Differences in psychological factors,disability and fatigue according to the grade of chronification in non-specific low back pain patients: A cross-sectional study
Available accessResearch articleFirst published online November, 2020
Differences in psychological factors,disability and fatigue according to the grade of chronification in non-specific low back pain patients: A cross-sectional study
Differences in pain processing, muscle structure and function have been reported in patients with low back pain (LBP) with different grades of pain chronicity.
OBJECTIVE:
The present study aims to examine differences in psychological factors, disability and subjective fatigue between subgroups of LBP based on their chronification grade.
METHODS:
Twenty-one healthy controls (HC) and 54 LBP patients (categorized based on the grades of chronicity into recurrent LBP (RLBP), non-continuous chronic LBP (CLBP), or continuous (CLBP)) filled out a set of self-reporting questionnaires.
RESULTS:
The Hospital Anxiety and Depression Scale (HADS) and Multidimensional Pain Inventory (MPI) scores indicated that anxiety, pain severity, pain interference and affective distress were lower in HC and RLBP compared to non-continuous CLBP. Anxiety scores were higher in non-continuous CLBP compared to RLBP, continuous CLBP and HC. The Pain Catastrophizing Scale for Helplessness (PSCH) was higher in non-continuous CLBP compared to HC. The Survey of Pain Attitudes (SOPA) showed no differences in adaptive and maladaptive behaviors across the groups. The Pain Disability Index (PDI) measured a higher disability in both CLBP groups compared to HC. Moreover, the Rolland Morris Disability Questionnaire (RMDQ) showed higher levels of disability in continuous CLBP compared to non-continuous CLBP, RLBP and HC. The Checklist Individual Strength (CIS) revealed that patients with non-continuous CLBP were affected to a higher extent by severe fatigue compared to continuous CLBP, RLBP and HC (subjective fatigue, concentration and physical activity). For all tests, a significance level of 0.05 was used.
CONCLUSIONS:
RLBP patients are more disabled than HC, but have a tendency towards a general positive psychological state of mind. Non-continuous CLBP patients would most likely present a negative psychological mindset, become more disabled and have prolonged fatigue complaints. Finally, the continuous CLBP patients are characterized by more negative attitudes and believes on pain, enhanced disability and interference of pain in their daily lives.
Non-specific low back pain (LBP) is a highly heterogeneous and multifactorial disorder [1]. Therefore, the course of LBP can vary from patient to patient. Studies have attempted to classify LBP based on symptom duration into (sub)acute, recurrent or chronic LBP (CLBP) [2, 3, 4]. While (sub)acute LBP refers to a first time episode of LBP not exceeding 12 weeks in duration [3, 5], the LBP symptoms reoccur and persist after this period in cases of recurrent (RLBP) and CLBP. A common feature of RLBP is short LBP episodes with high remission rates. [6]. These short LBP episodes are alternated by long periods of symptom remission [7], whereas in CLBP these long remission periods dissipate. Although the LBP intensity fluctuates in CLBP, the symptoms are present on a weekly basis [4, 5]. Specific differences between RLBP and CLBP have seldom been investigated, but recent research has pictured distinctive characteristics between these groups with regard to pain processing, muscle function and muscle structure [8]. Moreover, a recent study suggested that there are distinct subdivisions within the CLBP population [8]. Differentiating between non-continuous and continuous CLBP can further help unravel the complexity of CLBP [9]. Patients with non-continuous CLBP experience alternating painful and pain free days, whereas patients with continuous CLBP report pain complaints on a daily basis.
The influence of psychological factors has shown to play an important role in the evolution from (sub)acute pain to CLBP [10, 11] and in the treatment prognosis of patients with CLBP [12, 13]. Inversely, persistent or reoccurring pain can modify an individual’s beliefs and attitudes [14, 15]. Consequently, inaccurate and negative cognitions lead to negative emotions, which in turn will result into negative attitudes and/or maladaptive behaviours [16, 17]. The latter will conduct the development of new negative cognitions or reinforce negative cognitions which are already present, resulting in a viscious cycle [18]. Psychological factors have also shown to have a substantial impact on pain-related disability and to have affected activities of daily living in LBP [19, 20]. Furthermore, physical functioning in LBP is also affected by fatigue [21]. It has been shown that CLBP patients experience higher levels of fatigue compared to healthy people [11, 22], and there is moderate evidence supporting a relationship between fatigue and LBP intensity and/or LBP-related disability [21]. However, little is known about the relationship between the levels of fatigue and the degree of chronicity [8, 23].
