Anxiety and depression are independent predictors of quality of life of patients with chronic musculoskeletal pain

Abstract

We examined the relative impact of baseline anxiety, depression and fear of movement on health related quality of life at 12-month follow-up after a multidisciplinary pain management programme. One hundred and eleven patients who had chronic musculoskeletal pain (mean age 45 years, 65% women) attended during 2003–2005 a multidisciplinary three-phase pain management programme with a total time frame of six to seven months, totalling 19 days. The Beck Anxiety Inventory was used to rate anxiety, the Beck Depression Inventory depression, the Tampa Scale of Kinesiophobia fear of movement. The generic 15D questionnaire was used to assess health related quality of life. Baseline data were collected at admission, follow-up data at 12 months. Mean health related quality of life increased significantly from baseline to 12-month follow-up. Anxiety at baseline predicted significant negative change in the health related quality of life, depression predicted significant positive change in the health related quality of life. Fear of movement did not predict any significant change in the health related quality of life. We concluded that patients with chronic musculoskeletal pain and mild to moderate depression benefit from a multidisciplinary pain management programme in contrast to anxious patients. The findings imply further research with bigger sample sizes, other than HRQoL outcome measures as well as with other groups of patients.

Keywords

anxiety chronic pain depression pain management quality of life

Introduction

Musculoskeletal pain is a condition with a prevalence of 15% in the adult population according to a comprehensive epidemiological review (Manchikanti et al., 2009). It interferes with daily activities and is a common reason for presenting to primary care (Mallen et al., 2007). It is well recognized that several psychological and behavioural aspects relate to the chronicity process of musculoskeletal pain (Melloh et al., 2009) as well as play a significant relevance in chronic pain (Arnow et al., 2006; Linton, 2000; Sharp and Keefe, 2005). Gormsen and colleagues (2010) found that patients with fibromyalgia neuropathic pain had significantly more depression and anxiety than healthy controls both by self-rating and by a professional rating. However, the scores were low compared to other studies on mental distress in chronic pain patients, suggesting that pain subgroups differ regarding the degree of mental distress.

In a review by Pincus and colleagues (2002), psychological distress, depressive mood and somatization were implicated in the transition from acute to chronic low back pain. Greater exposure to past traumatic life events and depressed mood were strongest predictors of chronic pain (Young Casey et al., 2008). In patients with chronic neuropathic pain, strong or predominant restriction of daily activities were reported in 65%, strong or predominant sleep disturbances in 60%, feelings of depression in 34% and anxiety in 25% (Gustorff et al., 2007). The cognitive dimension of anxiety was found uniquely predictive of cognitive-affective aspects of chronic pain, including affective distress, perceived lack of control and pain severity (Vowles et al., 2004).

The relation between chronic pain and depression has been well demonstrated (Munce and Stewart, 2007; Ohayon, 2004), and they are found to show co-morbidity (Bair et al., 2003).

Pain can cause depression, even though the association can be rather complex (Bar et al., 2005; Giesecke et al., 2005; Kuusinen, 2004). A study by Lu and colleagues (2011) revealed that ambivalence over emotional expression (AEE) was positively associated with both depressive symptoms and pain: catastrophizing fully mediated the association between AEE and pain, while catastrophizing and unfulfilled needs partially mediated the association between AEE and depression.

Depression can even be an antecedent risk factor in the development of chronic pain (Lepine and Briley, 2004). This concept is supported by a recent systematic review aimed at identifying moderators and mediators for self-management programmes for patients with chronic pain. The findings reveal that depression and self-efficacy predict outcome irrespective of intervention, suggesting that these factors should be targeted at early stages in management programmes to prevent transition to chronic pain disability (Miles et al., 2011). Thus, there appears to be a strong connection between depression and chronic pain, although the underlying mechanisms still remain unclear.

Pain-related fear can be more disabling than the pain itself (Crombez et al., 1999). Fear of movement, in particular, is significantly associated with disability in patients with chronic low back pain (Schiphorst Preuper et al., 2008; Woods and Asmundson, 2008). Pain-related fear and avoidance appear to be essential features of the development of a chronic condition in patients with musculoskeletal pain (Vlaeyen and Linton, 2000).

Chronic musculoskeletal pain relates to impaired health related quality of life (HRQoL), disability indices and health risk behaviours (Strine et al., 2005). Patients with chronic pain report lower scores on several factors related to quality of life compared to controls and other patient groups (Dysvik et al., 2004). A study by Frühwald and colleagues (2001) revealed that quality of life was markedly lowered in patients with chronic low back pain, and it was rated worst by patients with most severe depression. In a study comprising of over 1000 participants, patients with back pain and patients with multiple pain localizations reported the lowest quality of life, pain catastrophizing showing the strongest association with decreased quality of life, even stronger than pain intensity (Lamé et al., 2005).

