fatigue were assessed with the sub-scales of the Chalder Fatigue Scale. Pain intensity was measured with a Numeric Pain Rating Scale, self-efficacy with the Chronic Pain Self-efficacy Questionnaire and catastrophizing with the Pain Catastrophizing Scale. Results Cognitive factors were significantly associated with pain (self-efficacy beliefs β = −0.30, P < 0.05; catastrophizing β = 0.24, P < 0.05) and disability (self-efficacy beliefs β = −0.62, P < 0.05), but not fatigue. Conclusions Similar associations were observed in patients referred to physiotherapy as to those observed in patients treated in multi disciplinary clinical environments. Self-efficacy beliefs appear to be particularly strong determinants of disability, but exert a lesser influence over pain or fatigue. Targeting self-efficacy may be an effective method to reduce disability in patients with persistent pain and fatigue disorders. Crown Copyright © 2019 Published by Elsevier Ltd on behalf of Chartered Society of Physiotherapy. All rights reserved.
Keywords: Chronic pain; Fatigue; Catastrophization; Self-efficacy; Rehabilitation
Introduction ∗ Corresponding author at: Department of Physiotherapy, Fairfield General Hospital, Rochdale Old Road, Bury, Greater Manchester, BL9 7TD, UK. E-mail address: [email protected] (D.P. Thompson).
Persistent widespread pain disorders are common within the general population [1] and are frequently encoun-
https://doi.org/10.1016/j.physio.2019.01.006 0031-9406/Crown Copyright © 2019 Published by Elsevier Ltd on behalf of Chartered Society of Physiotherapy. All rights reserved.
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tered in physiotherapy practice. Such patients commonly experience co-existing physical and mental fatigue and significant levels of functional impairment [2]. People are given varying diagnoses, such as fibromyalgia, chronic fatigue syndrome/myalgic encephalopathy (CFS/ME) or chronic widespread pain to account for their ongoing symptoms. Previous authors have suggested that there is considerable overlap between these conditions and all can be classified as somatic symptom disorders [3,4]. There is rarely an identifiable pathological cause for persistent pain disorders and no known cure exists. Treatment is therefore often aimed around managing symptoms and maximising functional abilities [5]. It is therefore imperative to identify factors that are related to symptoms and levels of disability in these patients as this will help to inform the further refinement and optimisation of treatments developed to treat persistent pain disorders. Interestingly, previous research has suggested that certain cognitive variables are related to greater disability and pain in these patients, with higher catastrophizing [6] and lower self-efficacy beliefs [7] appearing to be particularly important. However, much of the previous literature exploring these associations in patients with persistent widespread pain/fatigue has been carried out in multi disciplinary pain clinic environments. Patients with persistent pain/fatigue are also frequently encountered in a physiotherapy environment and it is important to understand whether similar associations are observed amongst patients attending physiotherapy as those presenting in MDT environments. It is feasible that patients referred to physiotherapy may present differently due to differing expectations or perceptions of treatment. For example, patients encountered in physiotherapy may be more engaged with the concept of active rehabilitation and therefore cognitive variables may exert a lesser influence. Conversely, patients may attend physiotherapy with expectations of passive treatment and factors such as self-efficacy beliefs may therefore exert a greater influence. Alternatively, similar associations may be evident to those described previously in a non-physiotherapy context. However, as there is currently a paucity of evidence specifically exploring these associations, further investigation is warranted. Indeed, previous authors have highlighted the need to explore these relationships in different treatment contexts, such as in physiotherapy care [7]. It is also noteworthy that previous studies have demonstrated that physiotherapist-led interventions in other musculoskeletal conditions are effective in modifying these variables and that change in these cognitive factors was directly related to improvements in clinical outcome [8]. It is possible that similar physiotherapist-led interventions may be effective in treating patients with persistent widespread pain/fatigue. However, it first is important to establish whether these cognitive variables are significantly associated with pain, fatigue and disability prior to assessing the efficacy of such treatments. The aim of this study was therefore to establish whether levels of catastrophizing and self-efficacy
were related to levels of pain, disability and fatigue in patients with persistent pain and fatigue disorders treated in a physiotherapy environment.