Since psychological factors, fatigue and disability play a role in the chronification of pain, it is of interest to examine the differences in these symptoms that reoccur or persist in the LBP patients. To date, no studies have compared whether psychological factors, fatigue levels and degree of disability differ between patients with non-continuous CLBP and continuous CLBP. Given that there are clinical and experimental differences between RLBP and CLBP, and that there are suggestions that non-continuous CLBP and continuous CLBP should be differentiated, this study therefore focuses on examining differences in psychological factors, disability and fatigue within these sub-classifications of LBP. Considering that the degree of chronicity increases from RLBP to non-continuous CLBP to continuous CLBP, the influence of chronicity is studied by comparing the patients in these groups, as well as members of the LBP free healthy control groups. It is hypothesized that psychological health, disability and fatigue levels (1) would be similar in patients with RLBP as in healthy people, but (2) more affected in those with CLBP and (3) would be affected to a greater extent among those with longer and more continuous complaints.
Methods
Participants
This study comprised male and female individuals with non-specific LBP, and LBP free individuals between 18 and 65 years of age. In total 75 participants were included. Exclusion criteria included pregnancy, 1 year post-natal, (a history of) having neurological, respiratory, circulatory, severe orthopedic or internal diseases. Online advertisements were distributed on social media, and in local hospitals and private practices of PTs and MDs in order to reach the potential participants for the study. Both healthy persons, as well as patients with LBP, were included after the eligibility criteria for participation were checked. If a patient was found eligble for one of the subgroups, an assessment was scheduled.
In- and exclusion criteria of all subjects
Group
HC
RLBP
Non-continuous CLBP
Continuous CLBP
General in- and
exclusion criteria
– Males and females
– 18–65 years old
– 1 years post-natal
– No neurological, respiratory, circulatory or severe, orthopaedic diseases
– No pregnancy
– No back surgery
– No previous cognitive exercise therapy for their low back pain
– No use of antidepressants or analgesics (except for NSAID’s or paracetamol), taken two weeks prior to the testing
Specific in- andexclusion criteria
Healthy persons
No physical pain complaints
Never asked for help or advice concerning low back pain
HC healthy control, RLBP recurrent low back pain, CLBP chronic low back pain, NRS Numeric Rating Scale. at least, NSAID non-steroidal anti-inflammatory drug.
Eligible participants were profoundly questioned about their LBP complaints and classified by the assessor, a physiotherapist with clinical experience, based on their LBP characteristics: the duration and frequency of a pain flare, and the duration of pain free episode. As a result, three subgroups of LBP were created:
A RLBP group with participants with a pain flare of at least 24 hours, followed by a pain free episode of at least one month [7]. A pain flare refers to an increase of 2 points on a Numeric Rating Scale (NRS) and/or a 5 points on the Roland Morris Disability Questionnaire (RMDQ), which persisted 24 hours [24]. A pain flare had to be followed by a pain free episode or remission phase of 1 month during which the LBP would be rated as 0/10 on the NRS and 2 on the RMDQ [25]. The LBP flares need to be present for at least six months [7] and pain flares occur with a frequency of at least two episodes in 12 monts [26]. The RLBP patients included in this study were examined while in a state of remission.
A non-continuous CLBP group with subjects having intermittent complaints of LBP for three to four days a week, for a period of at least three months.
A continuous CLBP group suffering from daily pain complaints for a period of at least three months [8].
The control group consisted of healthy individuals who did not experience any pain complaints at the time when the experiments were taking place and who never experienced LBP complaints of more than 24 hours in the past. They also did never consult a PT or MD because of LBP.
All LBP patients had to suffer from non-specific LBP which is defined as pain in the lumbar region that cannot be attributed to a recognizable, known specific pathology (infection, tumour, osteoporosis, fracture, structural deformity, inflammatory disorders, radicular syndrome or cauda equina syndrome) [27]. Individuals with a history of spinal surgery, spinal deformities, or who have previously received graded activity and motor training (skilled training to cognitively learn to activate the trunk muscles) as treatment for their LBP were also not eligible for participation in this study.
The in- and exclusion criteria can be found in Table 1.
Procedure
This current study is part of a larger investigation [8]. The complete study protocol was approved by the local ethics committee (Ghent University Hospital) and all participants provided written informed consent. The current analysis was designed to determine the differences in psychological characteristics, disability rates and fatigue among continuous CLBP, non-continuous CLBP, RLBP and HC. This will provide insights on how these parameters are influenced by the degree of LBP chronicity.