Research shows that intensive multidisciplinary bio-psycho-social rehabilitation with a functional restoration approach reduces pain and improves function by targeting physiological, psychological and behavioural factors (Guzman et al., 2002). Quality of life has been found to improve more in patients with chronic low back pain participating in a multidisciplinary rehabilitation programme compared to corresponding patients treated by usual care (Lang et al., 2003). In a more recent review made by Scascighini and colleagues (2008), strong evidence of effectiveness was detected in favour of multidisciplinary treatments in contrast to no treatment or standard medical treatment. In recent studies, multidisciplinary pain management programmes have shown long-term effectiveness in targeting multiple domains affected by the pain condition (Oslund et al., 2009), as well as in increasing possibilities to return to work (Norlund et al., 2009).

A recent study has revealed that age and depression predict favourable outcomes for rehabilitation of patients with chronic pain. Bremander and colleagues (2011) stated that multidisciplinary pain rehabilitation, using a non-pharmacological cognitive approach, yielded a better outcome concerning HRQoL measures in younger participants with higher baseline depression scores.

The aim of the study

The literature reveals that various psychological distress factors, especially anxiety and depression, relate to chronic pain as well as impaired quality of life. Furthermore, psychological distress and impaired quality of life seem to be interrelated in the conditions of patients with chronic pain. Multidisciplinary pain management programmes seem effective in reducing psychological distress as well as increasing quality of life among patients with chronic pain. However, no study exploring the relative impact of anxiety, depression and fear of movement in predicting HRQoL in a single multivariate model seems available at present. The aim of this prospective study was to examine the impact of baseline levels of anxiety, depression and fear of movement on the HRQoL at 12-month follow-up among patients with chronic musculoskeletal pain after participating in a multidisciplinary pain management programme.

Materials and methods

Participants

The study sample comprised of 111 patients with chronic musculoskeletal pain, all meeting the criteria of the International Association for the Study of Pain (IASP, 2003) for chronic pain. After being examined and getting medical treatment in basic and special healthcare settings, the patients were referred to a multidisciplinary pain management programme during 2003–2005. When attending the pain management programme exclusion criteria were diagnosed primary fibromyalgia and diagnosed current major psychiatric disorders, which have been considered to be contraindications for this type of somatic rehabilitation. Thus, patients with current major depressive disorder (MDD) were excluded from the study. Even an MDD diagnosis made by a consultant psychiatrist during the rehabilitation course resulted in an exclusion from the study. However, a history of MDD was not an exclusion criterion. The patients’ demographic and baseline clinical data are shown in Table 1.

Table 1.

Patients’ demographics and clinical data at baseline

	N=111
Demographics
Number of females, %	72 (65)
Age, years, mean (SD)	45 (8)
Marriage or common law marriage, n (%)	81 (73)
Education
Primary school	25 (23)
Secondary school	20 (18)
College	15 (14)
Graduate	51 (46)
Clinical
Duration of pain, n (%)
≤1, years	5 (5)
1–5, years	76 (68)
> 5, years	30 (27)
IASP, n (%)
Lower extremities	7 (6)
Neck	25 (23)
Head	6 (5)
Chest	2 (2)
Back	58 (52)
Upper extremities	7 (6)
Other	6 (5)
Beck Anxiety Inventory, mean (SD)	12 (7)
Beck Depression Inventory, mean (SD)	14 (8)
Tampa Scale of Kinesiophobia (SD)	40 (9)

Intervention

The purpose of the pain management programme was to regain overall functioning. The group rehabilitation design comprised of physical and functional exercises, evaluation of the social situation, psychological assessment of pain-related stress factors and personal pain management training, including mindfulness and relaxation practising. The programme was conducted by a multidisciplinary rehabilitation team, including a physician, psychologist, social worker, two physiotherapists and an occupational therapist, according to IASP (2009) recommendations for pain treatment services. The rehabilitation team had been provided training in a bio-psycho-social frame of reference and had a cognitive-behavioural working approach. The team offered an activating approach, encouraging the patients towards individual exercise in order to regain function and improve self-management of the pain. The pain management group size varied between eight and 10 patients, the programme comprised of three phases over a time frame of six to seven months, totalling 19 (3+13+3) days.