Methods Design A cross-sectional observation study. Setting Out-patients physiotherapy service, Manchester, UK. Participants All participants who were referred with a diagnosis of CFS/ME, chronic widespread pain or fibromyalgia were invited to participate in the study. All participants had been assessed by a rheumatologist who had excluded any pathological cause for symptoms, such as inflammatory disorder, cardio-respiratory disorder, neurological disorder, sleep apnoea, vitamin deficiency, infection or anaemia. All participants were aged over 18 and had experienced symptoms for a minimum of three months. Data collection Data were collected prior to patients commencing physiotherapy. Patients were posted a contact letter asking them to arrange an assessment. Included with this letter were an invitation to participate and an information booklet explaining the aims of the study. Those who agreed to participate signed a consent form and then completed a short self-assessment booklet assessing a number of clinical outcomes. Patients agreeing to participate in the study, together with those who declined to participate then received assessment and treatment as per usual care. Measures Demographics Data were collected for a range of demographic variables, including participants’ age, sex, symptom duration and employment status. Disability Disability was measured with the Fibromyalgia Impact Questionnaire (FIQ) physical impairment sub-scale [9]. The FIQ is an 11 item measure which assesses participants’ ability to engage in normal functional activities. The FIQ is scored by summing the responses for each question and then dividing by the number of questions answered. This score is then multiplied by 3.33 to give a final score of between 0 to 10. Higher
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scores represent greater levels of disability. The psychometric properties of the FIQ have been shown to be acceptable [9]. Pain Pain was measured with an eleven point numeric rating scale (NPRS), a validated tool for use in chronic pain populations which has demonstrated excellent psychometric properties [10]. The scale was anchored 0 “no pain” and 10 “worst possible pain.” Fatigue Fatigue was measured using the Chalder Fatigue Scale (CF), an 11 item measure of fatigue. The scale consists of two sub-scales, which measure physical fatigue (CF-p) and mental fatigue (CF-m) [11]. The Physical fatigue subscale contains 7 items and scores range between 0 to 21. The mental fatigue subscale contains 4 items and scores range between 0 to 12, with greater scores representing greater levels of fatigue. The CF has demonstrated good psychometric properties [11,12]. Catastrophizing Catastrophizing is an excessively negative orientation towards pain, whereby people ruminate excessively about pain, magnify the negative consequences and feel helpless to improve their symptoms [13]. It was measured using the Pain Catastrophizing Scale (PCS) [13], a 13 item measure with scores ranging from 0 to 62. Higher scores represent greater levels of catastrophizing. The PCS has good internal consistency and validity [14,15]. Chronic Pain Self-efficacy Questionnaire: physical function sub-scale (CPSS-pf) Functional self-efficacy beliefs are a person’s confidence in being able to successfully complete a physical task. It was measured using the modified version of Chronic Pain Selfefficacy Questionnaire physical function sub-scale (CPSS) developed by Woby and colleagues [16]. This version of the CPSS has also been shown to possess excellent test–retest reliability and internal consistency. The scale has 9 items and scores range from 0 to 72, with higher scores representing greater confidence in performing physical activities. Analyses Data were analysed using IBM SPSS Statistics 22 (IBM Corporation, Armonk, NY). Demographic data were analysed using descriptive analyses, the associations between cognitive factors and symptoms and disability were analysed using simple correlations and regression analyses [17].