To evaluate psychological status, degree of disability and fatigue severity, self-reported questionnaires on paper were assessed at the laboratorium of the Department of Physiotherapy, the University of Ghent Hospital. Participants were required to complete the questionnaire. The assessor was present if the participants had questions concerning the questionnaires.
Psychological-related outcome
Hospital Anxiety and Depression Scale (HADS)
The HADS assesses the degree of anxiety and depression during the previous week prior to the assessment [28]. It consists of an anxiety and a depression subscale. Scores from each subscale range between 0 to 21, with a score of 8 or higher indicating the presence of anxiety and depression [29]. The HADS has good internal consistency [30], reliability [29, 30], and validity in a clinical population [30, 31].
Multidimensional Pain Inventory – Part I (MPI-I)
The MPI-I assesses different aspects of pain and their influence on daily life experiences, from a cognitive-behavioral perspective [32, 33]. The instrument contains five subscales, namely pain severity, perceived life control and affective distress, interference with the daily life due to present pain complaints and social support. A higher score on the social support and life control subscales represents a better outcome [34]. A higher score on the subscales interference in daily life, pain severity and affective distress represents a less favourable outcome [34]. The MPI has both good reliability and validity for the LBP patients [32].
Pain Catastrophizing Scale (PCS)
The PCS assesses the catastrophizing of pain and comprises three subscales and a total score [35, 36]. Subscale score ranges are 0–16 for rumination, 0–12 for magnification, and 0–24 for helplessness, and the total score range is 0–52. Scores are clinically relevant for pain catastrophizing when 11 regarding rumination, 5 on magnification, 13 for helplessness and 30 for the total score [37]. The PCS has an acceptable test-retest reliability, internal consistency and predictive validity for patients with chronic pain and LBP [35, 38, 39, 40, 41, 42, 43].
Survey of Pain Attitudes (SOPA)
The SOPA evaluates beliefs and attitudes towards pain [44, 45]. It consists of seven subscales; pain control (0–40 score range), emotion (0–32 score range), pain disability (0–40 score range), medical cure (0–36 score range), physical harm (0–32 score range), medication (0–24 score range) and solicitude (0–24 score range). The first two subscales measure adaptive beliefs, with higher scores on these subscales indicating good adaptive behaviour to pain [46]. The remaining five subscales evaluate maladaptive beliefs and higher scores on these items indicate maladaptive behavior [46]. Scores of 3 on control, 1 on emotion, 38 on disability, 28 on medical cure, 26 on harm, 23 on medication or 20 on solicitude are considered as maladaptive beliefs [46]. The SOPA has a good internal consistency, and moderate to good test-retest reliability and validity for chronic pain patients including those with LBP [44, 45].
Disability-related outcome
Pain Disability Index (PDI)
The PDI evaluates the degree of interruption of activities from daily life due to pain experience in the previous week [47]. The total PDI score ranges between 0 and 70, with higher scores indicating more pain-related disability [47]. The PDI is valid and reliable for patients with chronic pain [47, 48], while total responsiveness for patients with CLBP is good [49].
Between group differences in demographic profile
HC ( 21)
RLBP ( 23)
Non-continuous CLBP ( 15)
Continuous CLBP ( 16)
Gender ()
9♂; 12♀
9♂; 14♀
7♂; 8♀
8♂; 8♀
Age (years)
38.3(13.4)
30.8(9.9)
33.9(10.4)
46.1(14.4)
BMI (kg/m)
23(3.0 )
22.8(2.3)
23.2(1.6)
24.9(2.3)
LBP duration (months)
0
112
104
199
HC healthy control, RLBP recurrent low back pain, CLBP chronic low back pain, number of participants, BMI body mass index, male, female. All values reported as mean (standard deviation). significant difference between HC versus RLBP; significant difference between HC versus continuous CLBP; significant difference between RLBP versus continuous CLBP; significant difference between non-continuous CLBP versus continuous CLBP. The significance level was set at 0.05.
Roland Morris Disability Questionnaire (RMDQ)
This RMDQ evaluates how daily physical activities and functioning are affected by present LBP [50]. The total score ranges from 0 (no disability) to 24 (severe disability), with higher scores indicating higher degrees of LBP-related disability [51]. Internal consistency and test-retest reliability [52, 53], and construct validity [54, 55] of the RMDQ are good.