During the initial three-day rehabilitation phase, patients encountered each of the team members for basic evaluations, and received individual physical exercise and training schedules from the physiotherapist. Individual training goals were defined. During the 13-day rehabilitation phase, the patients had interventions with the physician, psychologist and occupational therapist twice and physiotherapists six times, all for approximately 60 minutes. The exercise and training programmes were re-assessed and adjusted according to the physical conditions of the patients at that time. Physical exercise included water gymnastics, gym exercises, balance, relaxation and flexibility training, Pilates-type exercises and outdoor walking. The final three-day rehabilitation stage comprised of, beside individual physical and functional exercises, personally focused summary discussion and future goal setting with the team members. Again, the exercise and training programmes were, when necessary, re-assessed and adjusted according to the physical conditions of the patients.

The financier, the Social Insurance Institution of Finland, required that the programme contain scheduled activities of 35 hours per week. In addition to individual appointments lectures and discussion groups were held by the team members. Educational lectures included basic information about pain mechanisms, chronic pain and adaptation to pain conditions. The topics in the discussion groups focused on pain related psychological distress as well as ways to reduce the stress, in order to process pain related affects and experiences with peers.

Measurements

The study included 141 participants from which adequate data were available for 111 participants, giving a response rate of 79%. All questionnaires used in the study were completed at baseline, before any interventions, and at 12-month follow-up, the latter collected by posted questionnaires. Anxiety symptoms were measured using the Beck Anxiety Inventory (BAI) (Beck and Steer, 1993). The BAI score was dichotomized at the median (> 10) for regression analysis purposes. Depressive symptoms were measured with the Beck Depression Inventory (BDI), version II (Beck et al., 1996, 2004). The BDI score was dichotomized at the clinical reference threshold for mild depression (> 13). The Finnish version of the Tampa Scale of Kinesiophobia (TSK-FV) was used to assess fear of movement (Kori et al., 1990). The TSK-FV was dichotomized at median (> 38).

The Health State Descriptive System (15D) was used as the outcome measure for HRQoL. The 15D is a generic, 15-dimensional, standardized, self-administered questionnaire (Sintonen, 1994a, 2001) including dimensions of mobility, vision, hearing, respiration, sleeping, eating, speaking, elimination, usual activities, mental function, discomfort and symptoms, depression, distress, vitality and sexual activity. The severity of each dimension is measured on a five-grade scale (1–5). The 15D can be used both to obtain a profile across the 15 dimensions and a single index score ranging from 0 (being dead) to 1 (full health). The 15D has proven good reliability and validity as an instrument for measuring HRQoL (Hawthorne et al., 2001; Sintonen, 1994a, 1995), as well as in describing the impact of various chronic conditions, for example musculoskeletal disorders, on HRQoL (Saarni et al., 2006).

Statistics

The results are expressed as means with standard deviation (SD) and 95% confidence intervals (CI). Statistical comparison of changes in outcome measures was performed using a permutation test with Monte Carlo p-value. Multivariate logistic regression model was used to estimate odds ratios (OR) and their 95% intervals (95% CI) when predicting 15D change. The minimum clinically important change of 15D score is ≥ 0.03 on the 0–1 scale, according to the literature (Sintonen, 1994b).

Ethics

The study obtained research permission from the scientific board at the ORTON Foundation. The participants signed an informed consent prior to their inclusion in the study.

Results

For the whole study group the HRQoL mean increased significantly from 0.768 (0.085) by 0.018 (95% CI: 0.000 to 0.036) (p = .049) at the 12-month follow-up.

The baseline score of anxiety was 12.2 (6.9), of depression 14.3 (7.9) and of fear of movement 39.6 (9.0), respectively. The anxiety score at 12 months changed by −0.5 (95% CI: –0.9 to 1.9) (NS). Significant change at 12 months was found for the depression score, with a change of −2.1 (95% CI: 0.6 to −3.7) (p = .007) and fear of movement, with a change of −1.8 (95% CI: 0.4 to −3.1) (p = .012).

Symptoms of anxiety and depression were independent predictors of HRQoL change (15D ≥ 0.03) at the 12-month follow-up: for anxiety at baseline (BAI > 10) OR was 0.19 (95% CI: 0.07 to 0.53), for depression (BDI > 13) OR = 2.72 (95% CI: 0.97 to 7.66), respectively. Baseline score of fear of movement did not significantly predict HRQoL change at 12-month follow-up. Results are shown in Fig. 1.