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patients. Patients’ personal data were anonymised throughout data analysis. Sample size According to the criteria suggested by Tabachnick and Fidell [18], 122 participants would be required for a regression analyses with nine explanatory variables. Recruitment rates for similar studies in the participating physiotherapy department were typically around 40%. To additionally allow for a 10% drop-out rate after initially consenting, 340 patients were approached. Missing data In instances when data were missing for individual items on a questionnaire the mean value for the remaining items on the scale was imputed in its place. If more than 10% of data were missing for any then that questionnaire was excluded from the analyses. When whole questionnaires were missing, data were analysed using pairwise exclusion, so that data for the remaining scales in the questionnaire booklets could be included in the analyses and thus minimise the risk of bias [17]. Simple correlations Pearson’s correlations were calculated between dependent and independent variables. Correlations with a P value <0.05 were considered significant. Regression analyses Four regression analyses were performed, with pain, disability, physical fatigue and mental fatigue as the dependent variables in each analysis. When pain and fatigue were not the dependent variables they were entered into the analyses as co-variates. For each analysis Durbin–Watson values, variance inflation factors (VIF) and standardised residuals were assessed to ensure that the assumption of independence of errors was met, there were no issues with multicollinearity and that no cases exerted undue influence on the results [17]. Analyses were performed in a stepwise fashion. In the first step demographic factors were entered (age, sex and symptom duration), followed by pain, physical fatigue and mental fatigue (when not dependent variables) in the second step. The cognitive variables were then entered in the final step, after the other variables had been controlled for. Standardised B values were examined for the final model to allow the strength of the relationship of each factor to the dependent variable to be established when all variables were considered.
Results Participants
Bias The researchers performing data analyses were not involved in data collection, assessment or treatment of
340 patients were invited to participate, of whom 167 agreed to participate (49%). There were more females (87%) than male participants (13%) and the ages ranged between
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Table 1 Demographic characteristics of participants (n = 166). Variable
Mean (SD)
Frequency (%)
Table 3 Regression analyses showing the cross-sectional relationship between the cognitive factors and outcome variables (n = 166). Variable
Sex Female Male Not working due to symptoms Age (years) Mean duration off work (months) Symptom duration (months) Disability (FIQ) Pain (NPRS) Physical fatigue (CF-p) Mental fatigue (CF-m) Self-efficacy (CPSS) Catastrophizing (PCS)
Outcome: disability 1. Age Sex Symptom duration 2. Pain intensity Physical fatigue Mental fatigue 3. Self-efficacy Catastrophizing
145 (87) 21 (13) 82 (49) 49 (11) 72 (80) 91 (81) 5.1 (2.3) 4.2 (2.2) 15 (4.8) 7 (2.8) 28 (16) 27 (12)
FIQ = Fibromyalgia Impact Questionnaire; NPRS = Numeric Pain Rating Scale; CF-p = Chalder Fatigue Scale physical sub-scale; CF-m = Chalder Fatigue Scale mental subscale; CPSS = Chronic Pain Self-efficacy Scale; PCS = Pain Catastrophizing Scale.
18 to 69 years. The demographic characteristics of the sample are summarised in Table 1. Complete data were provided by 152 patients, with partial data available for the remaining 15. Missing data were managed by pairwise exclusion as discussed previously. Pearson’s correlations Table 2 demonstrates the bi-variate correlations between the variables entered into the regression model. Selfefficacy was significantly associated with demographics, with older people reporting lower self-efficacy beliefs. Higher self-efficacy was also significantly associated with lower disability, pain, and mental and physical fatigue. Catastrophizing was not significantly associated with any of the demographic variables, but higher catastrophizing was associated with higher disability, pain, physical fatigue and mental fatigue. Regression analyses Durbin–Watson values, VIF and standardised residuals were all within acceptable limits, suggesting that the assumption of independence of errors was met and there were no problems with multicollinearity. Skewness and kurtosis variables were less than +/−1, suggesting skewness and kurtosis
Outcome: pain intensity 1. Age Sex Symptom duration 2. Physical fatigue Mental fatigue 3. Self-efficacy Catastrophizing Outcome: physical fatigue 1. Age Sex Symptom duration 2. Pain Mental fatigue 3. Self-efficacy Catastrophizing Outcome: mental fatigue 1. Age Sex Symptom duration 2. Pain Physical fatigue 3. Self-efficacy Catastrophizing *
R2
R2 change
β
0.06
0.06*
0.31
0.25*
0.57
0.26*
0.02 0.05 −0.04 0.25* 0.05 0.06 −0.62* 0.16
0.04
0.04
0.10
0.06*
0.24
0.14*
0.02
0.02
0.43
0.41*
0.45
0.02
0.01
0.09 0.02 0.06 0.09 0.01 −0.30* 0.20* −0.05 −0.06 −0.13 0.06 0.56* −0.13 −0.07 0.01
0.41
0.40*
0.42
0.01*
0.03 −0.01 0.08 0.01 0.58* −0.13 0.03
P < 0.05.