Fatigue-related outcome
Checklist of Individual Strength (CIS)
The CIS quantifies subjective fatigue and related behavioral aspects experienced during the last two weeks [56, 57]. Four aspects of fatigue are evaluated through the subscales; subjective fatigue (8–56 score range), reduced concentration (5–35 score range), reduced motivation (4–28 score range) and reduced physical activity (3–21 score range). High scores indicate high levels of fatigue and lower levels of concentration, motivation and physical activity [58]. The CIS has a good to excellent validity and reliability in clinical settings among patients with chronic fatigue or chronic diseases, as well as among the healthy population [52, 59, 60].
Psychological, disability and fatigue-related outcomes and between group differences
HC ( 21)
RLBP ( 23)
Non-continuous CLBP ( 15)
Continuous CLBP ( 16)
HADS
Anxiety
2.9
(2.8)
5.3
(3.1)
8.3
(3.0)
5.6
(2.5)
Depression
1.6
(1.9)
2.8
(3.2)
5.2
(3.4)
3.2
(3.8)
MPI
Pain severity
0.1
(0.2)
1.5
(0.8)
2.4
(1.0)
2.7
(0.9)
Interference
0.3
(0.7)
1.2
(0.8)
1.9
(0.7)
2.2
(1.1)
Life control
5
(0.8)
4.4
(0.7)
3.9
(1.1)
4.2
(1.1)
Affective distress
1.1
(1.2)
1.2
(1.1)
2.1
(1.4)
1.8
(1.2)
Social support
3.7
(2.1)
2.7
(1.8)
2.7
(1.7)
2.9
(1.8)
PCS
Rumination
5.1
(3.0)
7.2
(2.9)
7.2
(2.3)
5.9
(3.2)
Magnification
2.5
(1.8)
2.0
(1.6)
2.6
(1.8)
1.9
(1.5)
Helplessness
3.8
(3.9)
5.7
(3.2)
7.4
(2.3)
6.8
(4.7)
Total
11
(7.8)
14.9
(6.1)
17.2
(3.1)
14.5
(8.4)
SOPA
Control about pain
2.4
(0.8)
2.2
(0.6)
2.2
(0.4)
1.8
(0.6)
Emotion
1.8
(0.6)
1.3
(0.7)
1.4
(0.7)
1.0
(0.9)
Pain disability
1.4
(0.7)
1.2
(0.6)
1.5
(0.6)
2.0
(0.7)
Medical cure is possible
2.3
(0.6)
2.1
(0.6)
1.9
(0.6)
1.6
(0.6)
Physical harm
1.4
(0.7)
1.3
(0.5)
1.7
(0.5)
1.6
(0.5)
Medication
2.1
(0.6)
1.8
(0.9)
1.7
(0.6)
1.8
(0.8)
Solicitude
1.3
(0.7)
0.7
(0.5)
1.1
(0.4)
0.7
(0.6)
PDI
Total
4.2
(8.5)
16.8
(10.5)
23.8
(10.0)
27.7
(13.5)
RMDQ
Total
0.2
(0.5)
1.6
(1.4)
4.5
(2.6)
5.8
(2.8)
CIS
Subjective fatigue
18.8
(6.8)
19.0
(5.6)
27.4
(9.8)
22.6
(5.3)
Concentration
10
(4.7)
9.6
(3.7)
17.3
(6.3)
10.5
(5.3)
Motivation
8.7
(3.5)
8.2
(2.8)
11.6
(3.8)
10.4
(4.2)
Physical activity
6.8
(3.3)
8.5
(2.8)
12.7
(4.6)
9.9
(3.6)
All values reported as mean (SD (Standard deviation)). HC healthy control, RLBP recurrent low back pain, CLBP chronic low back pain, number of, HADS Hospital Anxiety and Depression Scale; MPI Multidimensional Pain Inventory; PCS Pain Catastrophizing Scale; SOPA Survey of Pain Attitudes; PDI Pain Disability Index; RMDQ Roland Morris Disability Questionnaire; CIS Checklist Individual Strength. Values are presented as mean (minimum-maximum) and significance is set at 0.05. significant difference between HC versus RLBP; significant difference between HC versus non-continuous CLBP; significant difference between HC versus continuous CLBP; significant difference between RLBP versus non-continuous CLBP; significant difference between RLBP versus continuous CLBP; significant difference between non-continuous CLBP versus continuous CLBP.