Among depressed (BDI > 13) patients the mean HRQoL at baseline 0.768 (0.061) increased by 0.059 (95% CI: 0.019 to 0.100) at month 12 (p = .0069). The results are shown in Fig. 2.

Discussion

The strength of this study is the finding that symptoms of anxiety and depression predicted HRQoL independently: anxiety at baseline predicted significant decrease of the HRQoL whereas depression predicted a significant increase of the HRQoL. This finding, which differs from previously published results regarding the impact of depression, requires reflection on background factors as well as on differences in anxiety and depression.

The findings might be explained by temporal aspects of psychological factors related to the pain condition. Anxiety could indicate an earlier phase of the psychological adaptation process to the chronic pain syndrome, possibly corresponding to affective reactions in the beginning of crisis processes (Epperson, 1977). Depression might rather indicate some degree of mental processing of the bereavement experiences (Kendler et al., 2008), possibly reflecting affect more typical at a later state of the crisis process (Epperson, 1977). The benefit from rehabilitation interventions could thus be time-dependent reflecting the degree of psychological adaptation to the pain condition.

The findings might also be explained by the different characteristics of the anxiety and depression states. The tripartite model of emotion (Clark and Watson, 1991) defines a general factor, ‘negative affect’, which represents a shared influence on anxiety and depression, and further specifies two specific factors, ‘physiological hyper-arousal’, in anxiety, and ‘low positive affect’, in depressive states (Clark and Watson, 1991). Anxiety and depression might hence influence the patients’ responsiveness to rehabilitation interventions differently and thus alter the possibility to re-evaluate their situation cognitively.

A complementary interpretation of the findings could be made by considering the state of physiological hyper-activation common in anxiety. One applicable model is the ‘window of tolerance’ derived from trauma-psychotherapies. According to the model, therapeutic processing of traumatically stressful experiences implies an optimal physiological arousal in order to enable therapeutic changes (Ogden et al., 2006; Siegel, 1999). When the physiological arousal is within tolerable levels, it makes the processing of cognitive, emotional and sensory-motor aspects possible. Anxious pain patients are frequently in a hyperactive state, that is, heightened psychological and physiological tension, marked by effects like reduced pain tolerance, anxiety, exaggeration of startle responses, insomnia, fatigue and accentuation of personality traits, which might disable them from benefitting from the rehabilitation interventions. Patients with depression, in turn, could achieve a higher, more optimal activation level, enabling them to process their situation and internalize aspects of the rehabilitation more efficiently. This viewpoint gets support from the review study of Stammes and Spijker (2009), in which it is stated that physical training can be effective for treating patients with mild or moderate depression.

Depression medication provides an alternative explanation for the rehabilitation benefits found in depressed patients only in this study. Occasionally clinical depression, implying medical treatment, is diagnosed during the rehabilitation process. The anti-depressives could improve the overall functioning. Bair and colleagues (2003) found that depression medication yielded primarily pain related relief, while the reduction of depression was secondary. Moreover, the literature shows that especially ‘dual-action’ antidepressants show an independent analgesic effect (Sindrup et al., 2003). Anti-depressive medication therefore can contribute to the decrease of both pain intensity and depression. Indeed the weakness of this explanation is that anti-depressives are frequently used in anxiety states (Schosser and Kasper, 2009). Thus, it could be assumed that anti-depressive medication would not only have a therapeutic effect on depression but on anxiety as well. However, the role of anti-depressive medication was not controlled in this study.

There are limitations in this study. The appropriate reference level for clinically relevant 15D change seems challenging. Sintonen, the developer of the 15D, has stated that a change of 0.03 is clinically relevant for people (Sintonen, 1994b) in the sense that they feel the difference, and this level has been applied in HRQoL studies (Hirvonen et al., 2006). However, further research is needed to determine criteria for a change of 15D more specifically. No study specifically clarifying this issue seems available at present. The sample size of 111 in the study was too small and so caution should be taken in drawing further conclusions from the findings.

In conclusion, chronic musculoskeletal pain patients with minor to moderate depression states seem to benefit from a multidisciplinary pain management programme in contrast to anxious patients. Theoretically, derived from the viewpoints above, patients with depression could benefit from activating interventions, patients with anxiety from arousal-lowering relaxation techniques. Minor or moderate depression should not be a contra-indication for multidisciplinary pain management programmes of this type. The findings need replication with larger sample sizes, using alternative outcome measures and other patients groups. In further studies, both pain medication and psychotropic medication should be controlled for, especially the dual-action antidepressants (Sindrup et al., 2003).

Footnotes

Competing Interests

None declared.

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