with within acceptable limits. Table 3 shows the final regression models with pain, disability, mental fatigue and physical fatigue as the dependent variables. When disability was the dependent variable, higher pain intensity was significantly associated with greater disability (R2 = 0.25, P < 0.05). However, even after controlling for this, cognitive factors explained an additional 26% of variance in disability. In the final model only greater pain intensity (β = 0.25, P < 0.05) and lower self-efficacy beliefs
Table 2 Correlations between variables. Variable
Age
Symptom duration
Age Symptom duration Disability Pain Physical fatigue Mental fatigue Self-efficacy Catastrophizing
–
0.4* – 0.0 0.1 −0.1 0.0 0.0 0.0
*
0.4* 0.1 0.2* −0.1 0.1 −0.2* 0.1
Disability 0.1 0.0 – 0.5* 0.3* 0.3* −0.7* 0.2*
Pain
Physical fatigue
0.2* 0.1 0.5* – 0.2* 0.3* −0.4* 0.4*
−0.1 −0.1 0.3* 0.2* – 0.7* −0.3* 0.3*
Mental fatigue 0.1 0.0 0.3* 0.3* 0.7* – −0.4* 0.3*
Self-efficacy
Catastrophizing
−0.2* 0.0 −0.7* −0.4* −0.3* −0.4* – 0.3*
0.1 0.0 0.2* 0.4* 0.3* 0.3* −0.3* –
P < 0.05.
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(β = −0.62, P < 0.05) were associated with greater levels of disability. In the fatigue analyses, cognitive factors did not explain significant variance in physical fatigue and only explained 1% of the variance in mental fatigue, with neither self-efficacy beliefs nor catastrophizing exhibiting a significant β values. There was a strong association between physical and mental fatigue in both analyses. Mental fatigue explained 41% of the variance in physical fatigue (β = 0.56, P < 0.05) and physical fatigue explained 40% of the variance in mental fatigue (β = 0.58, P < 0.05). When pain was the dependent variable, physical and mental fatigue explained 6% of variance in pain intensity, although neither variable exhibited significant β values in the final model. After controlling for demographics and fatigue, the cognitive factors explained an additional 14% of variance in pain, with both catastrophizing (β = 0.2, P < 0.05) and selfefficacy (β = 0.3, P < 0.05) explaining unique variance in the final model.
Discussion This study aimed to establish the relationships between self-efficacy, catastrophizing and levels of pain, disability and fatigue in patients with persistent widespread pain/fatigue who presented for treatment in a physiotherapy environment. The results revealed that cognitive variables were significantly related to levels of disability, with low self-efficacy beliefs demonstrating particularly strong associations with greater disability. Likewise, self-efficacy beliefs and catastrophizing were also associated with pain intensity, albeit to a lesser extent, with lower self-efficacy and greater catastrophizing being associated with greater pain. The association with fatigue was less pronounced however, with no significant associations between the cognitive variables and physical fatigue, and only 1% of variance in mental fatigue explained by self-efficacy and catastrophizing. Moreover, neither selfefficacy nor catastrophizing explained unique variance in either of the fatigue analyses. The strong association between greater self-efficacy beliefs and lower disability is in line with the relationships reported in persistent pain populations treated in other clinical contexts [7]. Moreover, it is similar to those reported in people with other persistent musculoskeletal problems treated in a physiotherapy environment [8,19,20]. It is plausible that patients who lack confidence in their ability to successfully complete functional activities do not attempt to engage in them and thus become increasingly functionally disabled. This has important clinical implications, since enhancing self-efficacy beliefs may result in important reductions in disability. Indeed, previous studies suggest that treatments which directly target self-efficacy beliefs through structured goal setting exercises to gradually increase activity result in important improvements in disability [8]. Evidently, these interventions can be successfully delivered by appropri-