Statistical analysis
Statistical analyses were performed using IBM SPSS Statistics 22 (SPP Inc., Chicago, IL, USA). Distribution of the variables was checked by means of observation of the 5% trimmed mean difference, skewness and kurtosis, standard error, and using the Shapiro-Wilk’s test. In case variables were not normally distributed, non-parametric, Kruskal-Wallis H tests were used to examine for group differences, while Mann-Whitney U tests were used for post-hoc pairwise comparison. When variables were normally distributed, a multivariate covariance analysis (MANCOVA) was used for controlling covariates. The psychological, disability and fatigue-related outcomes were selected as dependent variables, while HC, RLBP, non-continuous CLBP and continuous CLBP groups were entered as a fixed factor, due to significant differences between the groups for age, while body mass index (BMI) was added and controlled as covariates. The custom model based on fixed factors and covariates was built for the main effect and interaction. A stepwise backward technique was implemented until only significant variables remained in the model. Wilks Lambda statistics were used to calculate the F-, -values, partial Eta Square () for effect size [61]. Although the recommended overall sample size is bigger ( 179) with power 0.80 and effect size medium ( 0.25), the power is acceptable, as based on the post-hoc power analysis ( 0.59–0.99) and the partial eta square ( 0.09–0.25) from a sample of 75 participants [62]. The overall and group factor interactions were checked to compare the main effects using the Bonferroni post hoc test. The significance was set at 0.05.
Results
Demographic profile
Seventy-five individuals participated in this study and were classified into four predefined groups, namely HC ( 21), RLBP ( 23), non-continuous CLBP ( 15), and continuous CLBP ( 16). No between group differences were seen in gender distribution. The RLBP and non-continuous CLBP groups were significantly younger compared to the continuous CLBP group (Mann-Whitney U: 0.020, 0.021 resp.). The continuous CLBP had a significantly higher BMI compared to the non-continuous CLBP, RLBP or HC (Mann-Whitney U: 0.041, 0.020, 0.029 resp.). The characteristics of every group are presented in Table 2.
Psychological-related outcome
As presented in Table 3, the HADS scores were below the cut-off point (2.9 to 8.3) for all the groups except for the anxiety subscale in the non-continuous CLBP group ( 8). After adjusting for age significant differences were found between groups (Multivariate: 3.36, 0.04, 0.09). The RLBP and the non-continuous CLBP groups reported significantly higher anxiety scores compared to the HC group (Bonferroni: 0.05). However, the anxiety scores of the continuous CLBP group was not significantly different from the HC group. Furthermore, the non-continuous CLBP group had a significantly higher score on the anxiety subscale compared to the other groups (Bonferroni: 0.05). For the depression subscale, only the non-continuous CLBP group reported a significantly higher score than the HC group (Bonferroni: 0.05), and no significant difference was found between the other groups.
Based on the cut-off criteria, most MPI scores showed favourable outcomes for all the groups. The subscales on pain severity (mean score range of 0.1–2.7), pain interference (score range of 0.3–2.2) and affective distress (mean score ranges 1.1–2.1) were below the cut-off points ( 3). Also the subscale on life control (mean score ranges 3.9–5.0) showed a favourable outcome ( 3) for all the groups. For social support however, score were above the cut-off criteria, and thus favourable, in the HC group (mean score 3.7), but not in the three LBP groups (mean score range of 2.7–2.9).
There was an overall difference among the groups on the MPI scores (Multivariate 6.49, 0.001; 0.25). The RLBP, as well as both the CLBP groups, had significantly higher scores on the MPI subscales for pain severity and pain interference as compared to the HC group (Bonferroni: 0.05). A significantly lower score on the life control subscale was reported by both CLBP groups compared to the HC group (Bonferroni: 0.05). For affective distress, only the non-continuous CLBP group scored higher compared to the HC (Bonferroni: 0.05). However, for pain severity, pain interference and affective distress the RLBP group had significantly lower values compared to the non-continuous CLBP group (Bonferroni: 0.05). In addition, the pain severity and pain interference subscales were also significantly lower among the RLBP group compared to continuous the CLBP group (Bonferroni: 0.05). No difference between the LBP groups were found for life control and social support and no significant differences were observed between the non-continuous and continuous CLBP group for any of the MPI subscale (Bonferroni: 0.05).
The results further indicated that the PCS subscales for rumination (mean score range of 5.1–7.2), magnification (mean score range of 1.9–2.6), helplessness (mean score range of 3.8–7.4) as well as the total score (mean score range of 11–17.2) were below the cut-off score for defining pain catastrophizing in all the groups. The total PCS score and subscale scores significantly differed amongst the groups (Multivariate: 1.98, 0.043, 0.08). However, post-hoc analyses showed that only the non-continuous CLBP group reported a significantly higher score on the helplessness subscale compared to the HC group (Bonferroni: 0.03).
The SOPA scores for adaptive behaviours in the subscales for emotion (cut-off: 1; mean score range of 1.0–1.8), pain disability (cut-off: 38; mean score range of 1.2–2.0), medical cure (cut-off: 28; mean score range of 1.6–2.3), physical harm (cut-off: 26; mean score range of 1.3–1.7), medication (cut-off: 23; mean score range of 1.7–2.1) and solicitude (cut-off: 20; mean score range of 0.7–1.1) were favourable for all the groups. However, maladaptive behaviour was reported for on the pain control (cut-off: 1.0; mean score range of 1.8–2.4) in the LBP groups and some of the HC. There were significant differences between groups for the SOPA scores (Multivariate: 2.31, 0.002, 0.20). All LBP groups reported a lower score for solicitude compared to the HC group (Bonferroni: 0.05). The continuous CLBP group had furthermore a significant lower score for pain control, emotion, pain disability and medical cure compared to the HC group (Bonferroni: 0.05). For these four subscales, no significant differences were found between HC and RLBP or non-continuous CLBP. Only a single difference between the LBP groups was found, namely, the continuous CLBP group reported higher scores on pain disability compared to the RLBP (Bonferroni: 0.05). The scores for the physical harm and medication subscales were not significantly different between any of the groups.
Disability-related outcome
The disability status measured by the PDI and RMDQ was significantly different between the groups after controlling age and BMI (Multivariate: 2.10; 0.04, 0.13).
All the groups reported PDI scores (mean score range of 4.2–27.7) that were below the cut-off criteria ( 30) for pain-related disability. The RLBP and both the non-continuous and continuous CLBP groups had significantly higher disability scores on the PDI compared to the HC (Bonferroni: 0.05). No significant differences in PDI scores were seen between the LBP groups.
RMDQ scores (mean score range of 0.5–5.8) were below the cut-off criteria ( 12) for severe disability in all the groups. The RLBP and both groups of CLBP reported a significantly higher RMDQ score compared to the HC group (Bonferroni: 0.05). Furthermore, both CLBP groups showed a significant higher disability score on the RMDQ compared to the RLBP group (Bonferroni: 0.05). However, the RMDQ score did not significantly differ between the continuous and non-continuous CLBP groups.
Fatigue-related outcome
The mean CIS scores for subjective fatigue were lower for the HC, RLBP and continuous CLBP groups compared to the non-continuous CLBP group, which had moderate rates of fatigue severity based on the cut-off criteria. As presented in Table 3, the CIS subscale score and total score were significantly different among all the groups after adjusting for BMI (Multivariate: 3.63; .01, 0.18). The non-continuous CLBP group scored significantly higher compared to the RLBP and HC groups for the subscales of subjective fatigue, concentration and physical activity scores (Bonferroni: 0.05). The concentration subscale was significantly higher in the non-continuous CLBP group compared to the continuous CLBP group (Bonferroni: 0.05). However, the continuous CLBP group did not differ in terms of subjective fatigue, motivation or physical activity compared to the non-continuous CLBP, RLBP or HC group (Bonferroni: 0.05).
Discussion
This study reveals differences in the psychological profiles between LBP groups categorized based on their chronification level. The RLBP patients seem to have a positive psychological state similar to healty persons, although the RLBP have pain and are more disabled, anxious and solitary. The psychological condition of patients with RLBP seems to be in a better condition compared the non-continuous CLBP patients and to a lesser extent compared to the continuous CLBP patients. The continuous CLBP patients only have more pain and disability compared to RLBP patients, whereas the non-continuous CLBP patients in this study are more affected by all aspects of pain interference, disability, anxiety and fatigue compared to RLBP patients. Non-continuous CLBP are also more anxious and have more concentration problems compared to continuous CLBP patients. Continuous CLBP are finally characterized by enhanced maladaptive attitudes and believes, when compared to HC.