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ately trained physiotherapists and it is feasible that similar associations might be observed in patients with persistent pain/fatigue treated in a physiotherapy environment [8]. In contrast to the aforementioned findings, it would appear that the cognitive variables explored in this study were not strongly related to levels of fatigue. This is in contrast to a previous meta-analysis of the relationship between catastrophizing and fatigue in people with a range of long-term health problems, including both CFS and fibromyalgia [21]. It is noteworthy however, that different catastrophizing measurement tools were employed in several of the studies included in the meta-analysis, with either brief measures or fatiguespecific catastrophizing scales being employed. In contrast, the measure of catastrophizing employed in the current study assessed catastrophizing related to pain. This may suggest that different aspects of catastrophizing may be related to different symptoms and it may be important to use contextspecific measures of catastrophizing in future studies (i.e. if fatigue is the measure of interest, specific measures, such as the Fatigue Catastrophizing Scale [21], should be utilised). These differences in measurement and methodology may account for the differences observed with the current results. Alternatively, it may be that some differences may exist in the factors which contribute to fatigue in patients presenting for physiotherapy treatment and those treated in other contexts. Specifically, it is possible that other factors may be the most important determinants of fatigue in patients treated in a physiotherapy environment. Indeed, a previous study suggested that fear avoidance beliefs may actually be stronger determinants of fatigue in patients with CFS. For example, a sub-analysis of a randomised controlled trial of patients with CFS/ME who were treated with either usual care, graded exercise, cognitive behavioural therapy or adaptive pacing therapy explored factors which had a mediating effect on improvements in fatigue [22]. The study reported that reductions in fear avoidance beliefs and improvements in timed walking distance were the strongest mediators of improvements in fatigue [22]. This would seem to suggest that reducing fears and improving behavioural performance may be more effective than targeting catastrophizing or self-efficacy in patients with long-standing fatigue problems. Future studies in a physiotherapy environment should therefore consider using measures of fear-avoidance and fatigue-specific catastrophizing scales to assess whether similar associations exist in physiotherapy populations. The final outcome measure of interest was pain intensity, with the regression analysis suggesting that both selfefficacy beliefs and catastrophizing contributed to levels of pain. Again, this is line both with previous research of physiotherapy-led chronic pain interventions [8,19,20] and treatment in other contexts [23]. Moreover, although a relatively small amount of variance in pain intensity was explained by cognitive factors, these results may suggest that targeting these variables may be an effective way to reduce pain intensity.
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Limitations
Appendix A. Supplementary data
There are some limitations to this study. Firstly, no measure of pain-related fear was included, which may have led to the relationship between cognitive factors and levels of adjustment being understated. Secondly, the measure of catastrophizing was pain-specific and may not have adequately captured any associations with fatigue. Finally, as the results are cross-sectional they cannot be interpreted as causative.
Supplementary data associated with this article can be found, in the online version, at https://doi.org/10.1016/ j.physio.2019.01.006.
Conclusions Despite the above considerations, this study demonstrates that the associations between cognitive factors and levels of pain and disability in people with persistent pain/fatigue who are referred to physiotherapy are consistent with those observed in other clinical environments. In contrast, some differences may exist in the associations between catastrophizing and levels of fatigue. These are important findings as it supports the hypothesis that physiotherapy-led treatments which are effective for other persistent pain conditions may also be efficacious in those people with persistent widespread pain. Further research is now warranted to explore whether physiotherapy treatment can modify cognitive factors in this group of patients and whether changes in cognitive factors are associated with improvements in clinical outcome.
Key messages • Cognitive factors appear to be important determinants of levels of disability and pain in patients with persistent pain and fatigue disorders who are treated in a physiotherapy context. • Cognitive factors were not associated with levels of physical or mental fatigue in this clinical environment.
Acknowledgements The authors would like to thank the staff at North Manchester General Hospital for their assistance in data collection. Ethical approval: Ethical approval was granted by North Manchester Local Research Ethics Committee (REC reference:04/Q1406/64). Funding: This study was funded by The Pennine Acute Hospitals NHS Trust. Conflicts of interest: None declared.
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