As RLBP patients are faced with short pain episodes and long pain free periods, this could explain why they are not psychologically distressed. The inverse might be possible as well, as a positive psychological state of mind in RLBP might have a preventive role in the development of chronicity. However, literature reports that recurring pain can cause a repeated learning experience that may induce changes in pain cognitions and behaviours, which progressively alter and deteriorate RLBP towards CLBP [63]. Donelson et al. [64] reported that a progressive deterioration of pain generators during worsening RLBP is a major cause of developing chronicity in these patients. Thus, although RLBP generally has a positive psychological predisposition, psychological stress can develop during the course of RLBP and facilitate the chronification process. Therefore, therapists should be attentive during treatment for the development of new contributing factors, which might not be present nor apparent during the initial assessment. One must however take into account that the time window which is referred to in some of the questionnaires might have influenced the results of the RLBP group. The included questionnaires assessed emotions, cognitions, symptoms and behaviours at present or during the previous (two) week(s) in which patients with RLBP might not have experienced any LBP due to being in a phase of remission. This might also (in part) explain the lower scores reported by patients with RLBP on psychological outcomes, which could be higher when assessments are taken during an LBP flare.
It is a remarkable result that non-continuous CLBP are more anxious and suffer from a higher degree of concentration problems compared to continuous CLBP. It is possible, a constant uncertainty about when the next pain flare would occur, how severe and disabling it would be, and how long it would last, may predispose patients with non-continuous CLBP to these higher anxiety levels. This is in line with the uncertainty that any future (pain) threat can disrupt and mitigate negative perceptions, and thus increase anxiousness [65]. It is possibly the continuous CLBP were mentally adapted to their pain sensation over time, and this adaptation could have led to pain acceptance, thereby lessening emotional disturbances. Moreover, it is assumed that patients with continuous CLBP, who are known to frequently experience pain symptoms are more motivated to adjust or adapt to the pain sensation, and are able to accept or cope with their situation unlike those who suffer from non-continuous pain. This assumption is based on the study of MacCracken et al. [66] which showed that psychological acceptance is associated with pain acceptance in CLBP.
Even though patients with CLBP were psychologically more affected than those with RLBP, the mean results were within the normal ranges. Earlier reports have linked CLBP with severe anxiety and depression [34, 67]. Looking at the mean HADS scores in this study, results for anxiety and depression remained below the cut off scores. Nevertheless, after looking at the range of the HADS scores, several patients with non-continuous CLBP did exhibit high levels of anxiety, whereas high levels of depression were present in some of the patients with continuous CLBP. In addition, some extreme scores were also observed for the anxiety and depression scores in some of the RLBP patients. These findings indicate that a proportion of LBP patients, despite the grade of chronicity, has a high tendency to develop these psychological issues, and that an individual assessment should always precede and form the basis for a LBP patient assessment.
Since pain catastrophizing and internal control are important factors in the development of chronic pain [68], it is expected that patients with a higher degree of chronicity would have a higher score for pain catastrophizing. However, both CLBP groups in this study did not catastrophize about pain, which is in contrast with earlier reports [69, 70]. When the range scores are observed it can be seen that some patients did have the tendency to catastrophize more about their pain, while others did not. This may be due to the limitation of the PCS instrument itself, which was used to measure pain catastrophizing in a trait-like manner. The PCS is a global, retrospective measure based on recall of self-perceived thoughts which occur during pain and it has been shown that the PCS is subject to distortion as a result of memory biases [71, 72, 73]. Finally, individual differences in pain sensitivity have important clinical implications for the development of clinical pain, and previous findings have suggested that individual differences in situational pain catastrophizing may be an important contributor to that variability [74, 75]. This could also be true for the current sample as a high variability in scores was seen.
Disability state followed the spectrum of chronicity, and was more pronounced in continuous CLBP, followed by non-continuous CLBP, and then RLBP. The low disability levels seen in patients with RLBP could be due to either less overall pain disability, or because the PDI assessed disability caused by general chronic pain, while the RMDQ assessed how physical functioning was disabled due to LBP, making the RMDQ more sensitive to the population assessed in the current study [76]. A further look into the results of the RMDQ based disability levels confirms the latter hypothesis. The higher disability rates among patients with RLBP compared to the HC have resulted from the recurrent pain experiences, which are known to alter or disturb motor control behaviour in these patients even when they are in remission [77].
Although it has been previously suggested that high levels of pain are associated with fatigue in CLBP, no evidence was present to support this assumption [78, 79]. In the current study, the non-continuous CLBP patients were most affected by fatigue. It is possible that the intermittent number of pain days-per-week experienced by patients with non-continuous CLBP may in part explain their comparatively higher fatigue severity. Patients who have frequent intermittent pain are more likely to have lower acceptance, especially when they actively attempt to control their pain. Whereas, patients with continuous CLBP who exhibit a longer and continuous symptom duration may have accepted their chronic pain condition and adjusted their lifestyle accordingly, making them less disabled by fatigue complaints.
Clinical implications
This study emphasizes that there is substantial evidence to suggest that psychological, disability and fatigue-related patient characteristics are important factors to evaluate and to take into account when setting up treatment programmes for RLBP, non-continuous and continuous CLBP patients. Not all LBP patients seem to need extensive treatment interventions focusing on all aspects. Patients with RLBP are not likely to standardly benefit from cognitive behavioural therapy as their pain-related beliefs, cognitions and attitudes are usually not distorted as is the case for CLBP. Indeed, in CLBP these psychological factors seem to contribute to the pain to a larger extent. The use of cognitive behavioural therapy has shown to be of great benefit during rehabilitation in spinal pain [80, 81, 82]. Non-continuous CLBP patients suffering from severe anxiety and fatigue might need a more in-depth focus on psychological and pain management [83, 84]. Graded aerobic exercise at low to moderate training intensities could offer potential benefits for non-continuous CLBP patients suffering from fatigue, as previous work demonstrated how such a training approach can improve fatigue levels and the functional capacity of patients with chronic disorder [83, 85, 86, 87, 88].
Continuous CLBP patients, on the other hand, are greatly affected by LBP which inhibit their daily activities. To reduce disability due to LBP, an intervention promgramme comprising graded activities and motor control training to reduce their LBP disability level might be recommended [89]. In the RLBP patients, focus should also be directed to restoring disability levels. Motor control training is known to be effective in reducing disability levels in LBP, and could therefore be recommended.
According to previous research, the efficacy of the exercise therapy in the LBP rehabilitation programme is questionable. A recent meta-analysis reported that exercise training interventions are not efficacious in CLBP [90]. Also, exercise therapy as part of a multimodal treatment only resulted in marginal improvements among (sub)acute and chronic LBP patients [12]. This emphasizes that a generalized rehabilitation programme which is not tailored based on the complete patients’ profile and thus not take psychological factors into account, may not be the best treatment strategy for those with CLBP.
Strengths and limitations
The strength of this study is that it distinguishes RLBP, non-continuous and continuous CLBP in terms of psychological, disability and fatigue-related factors. The division of the patients into the three LBP subgroups gives a better insight into how the studied factors are linked with the degree of chronicity in non-specific LBP. Clear and stringent criteria were used to define and divide the LBP subgroups, and a broad scale of valid and reliable assessments tools were used to assess the psychological, disability and fatigue-related factors.
The psychological, disability and fatigue based profiles reported in this study only offer a consequential view to the chronification of LBP. A prospective study is necessary to show causal effects of these factors and their potential contribution to the chronicity of LBP. Care should be taken by generalizing the findings to the full LBP population specifically the CLBP population. Also, there is possibility of a potential recall bias regarding some of the study outcomes. For example, the RLBP patients who were in a state of pain remission, were asked to recall their pain intensity levels over the last 6-month at the time of answering the questionnaires. Besides that, three patients with non-continuous CLBP complaints were not experiencing any pain at the time when the test was undertaken. This might indicate that the result measured on a pain day among these three patients, might deviate from the current results. This study was part of a larger study which included university visits and physical assessments, which could imply that study participation was deferred by more disabled LBP patients and possibly explain the overall low disability rates. Lastly, it could be argued that the overall sample size was small. However, the size of the sample was sufficient to show moderate to strong effects ( 0.9–0.25).
Conclusion
It has been shown that psychological factors, disability and fatigue levels are linked to the degree of chronicity among patients with LBP. Patients with RLBP showed a tendency towards a positive psychological disposition, but were slightly more disabled compared to the healthy population. Patients with non-continuous CLBP would most likely present a negative psychological mindset, become more disabled and have enhanced subjective fatigue and anxiety complaints compared to patients with RLBP. The continuous CLBP are characterized by enhanced maladaptive attitudes and believes. Within the CLBP patients, those with non-continuous symptoms showed a higher anxiety and poorer concentration when compared to those with continuous symptoms. It can therefore be concluded that a therapy approach should be determined based on the degree of chronicity and the specific patient characteristics identified during intake.
Footnotes
Acknowledgments
We would express our deepest gratitude to the participants for their support and contribution to this study.
Conflict of interest
None to report.
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